AP 155 EDFS for sale


Aug 10, 2001

 


----------------------------

#3216 Aug 10, 2001

Hi All,



Saw an add in Astromart for an AP 155 EDFS that claims to be less than one

year old, delivered in 2000. How can this be, since 155 production is just

about to begin and, to my knowledge, there has not been any 155's made

since summer of 1998. Did I miss a production run somewhere a long the

line? Where there NEW 155's delivered in 2000?



Andy



----------------------------

#3221 Aug 10, 2001

155 orders taken in 1999 were delivered in 2000.

Marj



--- In ap-gto@y..., "Andy Forsberg" CS-Imaging@p...> wrote:

> Hi All,

>

> Saw an add in Astromart for an AP 155 EDFS that claims to be less

than one

> year old, delivered in 2000. How can this be, since 155 production

is just

> about to begin and, to my knowledge, there has not been any 155's

made

> since summer of 1998. Did I miss a production run somewhere a long

the

> line? Where there NEW 155's delivered in 2000?

>

> Andy



----------------------------

#42526 Dec 12, 2013

Well, it all depends. If you are ever thinking of getting into breezy conditions or variable light winds or small gusts, the AP900 is the mount for you. While the Mach1GTO seems to be compact and overall a "lighter package, it really isn't. For the same astro load, you will need a counterweight shaft with the same mass of counterweights. You will also require a pier or tripod which will work out fairly close in size and weight no matter which way you go. The Mach1GTO wieghs in at 30+ pounds. The 900 is 40+ but easily disassembles into two small parts, each of which is lighter and generally smaller than the Mach1GTO. So, you do the math. The 900 will have one more piece than the equivalent Mach1 and will only weigh slightly more. If you decide to keep the 900, get the Dec upgrade.As to cons, the 900 will require an 8" pier whereas the Mach1GTO only needs a 6" pier / tripod. This means the tripod is somewhat larger and heavier and more difficult/expensive to acquire. I don't know if anyone has tried to get a dedicated adapter machined for the 6" Eagle pier for the 900 or an adapter which could couple to the 900FSA, but it might be worth looking into. The Mach1GTO can be fitted into a single medium sized Pelican case but it is fairly heavy and a separate counterweight box is still required.





---In ap-gto@yahoogroups.com, rchozick@...> wrote:

I just bought a 1997 AP 155 f/7 EDFS and a 2001 AP 900 mount as a set. I have a Mach1 already and I would really like to keep the Mach1 and sell the 900. I have been told that the Mach1 can handle the 155 photographically if I use a light weight setup like the Baader finder/guidesocpe, which I ordered. I don't have a heavy setup as I use an SBIG STF-8300 with 8 filter wheel and no other accessories like a rotator or off axis guider. Could I do this setup for imaging on the Mach 1 or would most recommend the 900 or greater due to the long moment arm of this setup? I would love to hear from Mach 1 users with this telescope.



I would also like to hear about the differences the DEC upgrade makes to the older 900s. If I keep the 900 I need to know if I should have the mod made.



I put the 155 on my Mach1 last night for its first light visually. I was amazed that in medium seeing with a lot moisture in the air and 28 degrees I could see Jupiter in a way I have never seen. With a 5mm Nagler I saw beautiful detail and the brownish color that I have not seen since I was younger. In not so good conditions I clearly saw the E star in the Triangulum. The Moon showed detail I could never have imagined. Sigma Orionis was sharp as could be with the faint star really obvious. I have seen these objects many times in my 12.5 inch Dob but it is unbelievable that they look like this in a 6 inch scope. This is one incredible scope that I cannot wait to see my images.



i would appreciate help with the decision for the proper mount.



Robert Chozick

rchozick@...

www.pbase.com/rchozick



----------------------------

#42527 Dec 12, 2013

Just a comment about pier size. I had a 4" pier when I got my AP900. Although I'd get something bigger if I didn't already have the 4", I've continued to use it and have never noticed a problem (using either an FSQ-106 or a Planewave 12.5). I think concerns about needing a big pier are a bit overblown. . ��Greg .. ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of JunkMailGoesHere@...Sent: Thursday, December 12, 2013 10:37 AMTo: ap-gto@yahoogroups.comSubject: [ap-gto] RE: AP 155 EDFS first light and Mach1 vs 900



----------------------------

#42528 Dec 12, 2013

I think a 4" fixed (solid cement or thickwall steel) pier might be ok with an AP900 but it is close to the limit with short focal length, and definitely pushing the envelope with something like the Planewave 12.5. My personal preference would be a fixed 6" pier. For portable use, a 6" tripod like the Eagle would be a minimum for the AP900 and personally I would go with an 8" ATS or the AP portable pier. I'd also suggest a Rob Miller TRI36M but unfortunately it seems he has disappeared for close to a year now, and with time passing, is less and less likely to re-appear.



----------------------------

#42529 Dec 12, 2013

At least in my case the 4" (it is thick wall steel with a concrete base from La Sueur -. I actually have 2 for separate locations) works well with the Planewave 12.5. If I didn't already have the 4" I'd go with a good 8" pier. It's not that much more money given how much a good mount, scope and camera cost. But, based on my limited experience, I'd say conventional wisdom about pier size is overly cautious. .. ��Greg ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of JunkMailGoesHere@...Sent: Thursday, December 12, 2013 12:40 PMTo: ap-gto@yahoogroups.comSubject: RE: [ap-gto] RE: AP 155 EDFS first light and Mach1 vs 900







----------------------------

#42532 Dec 12, 2013

The 900 is 40+ but easily disassembles into two small parts, each

> of which is lighter and generally smaller than the Mach1GTO.



If I knew four years ago that by now I'd have an observatory under a reasonably dark sky, then I would have bought the 900 instead of the Mach1. However -- the Mach1 also splits into two major subassemblies (DEC and RA), which I think is the same as the 900. I'm not sure that this parameter, by itself, should be critical in deciding between the two.



----------------------------

#42533 Dec 12, 2013

Why not sell both Mach1 and AP900 and get AP1100. AP1100 has one of my favorite features that AP900 does not have and it's through the mount cabling (Mach1 also has this). Keep all necessary accessories like counterweights, saddle and tripod/pier from AP900/Mach1 for AP1100. AP1100 as a whole is not that heavy and a few pounds lighter than AP900. If you can easily carry AP900, then the cables can remain through the mount of AP1100 and you can carry the whole thing.



Peter

--- In ap-gto@yahoogroups.com, Robert Chozick rchozick@...> wrote:

>

> I just bought a 1997 AP 155 f/7 EDFS and a 2001 AP 900 mount as a set. I have a Mach1 already and I would really like to keep the Mach1 and sell the 900. I have been told that the Mach1 can handle the 155 photographically if I use a light weight setup like the Baader finder/guidesocpe, which I ordered. I don't have a heavy setup as I use an SBIG STF-8300 with 8 filter wheel and no other accessories like a rotator or off axis guider. Could I do this setup for imaging on the Mach 1 or would most recommend the 900 or greater due to the long moment arm of this setup? I would love to hear from Mach 1 users with this telescope.

>

> I would also like to hear about the differences the DEC upgrade makes to the older 900s. If I keep the 900 I need to know if I should have the mod made.

>

> I put the 155 on my Mach1 last night for its first light visually. I was amazed that in medium seeing with a lot moisture in the air and 28 degrees I could see Jupiter in a way I have never seen. With a 5mm Nagler I saw beautiful detail and the brownish color that I have not seen since I was younger. In not so good conditions I clearly saw the E star in the Triangulum. The Moon showed detail I could never have imagined. Sigma Orionis was sharp as could be with the faint star really obvious. I have seen these objects many times in my 12.5 inch Dob but it is unbelievable that they look like this in a 6 inch scope. This is one incredible scope that I cannot wait to see my images.

>

> i would appreciate help with the decision for the proper mount.

>

> Robert Chozick

> rchozick@...

> www.pbase.com/rchozick

>



----------------------------

#42534 Dec 12, 2013

Hi Peter. ��I miss the SX forum but don't have an SX camera anymore, except for the Lodestar and that just guides. ��Thanks for all the replies on this, although the discussion kind of morphed into a pier discussion. ��I knew I should probably have a 900 or greater. ��I just wanted to see if the Mach 1 would be ok. ��I don't want to sell both and buy an 1100 because the only reason I have the 900 is that it came in a package with the 155 and I need to sell one of these mounts. ��A local astronomy store was selling them together on consignment. ��I think I will keep the 900 and sell the Mach1. ��I will eventually sell the 900 for a newer 900 or an 1100 but I have to first recover from the financial shock of getting the 155 EDFS. ��I don't use the through the mount cabling because I never keep the setup cabled permanently. ��I would like to get an 1100 eventually.

Robert

On Dec 12, 2013, at 7:37 PM, topboxman2000 pnagy@...> wrote:

��



Why not sell both Mach1 and AP900 and get AP1100. AP1100 has one of my favorite features that AP900 does not have and it's through the mount cabling (Mach1 also has this). Keep all necessary accessories like counterweights, saddle and tripod/pier from AP900/Mach1 for AP1100. AP1100 as a whole is not that heavy and a few pounds lighter than AP900. If you can easily carry AP900, then the cables can remain through the mount of AP1100 and you can carry the whole thing.



Peter



--- In ap-gto@yahoogroups.com, Robert Chozick rchozick@...> wrote:

>

> I just bought a 1997 AP 155 f/7 EDFS and a 2001 AP 900 mount as a set. I have a Mach1 already and I would really like to keep the Mach1 and sell the 900. I have been told that the Mach1 can handle the 155 photographically if I use a light weight setup like the Baader finder/guidesocpe, which I ordered. I don't have a heavy setup as I use an SBIG STF-8300 with 8 filter wheel and no other accessories like a rotator or off axis guider. Could I do this setup for imaging on the Mach 1 or would most recommend the 900 or greater due to the long moment arm of this setup? I would love to hear from Mach 1 users with this telescope.

>

> I would also like to hear about the differences the DEC upgrade makes to the older 900s. If I keep the 900 I need to know if I should have the mod made.

>

> I put the 155 on my Mach1 last night for its first light visually. I was amazed that in medium seeing with a lot moisture in the air and 28 degrees I could see Jupiter in a way I have never seen. With a 5mm Nagler I saw beautiful detail and the brownish color that I have not seen since I was younger. In not so good conditions I clearly saw the E star in the Triangulum. The Moon showed detail I could never have imagined. Sigma Orionis was sharp as could be with the faint star really obvious. I have seen these objects many times in my 12.5 inch Dob but it is unbelievable that they look like this in a 6 inch scope. This is one incredible scope that I cannot wait to see my images.

>

> i would appreciate help with the decision for the proper mount.

>

> Robert Chozick

> rchozick@...

> www.pbase.com/rchozick

>







----------------------------

#42537 Dec 12, 2013

I got the mount and scope as a unit but only wanted to spend money on the scope itself so one of the mounts has to go so my purchase price for the scope is not so high. ��The seller would not split up the scope and mount. ��There's no profit in this transaction; quite the opposite. ��I will keep the 900 for now and upgrade as soon as I can.

Robert

On Dec 12, 2013, at 11:44 PM, topboxman2000 pnagy@...> wrote:

��



Hi Robert,



That was kind of the point I was trying to say. If you sell both Mach1 and AP900 and get AP1100, you might end up some profit and take advantage of through the mount cabling. My setup is always portable and through the mount cabling is extremely beneficial for portable setup. You never have to worry about cables getting caught during imaging while you are sleeping.



Peter



--- In ap-gto@yahoogroups.com, Robert Chozick rchozick@...> wrote:

>

> Hi Peter. I miss the SX forum but don't have an SX camera anymore, except for the Lodestar and that just guides. Thanks for all the replies on this, although the discussion kind of morphed into a pier discussion. I knew I should probably have a 900 or greater. I just wanted to see if the Mach 1 would be ok. I don't want to sell both and buy an 1100 because the only reason I have the 900 is that it came in a package with the 155 and I need to sell one of these mounts. A local astronomy store was selling them together on consignment. I think I will keep the 900 and sell the Mach1. I will eventually sell the 900 for a newer 900 or an 1100 but I have to first recover from the financial shock of getting the 155 EDFS. I don't use the through the mount cabling because I never keep the setup cabled permanently. I would like to get an 1100 eventually.

>

> Robert

>

> On Dec 12, 2013, at 7:37 PM, topboxman2000 pnagy@...> wrote:

>

>

>

> Why not sell both Mach1 and AP900 and get AP1100. AP1100 has one of my favorite features that AP900 does not have and it's through the mount cabling (Mach1 also has this). Keep all necessary accessories like counterweights, saddle and tripod/pier from AP900/Mach1 for AP1100. AP1100 as a whole is not that heavy and a few pounds lighter than AP900. If you can easily carry AP900, then the cables can remain through the mount of AP1100 and you can carry the whole thing.

>

> Peter

>

> --- In ap-gto@yahoogroups.com, Robert Chozick rchozick@> wrote:

> >

> > I just bought a 1997 AP 155 f/7 EDFS and a 2001 AP 900 mount as a set. I have a Mach1 already and I would really like to keep the Mach1 and sell the 900. I have been told that the Mach1 can handle the 155 photographically if I use a light weight setup like the Baader finder/guidesocpe, which I ordered. I don't have a heavy setup as I use an SBIG STF-8300 with 8 filter wheel and no other accessories like a rotator or off axis guider. Could I do this setup for imaging on the Mach 1 or would most recommend the 900 or greater due to the long moment arm of this setup? I would love to hear from Mach 1 users with this telescope.

> >

> > I would also like to hear about the differences the DEC upgrade makes to the older 900s. If I keep the 900 I need to know if I should have the mod made.

> >

> > I put the 155 on my Mach1 last night for its first light visually. I was amazed that in medium seeing with a lot moisture in the air and 28 degrees I could see Jupiter in a way I have never seen. With a 5mm Nagler I saw beautiful detail and the brownish color that I have not seen since I was younger. In not so good conditions I clearly saw the E star in the Triangulum. The Moon showed detail I could never have imagined. Sigma Orionis was sharp as could be with the faint star really obvious. I have seen these objects many times in my 12.5 inch Dob but it is unbelievable that they look like this in a 6 inch scope. This is one incredible scope that I cannot wait to see my images.

> >

> > i would appreciate help with the decision for the proper mount.

> >

> > Robert Chozick

> > rchozick@

> > www.pbase.com/rchozick

> >

>

>

>

> Robert Chozick

> rchozick@...

>



----------------------------

#42538 Dec 13, 2013

When I was using my Mach1 for star parties, I kept the cables running through the mount but coiled up.

> I don't use the through the mount cabling because I never keep the > setup cabled permanently. I would like to get an 1100 eventually.

>

> Robert



----------------------------

#42543 Dec 13, 2013

I've never taken my Mach1 apart. As you say, at 30 lbs, why bother? But if it's important to you, it CAN be taken apart. A friend of mine breaks apart his Mach1 for storage in a case.

--- In ap-gto@yahoogroups.com, JunkMailGoesHere@...> wrote:

>

> Splitting the Mach1GTO requires Allen keys to remove and replace bolts. At 30 pounds, why bother? The AP900 is 100% built for tool-less assembly/disassembly and use. I guess this does bring up my one criticism of the new AP1100. For portable assembly/disassembly, it requires tools and playing with fiddly little parts like bolts in the dark to:

> 1) open and close the cable access port cover

>

> 2) attach the mount to the pier or FSA or whatever

>

> 3) to remove the secondary bolts from the Dec and top plate

>

> 4) attach the CP3

>



----------------------------

#42661 Dec 21, 2013

I just got a used 1997 AP 155 EDFS and was looking at the full Moon and saw a thin green tinge around the limb of the full Moon. The detail was fantastic but I am just wondering if that is ok or if the green shows that the objective is out of collimation. I know the full Moon is something brighter than I will ever image but just wanted to make sure. I was using a 20mm Nagler Type 5 and 13mm Type 6. What is interesting is I have a Kokusai Kohki 30mm Widescan and it showed a slight purple color around the limb. I don't have a simple orthoscopic or plossl eyepiece to test it with more simple optics. Is this normal? I though high end APOs never showed color.



Robert Chozick

rchozick@...







----------------------------

#42690 Dec 22, 2013

Robert, I started my adventures in astro-photography with a GM-8 and liked it very much.�� I had 20 to 25 pounds of gear on it, which was clearly too much for photography, but when I used it visually (not often) it performed very well.�� The 155EDFS is about that weight, but longer than the scopes I used.�� So I think it would do OK, but might struggle with wind.

Greg





From: Robert Chozickrchozick@...> To: ap-gto@yahoogroups.com Sent: Sunday, December 22, 2013 6:31 PM Subject: [ap-gto] GM8 and 155 EDFS

��Is a GM8 strong enough to use a 155 EDFS visually? I would image on a 900 but wanted something to use when I wasn't using the 155 for imaging.



Robert



Sent from my iPhone



----------------------------

#42691 Dec 23, 2013

Thanks Greg.

Robert

On Dec 22, 2013, at 10:36 PM, Greg Marshall phototwist@...> wrote:

��

Robert, I started my adventures in astro-photography with a GM-8 and liked it very much.�� I had 20 to 25 pounds of gear on it, which was clearly too much for photography, but when I used it visually (not often) it performed very well.�� The 155EDFS is about that weight, but longer than the scopes I used.�� So I think it would do OK, but might struggle with wind.

Greg





From: Robert Chozickrchozick@...> To: ap-gto@yahoogroups.com Sent: Sunday, December 22, 2013 6:31 PM Subject: [ap-gto] GM8 and 155 EDFS

��Is a GM8 strong enough to use a 155 EDFS visually? I would image on a 900 but wanted something to use when I wasn't using the 155 for imaging.



Robert



Sent from my iPhone



----------------------------

#42693 Dec 23, 2013

Thanks John. ��I used Universal Astronomic mounts in the past and still have one. �� I think I want an equatorial but I will consider an alt/az. ��Thanks for reminding me. ��I used to be solely an alt/az guy until I decided to try astrophotography.

Robert

On Dec 23, 2013, at 9:42 AM, John Gaul johngaul@...> wrote:

��

Robert,

As an alternative to the GM8, for visual use, you might consider an alt az mount such as a "Half Hitch Telescopes" mount. The planned model "FTX" could meet your needs. Given it doesn't exist yet, and the timescale for delivery is uncertain, you would need to be prepared to wait, perhaps 6 months. I'm sure it will be great though if you can wait. Alternatively, you might find a used Nova Hitch on AstroMart.

John

On 23 Dec 2013, at 14:46, Robert Chozick rchozick@...> wrote:

��Thanks Greg.

Robert

On Dec 22, 2013, at 10:36 PM, Greg Marshall phototwist@...> wrote:

��

Robert, I started my adventures in astro-photography with a GM-8 and liked it very much.�� I had 20 to 25 pounds of gear on it, which was clearly too much for photography, but when I used it visually (not often) it performed very well.�� The 155EDFS is about that weight, but longer than the scopes I used.�� So I think it would do OK, but might struggle with wind.

Greg





From: Robert Chozickrchozick@...> To: ap-gto@yahoogroups.com Sent: Sunday, December 22, 2013 6:31 PM Subject: [ap-gto] GM8 and 155 EDFS

��Is a GM8 strong enough to use a 155 EDFS visually? I would image on a 900 but wanted something to use when I wasn't using the 155 for imaging.



Robert



Sent from my iPhone



----------------------------

#42694 Dec 23, 2013

I use my 155 EDF, a tad heavier with 4"focuser'on a CGE for visual and portability.�� Works well.

I just placed a photo in the Eddwen folder so you might judge relative size.�� I'm not familiar with the GM-8, but this might help.

Best,

Edd WeningerOvergaard AZ



----------------------------

#42695 Dec 23, 2013

Thanks. ��I know a CGE would work but it is too heavy for me to lift. �� I had to sell mine because of that.

Robert

On Dec 23, 2013, at 10:54 AM, Eddwen@... wrote:

��

I use my 155 EDF, a tad heavier with 4"focuser'on a CGE for visual and portability.�� Works well.

I just placed a photo in the Eddwen folder so you might judge relative size.�� I'm not familiar with the GM-8, but this might help.

Best,

Edd WeningerOvergaard AZ



----------------------------

#42700 Dec 24, 2013

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?



www.pbase.com/rchozick/image/153901637



Robert Chozick

rchozick@...



----------------------------

#42701 Dec 24, 2013

A large reflection on the bottom of the image?? Can you point to it because your image shows nothing there.��As far as reflections, field flatteners are not normally the source of strange reflections. One thing people forget is that a curved surface, such as those on the edge of a camera adapter or even the edge of a filter, make for nice reflective mirrors that can take stray light from a bright star near the edge or even past the edge of the field and produce a nice semi-circular arc in the field. It is generally an anodized surface that causes this. Even though it is black anodize, it nevertheless can be highly reflective. Whenever you are looking for stray reflections, remove the camera and look up at those mating surfaces near the focal plane, because that is where you will discover most of your problems.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 12:41 pm

Subject: [ap-gto] First light for 155 EDFS - Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





---------------

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----------------------------

#42702 Dec 24, 2013

Thanks Roland. ��The reflection is faint and looks like a ring to the right of the Flame. ��I have a 15mm Baader t thread extension between the field flattener and the camera that may be the culprit. ��It is quite possible the reflection of Alnitak on this adapter did this. ��I modified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@... wrote:

��

A large reflection on the bottom of the image?? Can you point to it because your image shows nothing there.��As far as reflections, field flatteners are not normally the source of strange reflections. One thing people forget is that a curved surface, such as those on the edge of a camera adapter or even the edge of a filter, make for nice reflective mirrors that can take stray light from a bright star near the edge or even past the edge of the field and produce a nice semi-circular arc in the field. It is generally an anodized surface that causes this. Even though it is black anodize, it nevertheless can be highly reflective. Whenever you are looking for stray reflections, remove the camera and look up at those mating surfaces near the focal plane, because that is where you will discover most of your problems.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 12:41 pm

Subject: [ap-gto] First light for 155 EDFS - Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





---------------

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----------------------------

#42704 Dec 24, 2013

My monitor's gamma must be different. ��I will check out the t thread extension.

Robert

On Dec 24, 2013, at 1:54 PM, chris1011@... wrote:

��

I still don't see it. Anyone else see it?��Roland

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 1:30 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





Thanks Roland. ��The reflection is faint and looks like a ring to the right of the Flame. ��I have a 15mm Baader t thread extension between the field flattener and the camera that may be the culprit. ��It is quite possible the reflection of Alnitak on this adapter did this. ��I modified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@... wrote:



��

A large reflection on the bottom of the image?? Can you point to it because your image shows nothing there.

��As far as reflections, field flatteners are not normally the source of strange reflections. One thing people forget is that a curved surface, such as those on the edge of a camera adapter or even the edge of a filter, make for nice reflective mirrors that can take stray light from a bright star near the edge or even past the edge of the field and produce a nice semi-circular arc in the field. It is generally an anodized surface that causes this. Even though it is black anodize, it nevertheless can be highly reflective. Whenever you are looking for stray reflections, remove the camera and look up at those mating surfaces near the focal plane, because that is where you will discover most of your problems.��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 12:41 pmSubject: [ap-gto] First light for 155 EDFS - Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





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----------------------------

#42705 Dec 24, 2013

It may be the ring he sees centeredbetween the Horsehead and the Flame. It���s faint and large at this extremestretch. The bright star is almost to the right side of the ring. Now seeingthis in the extreme stretch you can barley see it on the first posted image. It���at the bottom of the image. ��Steve �� �� ��

From:ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com ] On Behalf Of chris1011@...

Sent: Tuesday, December 24, 20132:54 PM

To: ap-gto@yahoogroups.com

Subject: Re: [ap-gto] First lightfor 155 EDFS - Horsehead

���� I still don't see it. Anyone else see it?

��

Roland

-----OriginalMessage-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com >

Sent: Tue, Dec 24, 2013 1:30 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��The reflection is faint and looks like a ring to the rightof the Flame. ��I have a 15mm Baader t thread extension between the fieldflattener and the camera that may be the culprit. ��It is quite possiblethe reflection of Alnitak on this adapter did this. ��I modified the imageto show the reflection better: ��

www.pbase.com/rchozick/image/153902305

��

Robert

��On Dec 24, 2013, at 12:49 PM, chris1011@... wrote:

���� ��

A largereflection on the bottom of the image?? Can you point to it because your imageshows nothing there.

��

As faras reflections, field flatteners are not normally the source of strangereflections. One thing people forget is that a curved surface, such as those onthe edge of a camera adapter or even the edge of a filter, make for nicereflective mirrors that can take stray light from a bright star near the edgeor even past the edge of the field and produce a nice semi-circular arc in thefield. It is generally an anodized surface that causes this. Even though it isblack anodize, it nevertheless can be highly reflective. Whenever you arelooking for stray reflections, remove the camera and look up at those matingsurfaces near the focal plane, because that is where you will discover most ofyour problems.

��

Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 12:41 pm

Subject: [ap-gto] First light for 155 EDFS - HorseheadI took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night.�� I could only get 5 - 30min Ha subs.�� The seeing was a 2 out of 5 and I realized that I have to work on better focus.�� The Bahtinov mask image for this scope is different than on my other scopes.�� I need to work on that.�� One thing that perplexes me is the large reflection on the bottom of the image.�� It is in the exact same place on all 5 subs and is not centered on a bright part of the image.�� It does not show on the flats.�� Could it be the field flattener?�� I thought it could be dew but the humidity was around 40%.�� Any suggestions? ��www.pbase.com/rchozick/image/153901637 ��Robert Chozickrchozick@... �� �� �� �� ��--------------- ��To UNSUBSCRIBE, or for general information on the ap-gto listsee groups.yahoo.com/group/ap-gtoYahoo Groups Links ��*> To visit your group on the web, go to:������ groups.yahoo.com/group/ap-gto/ ��*> Your email settings:������ Individual Email | Traditional ��*> To change settings online go to:������ groups.yahoo.com/group/ap-gto/join������ (Yahoo! ID required) ��*> To change settings via email:������ ap-gto-digest@yahoogroups.com ��������ap-gto-fullfeatured@yahoogroups.com ��*> To unsubscribe from this group, send an email to:������ ap-gto-unsubscribe@yahoogroups.com ��*> Your use of Yahoo Groups is subject to:������ info.yahoo.com/legal/us/yahoo/utos/terms/ ��



----------------------------

#42706 Dec 24, 2013

Boy, I sure see it!

--- In ap-gto@yahoogroups.com, chris1011@... wrote:

>

>

> I still don't see it. Anyone else see it?

>

> Roland

>



----------------------------

#42707 Dec 24, 2013

...and it doesn't require any manipulation of the contrast. Plain as day on my computer.

--- In ap-gto@yahoogroups.com, "CurtisC" calypte@...> wrote:

>

> Boy, I sure see it!

>

> --- In ap-gto@yahoogroups.com, chris1011@ wrote:

> >

> >

> > I still don't see it. Anyone else see it?

> >

> > Roland

> >

>



----------------------------

#42708 Dec 24, 2013

When I push the brightness of myscreen, I can see 3 round reflections. Probably some out of focusreflection of brighter stars out of the field of view.

Do you use any Ha filter ? If so what brand ?

Christian





Le 24/12/2013 19:54, chris1011@... a ��crit��:

I still don't see it. Anyone else seeit?��Roland-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 1:30 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead







Thanks Roland. ��The reflection is faint and looks like aring to the right of the Flame. ��I have a 15mm Baader tthread extension between the field flattener and thecamera that may be the culprit. ��It is quite possible thereflection of Alnitak on this adapter did this. ��Imodified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@...wrote:



��

A largereflection on the bottom of the image?? Canyou point to it because your image showsnothing there.

��As far as reflections, field flatteners arenot normally the source of strangereflections. One thing people forget is that acurved surface, such as those on the edge of acamera adapter or even the edge of a filter,make for nice reflective mirrors that can takestray light from a bright star near the edgeor even past the edge of the field and producea nice semi-circular arc in the field. It isgenerally an anodized surface that causesthis. Even though it is black anodize, itnevertheless can be highly reflective.Whenever you are looking for strayreflections, remove the camera and look up atthose mating surfaces near the focal plane,because that is where you will discover mostof your problems.��Rolando-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 12:41 pm

Subject: [ap-gto] First light for 155 EDFS -Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





---------------

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----------------------------

#42709 Dec 24, 2013

I created a folder under Photos and postedthe crop of the ring only. What a pain the interface has become. Try here groups.yahoo.com/neo/groups/ap-gto/photos/albums/862219043 ��-Steve ��

From:ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com ] On Behalf Of Steve Reilly

Sent: Tuesday, December 24, 20133:08 PM

To: ap-gto@yahoogroups.com

Subject: RE: [ap-gto] First lightfor 155 EDFS - Horsehead

���� It may be the ring he sees centered between the Horsehead and theFlame. It���s faint and large at this extreme stretch. The bright star isalmost to the right side of the ring. Now seeing this in the extreme stretchyou can barley see it on the first posted image. It��� at the bottom of theimage. ��Steve �� �� ��

From: ap-gto@yahoogroups.com[mailto: ap-gto@yahoogroups.com ]On Behalf Of chris1011@...

Sent: Tuesday, December 24, 20132:54 PM

To: ap-gto@yahoogroups.com

Subject: Re: [ap-gto] First lightfor 155 EDFS - Horsehead

���� I still don't see it. Anyone else see it?

��

Roland

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com >

Sent: Tue, Dec 24, 2013 1:30 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��The reflection is faint and looks like a ring to the rightof the Flame. ��I have a 15mm Baader t thread extension between the fieldflattener and the camera that may be the culprit. ��It is quite possiblethe reflection of Alnitak on this adapter did this. ��I modified the imageto show the reflection better: ��

www.pbase.com/rchozick/image/153902305

��

Robert

��On Dec 24, 2013, at 12:49 PM, chris1011@...wrote:

���� ��

A large reflection on the bottom of theimage?? Can you point to it because your image shows nothing there.

��

As far as reflections, field flattenersare not normally the source of strange reflections. One thing people forget isthat a curved surface, such as those on the edge of a camera adapter or eventhe edge of a filter, make for nice reflective mirrors that can take straylight from a bright star near the edge or even past the edge of the field andproduce a nice semi-circular arc in the field. It is generally an anodizedsurface that causes this. Even though it is black anodize, it nevertheless canbe highly reflective. Whenever you are looking for stray reflections, removethe camera and look up at those mating surfaces near the focal plane, becausethat is where you will discover most of your problems.

��

Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 12:41 pm

Subject: [ap-gto] First light for 155 EDFS - HorseheadI took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night.�� I could only get 5 - 30min Ha subs.�� The seeing was a 2 out of 5 and I realized that I have to work on better focus.�� The Bahtinov mask image for this scope is different than on my other scopes.�� I need to work on that.�� One thing that perplexes me is the large reflection on the bottom of the image.�� It is in the exact same place on all 5 subs and is not centered on a bright part of the image.�� It does not show on the flats.�� Could it be the field flattener?�� I thought it could be dew but the humidity was around 40%.�� Any suggestions? ��www.pbase.com/rchozick/image/153901637 ��Robert Chozickrchozick@... �� �� �� �� ��--------------- ��To UNSUBSCRIBE, or for general information on the ap-gto listsee groups.yahoo.com/group/ap-gtoYahoo Groups Links ��*> To visit your group on the web, go to:������ groups.yahoo.com/group/ap-gto/ ��*> Your email settings:������ Individual Email | Traditional ��*> To change settings online go to:������ groups.yahoo.com/group/ap-gto/join������ (Yahoo! ID required) ��*> To change settings via email:������ ap-gto-digest@yahoogroups.com ��������ap-gto-fullfeatured@yahoogroups.com ��*> To unsubscribe from this group, send an email to:������ ap-gto-unsubscribe@yahoogroups.com ��*> Your use of Yahoo Groups is subject to:������ info.yahoo.com/legal/us/yahoo/utos/terms/ ��



----------------------------

#42710 Dec 24, 2013

I use a Baader 7nm Ha. ��I have never seen this in any other setup I have used and I have used a lot of different scopes and adapters.

Robert

On Dec 24, 2013, at 2:13 PM, viladrich christian christian.viladrich@...> wrote:

��

When I push the brightness of myscreen, I can see 3 round reflections. Probably some out of focusreflection of brighter stars out of the field of view.

Do you use any Ha filter ? If so what brand ?

Christian





Le 24/12/2013 19:54, chris1011@... a .crit��:

I still don't see it. Anyone else seeit?��Roland-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 1:30 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead







Thanks Roland. ��The reflection is faint and looks like aring to the right of the Flame. ��I have a 15mm Baader tthread extension between the field flattener and thecamera that may be the culprit. ��It is quite possible thereflection of Alnitak on this adapter did this. ��Imodified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@...wrote:



��

A largereflection on the bottom of the image?? Canyou point to it because your image showsnothing there.

��As far as reflections, field flatteners arenot normally the source of strangereflections. One thing people forget is that acurved surface, such as those on the edge of acamera adapter or even the edge of a filter,make for nice reflective mirrors that can takestray light from a bright star near the edgeor even past the edge of the field and producea nice semi-circular arc in the field. It isgenerally an anodized surface that causesthis. Even though it is black anodize, itnevertheless can be highly reflective.Whenever you are looking for strayreflections, remove the camera and look up atthose mating surfaces near the focal plane,because that is where you will discover mostof your problems.��Rolando-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 12:41 pm

Subject: [ap-gto] First light for 155 EDFS -Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





---------------

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----------------------------

#42711 Dec 24, 2013

It'a very faint on my monitor, but I do see parts of it. Looks like a reflection of the bright star caused by two plane parallel surfaces. It is out of focus because the light has been reflected back up to the second surface and then re-directed back to the focal plane. The surfaces which are reflecting this bright star are plano-plano, so probably between a filter and the cover glass of the CCD. Such reflections are difficult or impossible to eliminate and cannot be flat fielded since they are caused by a particular bright star - which of course a flat field does not contain.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 1:56 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





My monitor's gamma must be different. ��I will check out the t thread extension.

Robert

On Dec 24, 2013, at 1:54 PM, chris1011@... wrote:



��

I still don't see it. Anyone else see it?

��Roland

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 1:30 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��The reflection is faint and looks like a ring to the right of the Flame. ��I have a 15mm Baader t thread extension between the field flattener and the camera that may be the culprit. ��It is quite possible the reflection of Alnitak on this adapter did this. ��I modified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@... wrote:

��

A large reflection on the bottom of the image?? Can you point to it because your image shows nothing there.��As far as reflections, field flatteners are not normally the source of strange reflections. One thing people forget is that a curved surface, such as those on the edge of a camera adapter or even the edge of a filter, make for nice reflective mirrors that can take stray light from a bright star near the edge or even past the edge of the field and produce a nice semi-circular arc in the field. It is generally an anodized surface that causes this. Even though it is black anodize, it nevertheless can be highly reflective. Whenever you are looking for stray reflections, remove the camera and look up at those mating surfaces near the focal plane, because that is where you will discover most of your problems.��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 12:41 pmSubject: [ap-gto] First light for 155 EDFS - Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





---------------

To UNSUBSCRIBE, or for general information on the ap-gto listsee groups.yahoo.com/group/ap-gtoYahoo Groups Links

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----------------------------

#42712 Dec 24, 2013

Bright stars can cause reflections between filter and cover glass surfaces.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 2:15 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





I use a Baader 7nm Ha. ��I have never seen this in any other setup I have used and I have used a lot of different scopes and adapters.

Robert

On Dec 24, 2013, at 2:13 PM, viladrich christian christian.viladrich@...> wrote:



��

When I push the brightness of myscreen, I can see 3 round reflections. Probably some out of focusreflection of brighter stars out of the field of view.Do you use any Ha filter ? If so what brand ?Christian

Le 24/12/2013 19:54, chris1011@... a .crit��:

I still don't see it. Anyone else seeit?��Roland-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 1:30 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��The reflection is faint and looks like aring to the right of the Flame. ��I have a 15mm Baader tthread extension between the field flattener and thecamera that may be the culprit. ��It is quite possible thereflection of Alnitak on this adapter did this. ��Imodified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@...wrote:

��

A largereflection on the bottom of the image?? Canyou point to it because your image showsnothing there.��As far as reflections, field flatteners arenot normally the source of strangereflections. One thing people forget is that acurved surface, such as those on the edge of acamera adapter or even the edge of a filter,make for nice reflective mirrors that can takestray light from a bright star near the edgeor even past the edge of the field and producea nice semi-circular arc in the field. It isgenerally an anodized surface that causesthis. Even though it is black anodize, itnevertheless can be highly reflective.Whenever you are looking for strayreflections, remove the camera and look up atthose mating surfaces near the focal plane,because that is where you will discover mostof your problems.��Rolando-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 12:41 pmSubject: [ap-gto] First light for 155 EDFS -Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





---------------

To UNSUBSCRIBE, or for general information on the ap-gto listsee groups.yahoo.com/group/ap-gtoYahoo Groups Links

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*> Your email settings: Individual Email | Traditional

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----------------------------

#42713 Dec 24, 2013

I do get halos on Alnitak but I have never seen a reflection away from it. ��Thanks for the analysis.

Robert



On Dec 24, 2013, at 2:16 PM, chris1011@... wrote:

��

Bright stars can cause reflections between filter and cover glass surfaces.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 2:15 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





I use a Baader 7nm Ha. ��I have never seen this in any other setup I have used and I have used a lot of different scopes and adapters.

Robert

On Dec 24, 2013, at 2:13 PM, viladrich christian christian.viladrich@...> wrote:



��

When I push the brightness of myscreen, I can see 3 round reflections. Probably some out of focusreflection of brighter stars out of the field of view.Do you use any Ha filter ? If so what brand ?Christian

Le 24/12/2013 19:54, chris1011@... a .crit��:

I still don't see it. Anyone else seeit?��Roland-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 1:30 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��The reflection is faint and looks like aring to the right of the Flame. ��I have a 15mm Baader tthread extension between the field flattener and thecamera that may be the culprit. ��It is quite possible thereflection of Alnitak on this adapter did this. ��Imodified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@...wrote:

��

A largereflection on the bottom of the image?? Canyou point to it because your image showsnothing there.��As far as reflections, field flatteners arenot normally the source of strangereflections. One thing people forget is that acurved surface, such as those on the edge of acamera adapter or even the edge of a filter,make for nice reflective mirrors that can takestray light from a bright star near the edgeor even past the edge of the field and producea nice semi-circular arc in the field. It isgenerally an anodized surface that causesthis. Even though it is black anodize, itnevertheless can be highly reflective.Whenever you are looking for strayreflections, remove the camera and look up atthose mating surfaces near the focal plane,because that is where you will discover mostof your problems.��Rolando-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 12:41 pmSubject: [ap-gto] First light for 155 EDFS -Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





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----------------------------

#42715 Dec 24, 2013

Interesting. ��I did notice that the rubber spacer for the filter was not centered and was poking out a small amount. ��This could make the filter slightly out of parallel to the CCD plane. ��This is great information. �� ��I will check out my filter wheel. ��Thanks, Roland.

Robert

On Dec 24, 2013, at 2:28 PM, chris1011@... wrote:

��

Halos that are centered on stars are generally caused by close parallel surfaces such as between the CCD cover glass and the chip cover. Larger reflections are caused by parallel surfaces further away, such as from filters that are some distance from the cover glass. If the filters are not perfectly parallel to the cover glass they will produce bright out-of-focus halos away from the bright star. Edge reflections from anodized surfaces produce arcs, not halos. They can be anywhere in the image.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 2:23 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





I do get halos on Alnitak but I have never seen a reflection away from it. ��Thanks for the analysis.

Robert

On Dec 24, 2013, at 2:16 PM, chris1011@... wrote:



��

Bright stars can cause reflections between filter and cover glass surfaces.

��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 2:15 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



I use a Baader 7nm Ha. ��I have never seen this in any other setup I have used and I have used a lot of different scopes and adapters.

Robert

On Dec 24, 2013, at 2:13 PM, viladrich christian christian.viladrich@...> wrote:

��

When I push the brightness of myscreen, I can see 3 round reflections. Probably some out of focusreflection of brighter stars out of the field of view.Do you use any Ha filter ? If so what brand ?Christian

Le 24/12/2013 19:54, chris1011@... a .crit��:

I still don't see it. Anyone else seeit?��Roland-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 1:30 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��The reflection is faint and looks like aring to the right of the Flame. ��I have a 15mm Baader tthread extension between the field flattener and thecamera that may be the culprit. ��It is quite possible thereflection of Alnitak on this adapter did this. ��Imodified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@...wrote:

��

A largereflection on the bottom of the image?? Canyou point to it because your image showsnothing there.��As far as reflections, field flatteners arenot normally the source of strangereflections. One thing people forget is that acurved surface, such as those on the edge of acamera adapter or even the edge of a filter,make for nice reflective mirrors that can takestray light from a bright star near the edgeor even past the edge of the field and producea nice semi-circular arc in the field. It isgenerally an anodized surface that causesthis. Even though it is black anodize, itnevertheless can be highly reflective.Whenever you are looking for strayreflections, remove the camera and look up atthose mating surfaces near the focal plane,because that is where you will discover mostof your problems.��Rolando-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 12:41 pmSubject: [ap-gto] First light for 155 EDFS -Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





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----------------------------

#42716 Dec 24, 2013

Judging by the size of the reflection circle (I'm guessing about 5mm dia on the chip), the distance between the two reflection surfaces must be around 17.5mm apart. That is less than 1 inch for sure.�� So look for two plane parallel surfaces that are this far apart to be your main culprit (most likely the Baader filter and the cover glass of your CCD. What CCD imager is this?��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 24, 2013 2:33 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





Interesting. ��I did notice that the rubber spacer for the filter was not centered and was poking out a small amount. ��This could make the filter slightly out of parallel to the CCD plane. ��This is great information. �� ��I will check out my filter wheel. ��Thanks, Roland.

Robert

On Dec 24, 2013, at 2:28 PM, chris1011@... wrote:



��

Halos that are centered on stars are generally caused by close parallel surfaces such as between the CCD cover glass and the chip cover. Larger reflections are caused by parallel surfaces further away, such as from filters that are some distance from the cover glass. If the filters are not perfectly parallel to the cover glass they will produce bright out-of-focus halos away from the bright star. Edge reflections from anodized surfaces produce arcs, not halos. They can be anywhere in the image.

��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 2:23 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



I do get halos on Alnitak but I have never seen a reflection away from it. ��Thanks for the analysis.

Robert

On Dec 24, 2013, at 2:16 PM, chris1011@... wrote:

��

Bright stars can cause reflections between filter and cover glass surfaces.��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 2:15 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



I use a Baader 7nm Ha. ��I have never seen this in any other setup I have used and I have used a lot of different scopes and adapters.

Robert

On Dec 24, 2013, at 2:13 PM, viladrich christian christian.viladrich@...> wrote:

��

When I push the brightness of myscreen, I can see 3 round reflections. Probably some out of focusreflection of brighter stars out of the field of view.Do you use any Ha filter ? If so what brand ?Christian

Le 24/12/2013 19:54, chris1011@... a .crit��:

I still don't see it. Anyone else seeit?��Roland-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 1:30 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��The reflection is faint and looks like aring to the right of the Flame. ��I have a 15mm Baader tthread extension between the field flattener and thecamera that may be the culprit. ��It is quite possible thereflection of Alnitak on this adapter did this. ��Imodified the image to show the reflection better:

www.pbase.com/rchozick/image/153902305

Robert

On Dec 24, 2013, at 12:49 PM, chris1011@...wrote:

��

A largereflection on the bottom of the image?? Canyou point to it because your image showsnothing there.��As far as reflections, field flatteners arenot normally the source of strangereflections. One thing people forget is that acurved surface, such as those on the edge of acamera adapter or even the edge of a filter,make for nice reflective mirrors that can takestray light from a bright star near the edgeor even past the edge of the field and producea nice semi-circular arc in the field. It isgenerally an anodized surface that causesthis. Even though it is black anodize, itnevertheless can be highly reflective.Whenever you are looking for strayreflections, remove the camera and look up atthose mating surfaces near the focal plane,because that is where you will discover mostof your problems.��Rolando-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Tue, Dec 24, 2013 12:41 pmSubject: [ap-gto] First light for 155 EDFS -Horsehead

I took my first light images with my 155 EDFS with the 155 field flattener and Baader Vario Finder as a guider last night. I could only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I realized that I have to work on better focus. The Bahtinov mask image for this scope is different than on my other scopes. I need to work on that. One thing that perplexes me is the large reflection on the bottom of the image. It is in the exact same place on all 5 subs and is not centered on a bright part of the image. It does not show on the flats. Could it be the field flattener? I thought it could be dew but the humidity was around 40%. Any suggestions?

www.pbase.com/rchozick/image/153901637

Robert Chozickrchozick@...





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----------------------------

#42718 Dec 24, 2013

Robert, yes I also saw it pretty clearly in the original image. This

looks to me as a straightforward 'plate-to-plate' image reflection ..

offset of course because the source of the reflection is offset ..

Alnitak!! .. and Alnitak again!! .. a glorious Mag 2 star ...

Mag 2 in the same field as one is trying to image Mag 15 objects?

At one time, in the dim and distant past .. over two decades ago ..

this would have caused serious thought, analysis, consideration, and

thereby, pretty rapidly, a solution. But I do fully appreciate that

we are now in the 'Twitter' age, no longer the age of serious

thought, analysis, consideration. So your input is well taken.



In those days we were fortunate because we did not have narrow band

filters to contend with, hence we had far fewer of these

'plate-to-plate' reflections to contend with. And I would (humbly)

question the presence of a narrow band filter at all in this field

which contains a huge, rich, and glorious amount of _broadband_! The

Flame Nebula itself contains a _huge_ amount of broadband, quite

apart from all the wonderful reflection nebulae in this field.



I would humbly submit the following (without in any way wishing to

promote it) as an example of an image (taken more than six years ago)

that allows (nearly) the full extent of the of the broadband light to

enter the CCD chip, and simultaneously removes any possibility of

'plate-to-plate' reflections:

www.astrocruise.com/milky_way/HH_0712.htm



.. sent with a slight degree of whimsical humour, but also a serious

desire to help :)

Philip

--



At 18:41 24/12/2013, you wrote: >I took my first light images with my 155 EDFS with the 155 field

>flattener and Baader Vario Finder as a guider last night. I could

>only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I

>realized that I have to work on better focus. The Bahtinov mask

>image for this scope is different than on my other scopes. I need

>to work on that. One thing that perplexes me is the large

>reflection on the bottom of the image. It is in the exact same

>place on all 5 subs and is not centered on a bright part of the

>image. It does not show on the flats. Could it be the field

>flattener? I thought it could be dew but the humidity was around

>40%. Any suggestions?

>

>www.pbase.com/rchozick/image/153901637

>

>Robert Chozick

>rchozick@...



Philip Perkins

ppml5@...>

Wiltshire UK & Luberon France

www.astrocruise.com

--

Note: the above email address may change in future.

To find my latest email address please visit: www.astrocruise.com

and click the "Send Email" link.

--



----------------------------

#42719 Dec 24, 2013

A very well written and thoughtful response. ��So unlike what we in the "twitter" world write. ��The widespread use of narrowband is due to the horrible light pollution of our cities. ��I live in a Dallas suburb and cannot produce a broadband image worth its salt. ��We are left with only narrowband imaging from our backyards. �� ��This field contains beautiful Ha data. ��I have done a wider field view with my FSQ106 in Ha:www.pbase.com/rchozick/image/148809210

and a broadband version a few years ago at a dark sky site:

www.pbase.com/rchozick/image/140227203

and I agree this is a beautiful broadband object. ��I try to go to dark sky sites at least 4 or 5 times a year.

I never had the reflection problem before. �� Your response does raise a question. �� ��Why would narrowband imaging be more likely to cause plate to plate reflections than broadband imaging?

Robert



On Dec 24, 2013, at 9:11 PM, Philip Perkins ppml5@...> wrote:

��Robert, yes I also saw it pretty clearly in the original image. This

looks to me as a straightforward 'plate-to-plate' image reflection ..

offset of course because the source of the reflection is offset ..

Alnitak!! .. and Alnitak again!! .. a glorious Mag 2 star ...

Mag 2 in the same field as one is trying to image Mag 15 objects?

At one time, in the dim and distant past .. over two decades ago ..

this would have caused serious thought, analysis, consideration, and

thereby, pretty rapidly, a solution. But I do fully appreciate that

we are now in the 'Twitter' age, no longer the age of serious

thought, analysis, consideration. So your input is well taken.



In those days we were fortunate because we did not have narrow band

filters to contend with, hence we had far fewer of these

'plate-to-plate' reflections to contend with. And I would (humbly)

question the presence of a narrow band filter at all in this field

which contains a huge, rich, and glorious amount of _broadband_! The

Flame Nebula itself contains a _huge_ amount of broadband, quite

apart from all the wonderful reflection nebulae in this field.



I would humbly submit the following (without in any way wishing to

promote it) as an example of an image (taken more than six years ago)

that allows (nearly) the full extent of the of the broadband light to

enter the CCD chip, and simultaneously removes any possibility of

'plate-to-plate' reflections:

www.astrocruise.com/milky_way/HH_0712.htm



.. sent with a slight degree of whimsical humour, but also a serious

desire to help :)

Philip

--



At 18:41 24/12/2013, you wrote:

>I took my first light images with my 155 EDFS with the 155 field

>flattener and Baader Vario Finder as a guider last night. I could

>only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I

>realized that I have to work on better focus. The Bahtinov mask

>image for this scope is different than on my other scopes. I need

>to work on that. One thing that perplexes me is the large

>reflection on the bottom of the image. It is in the exact same

>place on all 5 subs and is not centered on a bright part of the

>image. It does not show on the flats. Could it be the field

>flattener? I thought it could be dew but the humidity was around

>40%. Any suggestions?

>

>www.pbase.com/rchozick/image/153901637

>

>Robert Chozick

>rchozick@...



Philip Perkins

ppml5@...>

Wiltshire UK & Luberon France

www.astrocruise.com

--

Note: the above email address may change in future.

To find my latest email address please visit: www.astrocruise.com

and click the "Send Email" link.

--







----------------------------

#42720 Dec 25, 2013

Robert,



Thank you for your kindness. I will think about the optical

configuration that is most likely to cause this reflection, in this

position - I am sure others will help even more than I can. But

first I must apologise for the tone of my comment -- I have given

myself a strong reminder never again to get on the computer while

inebriated with pre-Christmas spirit! And a very happy one to you!



Philip

--

At 05:34 25/12/2013, you wrote:

>A very well written and thoughtful response. So unlike what we in

>the "twitter" world write. The widespread use of narrowband is due

>to the horrible light pollution of our cities. I live in a Dallas

>suburb and cannot produce a broadband image worth its salt. We are

>left with only narrowband imaging from our backyards. This field

>contains beautiful Ha data. I have done a wider field view with my

>FSQ106 in Ha:

>

>www.pbase.com/rchozick/image/148809210>www.pbase.com/rchozick/image/148809210

>

>and a broadband version a few years ago at a dark sky site:

>

>www.pbase.com/rchozick/image/140227203>www.pbase.com/rchozick/image/140227203

>

>and I agree this is a beautiful broadband object. I try to go to

>dark sky sites at least 4 or 5 times a year.

>

>I never had the reflection problem before. Your response does

>raise a question. Why would narrowband imaging be more likely to

>cause plate to plate reflections than broadband imaging?

>

>Robert





Philip Perkins

ppml5@...>

Wiltshire UK & Luberon France

www.astrocruise.com

--

Note: the above email address may change in future.

To find my latest email address please visit: www.astrocruise.com

and click the "Send Email" link.

--



----------------------------

#42722 Dec 25, 2013

Thanks. My first step will be to make sure ��my filters are flat in their wheel. The rubber spacers sometimes pop out in places. I have never had this problem before and have used this Ha filter on many other setups. ��I will probably paint the spacer also. ��Painting the filter edges seems a bit scary.��

Robert��

Sent from my iPhone

On Dec 25, 2013, at 12:30 PM, dvj@...> wrote:



��Couple of things to look for or do. ��

1. Glossy anodized����parts.�� Paint the internal surfaces��flat black.2. Reflections off the edge of the filter.���� A little flat black paint around the edges of your narrowband filters is a preventative measure. In fact, I believe that��Don��Goldman��is now doing this as standard with his filters.

How��do your broadband filters perform?�� If you suspect the 7nm HA, do some short exposures with your broadbands to see if you can reproduce the reflection.

jg



----------------------------

#42723 Dec 25, 2013

You can stick some adhesive black velvet on the edge of the filters,or better in the receiving filter holder. It is very easy to do andeffective.

Christian

-------- Message original -------- Sujet: Re: [ap-gto] First light for 155 EDFS - Horsehead Date.: Wed, 25 Dec 2013 14:52:09 -0600 De.: Robert Chozick rchozick@...> R.pondre..: ap-gto@yahoogroups.com Pour.: ap-gto@yahoogroups.com ap-gto@yahoogroups.com>





Thanks. My first step will be to make sure .my filters areflat in their wheel. The rubber spacers sometimes pop out inplaces. I have never had this problem before and have used thisHa filter on many other setups. .I will probably paint thespacer also. .Painting the filter edges seems a bit scary..

Robert.



Sent from my iPhone

On Dec 25, 2013, at 12:30 PM, dvj@...>wrote:



.Couple of things to look for or do. .

1. Glossy anodized..parts.. Paint the internalsurfaces.flat black.2. Reflections off the edge of the filter... A littleflat black paint around the edges of your narrowbandfilters is a preventative measure. In fact, I believethat.Don.Goldman.is now doing this as standard with hisfilters.

How.do your broadband filters perform?. If you suspectthe 7nm HA, do some short exposures with your broadbandsto see if you can reproduce the reflection.

jg



----------------------------

#42730 Dec 26, 2013

That's a good idea. �� Thanks. ��

Robert��

Sent from my iPhone

On Dec 25, 2013, at 11:17 PM, "Geert Vandenbulcke" geert.vandenbulcke@...> wrote:



��You don't need to paint, a flat black permanent marker pen works well to blacken the edges of filters or mirrors. ��Geert VdbulckeBelgium ��

-------- Message original -------- Sujet: Re: [ap-gto] First light for 155 EDFS - Horsehead

Date��: Wed, 25 Dec 2013 14:52:09 -0600

De��: Robert Chozick rchozick@...>

R.pondre .��: ap-gto@yahoogroups.com

Pour��: ap-gto@yahoogroups.com ap-gto@yahoogroups.com>

��Thanks. My first step will be to make sure ��my filters are flat in their wheel. The rubber spacers sometimes pop out in places. I have never had this problem before and have used this Ha filter on many other setups. ��I will probably paint the spacer also. ��Painting the filter edges seems a bit scary.��Robert��

��

Sent from my iPhone

On Dec 25, 2013, at 12:30 PM, dvj@...> wrote:

��Couple of things to look for or do. �� ��1. Glossy anodized����parts.�� Paint the internal surfaces��flat black.2. Reflections off the edge of the filter.���� A little flat black paint around the edges of your narrowband filters is a preventative measure. In fact, I believe that��Don��Goldman��is now doing this as standard with his filters. ��How��do your broadband filters perform?�� If you suspect the 7nm HA, do some short exposures with your broadbands to see if you can reproduce the reflection. ��jg �� ��







----------------------------

#42733 Dec 27, 2013

Robert,



I've had a chance to think about this a little. I use a similar

scope - 155 EDF + FF - and I have seen a similar reflection in some

of my images where there is a very bright star in the field, though

in my case the reflection is from the RGB filters. I can find some

of these images from archive, though it will take some time, going

back over a dozen years..:)



I believe this is a reflection from the surface of the filter itself,

not the filter housing. It then gets reflected back into the light

cone by the rear surface of the FF. What you are seeing, I believe,

is a reflection of Alnitak. The reason it is out of focus is due a)

to the filter not being at the image plane, b) to the greater

distance the reflected light has travelled in order to reach the

image plane, and c) to the curved surface of the rear element of the

FF. The reason the reflection is offset is because the light from

Alnitak is not at 90 deg to the filter - it strikes the filter at

some angle, and that angle is mirrored in the reflected light. In

all probability a further deflection occurs at the rear element of the FF.



Now I know all these surfaces have high anti-reflection properties

but there is a limit - none of these can stop reflections altogether,

and we are talking about a very bright star. I you shine a laser

spot onto the filter you will be able to see it reflected on a plane

surface in a darkened room.



Prevention of such reflections is not easy when you have a very

bright star in the field. The only real way is, if possible, to

change the coordinates of the image frame:

- If you move Alnitak towards the top of the frame then the

reflection should fall off the bottom edge.

- If you move Alnitak more towards the centre then the reflection

should fall on the Flame Nebula and be practically invisible.

- A thought is to have Alnitak dead centre in the frame but that will

produce a halo around Alnitak, perhaps not so good.



Whether a reflection occurs therefore depends on a few factors, the

most important of which is the presence of a bright star in the

field. My usual recourse is to digitally remove the reflection,

assuming the image is otherwise of high quality. In the case of

reflections by RGB filters this can be relatively easy, because the

reflection affects colour rather than luminosity. Therefore I may

use the clone stamp or healing brush on a colour layer (where changes

only affect the colour). This needs to be done carefully to avoid

colour artefacts in nearby objects and stars. Where the reflection

affects luminosity, as in this case, I think the repair process could

be a little more tricky but I suspect that one of the blending modes

could work quite well. I would have to experiment, sorry I don't

have much experience in this area.



I think this image is very good considering it was taken from a

heavily light polluted area. It's very unfortunate to have this

problem in a part of the world which should otherwise be excellent

for astronomy.

Philip

--



At 18:41 24/12/2013, you wrote: >I took my first light images with my 155 EDFS with the 155 field

>flattener and Baader Vario Finder as a guider last night. I could

>only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I

>realized that I have to work on better focus. The Bahtinov mask

>image for this scope is different than on my other scopes. I need

>to work on that. One thing that perplexes me is the large

>reflection on the bottom of the image. It is in the exact same

>place on all 5 subs and is not centered on a bright part of the

>image. It does not show on the flats. Could it be the field

>flattener? I thought it could be dew but the humidity was around

>40%. Any suggestions?

>

>www.pbase.com/rchozick/image/153901637

>

>Robert Chozick

>rchozick@...





Philip Perkins

ppml5@...>

Wiltshire UK & Luberon France

www.astrocruise.com

--

Note: the above email address may change in future.

To find my latest email address please visit: www.astrocruise.com

and click the "Send Email" link.

--



----------------------------

#42739 Dec 27, 2013

Thanks Philip for the thorough answer. This issue concerns me. ��So it is the field flattener that causes this. �� I need to try a different target without a bright star to properly evaluate this setup.��

Robert��

Sent from my iPhone

On Dec 27, 2013, at 7:44 AM, Philip Perkins ppml5@...> wrote:



��Robert,



I've had a chance to think about this a little. I use a similar

scope - 155 EDF + FF - and I have seen a similar reflection in some

of my images where there is a very bright star in the field, though

in my case the reflection is from the RGB filters. I can find some

of these images from archive, though it will take some time, going

back over a dozen years..:)



I believe this is a reflection from the surface of the filter itself,

not the filter housing. It then gets reflected back into the light

cone by the rear surface of the FF. What you are seeing, I believe,

is a reflection of Alnitak. The reason it is out of focus is due a)

to the filter not being at the image plane, b) to the greater

distance the reflected light has travelled in order to reach the

image plane, and c) to the curved surface of the rear element of the

FF. The reason the reflection is offset is because the light from

Alnitak is not at 90 deg to the filter - it strikes the filter at

some angle, and that angle is mirrored in the reflected light. In

all probability a further deflection occurs at the rear element of the FF.



Now I know all these surfaces have high anti-reflection properties

but there is a limit - none of these can stop reflections altogether,

and we are talking about a very bright star. I you shine a laser

spot onto the filter you will be able to see it reflected on a plane

surface in a darkened room.



Prevention of such reflections is not easy when you have a very

bright star in the field. The only real way is, if possible, to

change the coordinates of the image frame:

- If you move Alnitak towards the top of the frame then the

reflection should fall off the bottom edge.

- If you move Alnitak more towards the centre then the reflection

should fall on the Flame Nebula and be practically invisible.

- A thought is to have Alnitak dead centre in the frame but that will

produce a halo around Alnitak, perhaps not so good.



Whether a reflection occurs therefore depends on a few factors, the

most important of which is the presence of a bright star in the

field. My usual recourse is to digitally remove the reflection,

assuming the image is otherwise of high quality. In the case of

reflections by RGB filters this can be relatively easy, because the

reflection affects colour rather than luminosity. Therefore I may

use the clone stamp or healing brush on a colour layer (where changes

only affect the colour). This needs to be done carefully to avoid

colour artefacts in nearby objects and stars. Where the reflection

affects luminosity, as in this case, I think the repair process could

be a little more tricky but I suspect that one of the blending modes

could work quite well. I would have to experiment, sorry I don't

have much experience in this area.



I think this image is very good considering it was taken from a

heavily light polluted area. It's very unfortunate to have this

problem in a part of the world which should otherwise be excellent

for astronomy.

Philip

--



At 18:41 24/12/2013, you wrote:

>I took my first light images with my 155 EDFS with the 155 field

>flattener and Baader Vario Finder as a guider last night. I could

>only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I

>realized that I have to work on better focus. The Bahtinov mask

>image for this scope is different than on my other scopes. I need

>to work on that. One thing that perplexes me is the large

>reflection on the bottom of the image. It is in the exact same

>place on all 5 subs and is not centered on a bright part of the

>image. It does not show on the flats. Could it be the field

>flattener? I thought it could be dew but the humidity was around

>40%. Any suggestions?

>

>www.pbase.com/rchozick/image/153901637

>

>Robert Chozick

>rchozick@...



Philip Perkins

ppml5@...>

Wiltshire UK & Luberon France

www.astrocruise.com

--

Note: the above email address may change in future.

To find my latest email address please visit: www.astrocruise.com

and click the "Send Email" link.

--







----------------------------

#42794 Dec 30, 2013

The field flattener does not have a plano surface to reflect light. All surfaces are curved and thus will not produce this size halo. The problem is between two plano surfaces that are less than 1 inch from the focal plane. The field flattener surfaces are more than 3 inches from the focal plane. The only plano surfaces are those of the filter and the CCD cover glass, and they are less than 1 inch apart.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Fri, Dec 27, 2013 7:56 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





Thanks Philip for the thorough answer. This issue concerns me. ��So it is the field flattener that causes this. �� I need to try a different target without a bright star to properly evaluate this setup.��

Robert��



Sent from my iPhone

On Dec 27, 2013, at 7:44 AM, Philip Perkins ppml5@...> wrote:





��Robert,

I've had a chance to think about this a little. I use a similar scope - 155 EDF + FF - and I have seen a similar reflection in some of my images where there is a very bright star in the field, though in my case the reflection is from the RGB filters. I can find some of these images from archive, though it will take some time, going back over a dozen years..:)

I believe this is a reflection from the surface of the filter itself, not the filter housing. It then gets reflected back into the light cone by the rear surface of the FF. What you are seeing, I believe, is a reflection of Alnitak. The reason it is out of focus is due a) to the filter not being at the image plane, b) to the greater distance the reflected light has travelled in order to reach the image plane, and c) to the curved surface of the rear element of the FF. The reason the reflection is offset is because the light from Alnitak is not at 90 deg to the filter - it strikes the filter at some angle, and that angle is mirrored in the reflected light. In all probability a further deflection occurs at the rear element of the FF.

Now I know all these surfaces have high anti-reflection properties but there is a limit - none of these can stop reflections altogether, and we are talking about a very bright star. I you shine a laser spot onto the filter you will be able to see it reflected on a plane surface in a darkened room.

Prevention of such reflections is not easy when you have a very bright star in the field. The only real way is, if possible, to change the coordinates of the image frame:- If you move Alnitak towards the top of the frame then the reflection should fall off the bottom edge.- If you move Alnitak more towards the centre then the reflection should fall on the Flame Nebula and be practically invisible.- A thought is to have Alnitak dead centre in the frame but that will produce a halo around Alnitak, perhaps not so good.

Whether a reflection occurs therefore depends on a few factors, the most important of which is the presence of a bright star in the field. My usual recourse is to digitally remove the reflection, assuming the image is otherwise of high quality. In the case of reflections by RGB filters this can be relatively easy, because the reflection affects colour rather than luminosity. Therefore I may use the clone stamp or healing brush on a colour layer (where changes only affect the colour). This needs to be done carefully to avoid colour artefacts in nearby objects and stars. Where the reflection affects luminosity, as in this case, I think the repair process could be a little more tricky but I suspect that one of the blending modes could work quite well. I would have to experiment, sorry I don't have much experience in this area.

I think this image is very good considering it was taken from a heavily light polluted area. It's very unfortunate to have this problem in a part of the world which should otherwise be excellent for astronomy.Philip--

At 18:41 24/12/2013, you wrote:>I took my first light images with my 155 EDFS with the 155 field >flattener and Baader Vario Finder as a guider last night. I could >only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I >realized that I have to work on better focus. The Bahtinov mask >image for this scope is different than on my other scopes. I need >to work on that. One thing that perplexes me is the large >reflection on the bottom of the image. It is in the exact same >place on all 5 subs and is not centered on a bright part of the >image. It does not show on the flats. Could it be the field >flattener? I thought it could be dew but the humidity was around >40%. Any suggestions?>>www.pbase.com/rchozick/image/153901637>>Robert Chozick>rchozick@...

Philip Perkinsppml5@...>Wiltshire UK & Luberon Francewww.astrocruise.com--Note: the above email address may change in future.To find my latest email address please visit: www.astrocruise.comand click the "Send Email" link.--



----------------------------

#42800 Dec 30, 2013

What you did is fine for stray light, but it will not do anything to eliminate filter reflections off the actual filter surfaces. They will still be there just as before. ��I don't think you understand filter reflections. Here is a good article describing just how they occur and how to determine the surfaces that contribute to them by measuring their diameters on your image:��www.astrodon.com/articles_faq/articles_faq/press_release:391,355,49��You can see by this article that these halos and reflection circles have nothing to do with the edges of the optics in a CCD camera, rather they have everything to do with the coatings that are placed on the optical surfaces.��By the way, I have replaced most of my filters, especially the narrow band ones, with Astrodon True Balance filters. This has pretty much eliminated all reflection halos that I used to get with other filter types.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Mon, Dec 30, 2013 8:02 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





Thanks Roland. ��I darkened my filter edges, painted the inside of the 15mm t-thread adapter flat black and I double checked that the shiny side of my Baader filters faced away from the sensor. �� When I get a chance i am going to test on the same Horsehead-Alnitak image with Ha to see if I can reproduce the reflection. ��Needless to say I am hoping I cannot reproduce it. ��Everything is sure clean now.

Robert



On Dec 30, 2013, at 10:16 AM, chris1011@... wrote:



��

The field flattener does not have a plano surface to reflect light. All surfaces are curved and thus will not produce this size halo. The problem is between two plano surfaces that are less than 1 inch from the focal plane. The field flattener surfaces are more than 3 inches from the focal plane. The only plano surfaces are those of the filter and the CCD cover glass, and they are less than 1 inch apart.

��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Fri, Dec 27, 2013 7:56 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Philip for the thorough answer. This issue concerns me. ��So it is the field flattener that causes this. �� I need to try a different target without a bright star to properly evaluate this setup.��

Robert��

Sent from my iPhone

On Dec 27, 2013, at 7:44 AM, Philip Perkins ppml5@...> wrote:

��Robert,

I've had a chance to think about this a little. I use a similar scope - 155 EDF + FF - and I have seen a similar reflection in some of my images where there is a very bright star in the field, though in my case the reflection is from the RGB filters. I can find some of these images from archive, though it will take some time, going back over a dozen years..:)

I believe this is a reflection from the surface of the filter itself, not the filter housing. It then gets reflected back into the light cone by the rear surface of the FF. What you are seeing, I believe, is a reflection of Alnitak. The reason it is out of focus is due a) to the filter not being at the image plane, b) to the greater distance the reflected light has travelled in order to reach the image plane, and c) to the curved surface of the rear element of the FF. The reason the reflection is offset is because the light from Alnitak is not at 90 deg to the filter - it strikes the filter at some angle, and that angle is mirrored in the reflected light. In all probability a further deflection occurs at the rear element of the FF.

Now I know all these surfaces have high anti-reflection properties but there is a limit - none of these can stop reflections altogether, and we are talking about a very bright star. I you shine a laser spot onto the filter you will be able to see it reflected on a plane surface in a darkened room.

Prevention of such reflections is not easy when you have a very bright star in the field. The only real way is, if possible, to change the coordinates of the image frame:- If you move Alnitak towards the top of the frame then the reflection should fall off the bottom edge.- If you move Alnitak more towards the centre then the reflection should fall on the Flame Nebula and be practically invisible.- A thought is to have Alnitak dead centre in the frame but that will produce a halo around Alnitak, perhaps not so good.

Whether a reflection occurs therefore depends on a few factors, the most important of which is the presence of a bright star in the field. My usual recourse is to digitally remove the reflection, assuming the image is otherwise of high quality. In the case of reflections by RGB filters this can be relatively easy, because the reflection affects colour rather than luminosity. Therefore I may use the clone stamp or healing brush on a colour layer (where changes only affect the colour). This needs to be done carefully to avoid colour artefacts in nearby objects and stars. Where the reflection affects luminosity, as in this case, I think the repair process could be a little more tricky but I suspect that one of the blending modes could work quite well. I would have to experiment, sorry I don't have much experience in this area.

I think this image is very good considering it was taken from a heavily light polluted area. It's very unfortunate to have this problem in a part of the world which should otherwise be excellent for astronomy.Philip--

At 18:41 24/12/2013, you wrote:>I took my first light images with my 155 EDFS with the 155 field >flattener and Baader Vario Finder as a guider last night. I could >only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I >realized that I have to work on better focus. The Bahtinov mask >image for this scope is different than on my other scopes. I need >to work on that. One thing that perplexes me is the large >reflection on the bottom of the image. It is in the exact same >place on all 5 subs and is not centered on a bright part of the >image. It does not show on the flats. Could it be the field >flattener? I thought it could be dew but the humidity was around >40%. Any suggestions?>>www.pbase.com/rchozick/image/153901637>>Robert Chozick>rchozick@...

Philip Perkinsppml5@...>Wiltshire UK & Luberon Francewww.astrocruise.com--Note: the above email address may change in future.To find my latest email address please visit: www.astrocruise.comand click the "Send Email" link.--







----------------------------

#42801 Dec 30, 2013

I also replaced all my Baader filters with Astrodon. More expensive but you

get what you pay for.. And Don is great! The new exoplanet filter looks

intriguing.







Dave Goodyear



KB2 Networks Inc.



214 Main St. #318



El Segundo, CA 90245



310-933-2436







cid:image001.png@01CB2D84.4D351AD0











From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of

chris1011@...

Sent: Monday, December 30, 2013 6:30 PM

To: ap-gto@yahoogroups.com

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead











What you did is fine for stray light, but it will not do anything to

eliminate filter reflections off the actual filter surfaces. They will still

be there just as before.







I don't think you understand filter reflections. Here is a good article

describing just how they occur and how to determine the surfaces that

contribute to them by measuring their diameters on your image:







www.astrodon.com/articles_faq/articles_faq/press_release:391,355,49







You can see by this article that these halos and reflection circles have

nothing to do with the edges of the optics in a CCD camera, rather they have

everything to do with the coatings that are placed on the optical surfaces.







By the way, I have replaced most of my filters, especially the narrow band

ones, with Astrodon True Balance filters. This has pretty much eliminated

all reflection halos that I used to get with other filter types.







Rolando



-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Mon, Dec 30, 2013 8:02 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead







Thanks Roland. I darkened my filter edges, painted the inside of the 15mm

t-thread adapter flat black and I double checked that the shiny side of my

Baader filters faced away from the sensor. When I get a chance i am going

to test on the same Horsehead-Alnitak image with Ha to see if I can

reproduce the reflection. Needless to say I am hoping I cannot reproduce

it. Everything is sure clean now.







Robert









On Dec 30, 2013, at 10:16 AM, chris1011@... wrote:















The field flattener does not have a plano surface to reflect light. All

surfaces are curved and thus will not produce this size halo. The problem is

between two plano surfaces that are less than 1 inch from the focal plane.

The field flattener surfaces are more than 3 inches from the focal plane.

The only plano surfaces are those of the filter and the CCD cover glass, and

they are less than 1 inch apart.







Rolando



-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Fri, Dec 27, 2013 7:56 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead







Thanks Philip for the thorough answer. This issue concerns me. So it is the

field flattener that causes this. I need to try a different target without

a bright star to properly evaluate this setup.



Robert







Sent from my iPhone





On Dec 27, 2013, at 7:44 AM, Philip Perkins ppml5@...> wrote:







Robert,



I've had a chance to think about this a little. I use a similar

scope - 155 EDF + FF - and I have seen a similar reflection in some

of my images where there is a very bright star in the field, though

in my case the reflection is from the RGB filters. I can find some

of these images from archive, though it will take some time, going

back over a dozen years..:)



I believe this is a reflection from the surface of the filter itself,

not the filter housing. It then gets reflected back into the light

cone by the rear surface of the FF. What you are seeing, I believe,

is a reflection of Alnitak. The reason it is out of focus is due a)

to the filter not being at the image plane, b) to the greater

distance the reflected light has travelled in order to reach the

image plane, and c) to the curved surface of the rear element of the

FF. The reason the reflection is offset is because the light from

Alnitak is not at 90 deg to the filter - it strikes the filter at

some angle, and that angle is mirrored in the reflected light. In

all probability a further deflection occurs at the rear element of the FF.



Now I know all these surfaces have high anti-reflection properties

but there is a limit - none of these can stop reflections altogether,

and we are talking about a very bright star. I you shine a laser

spot onto the filter you will be able to see it reflected on a plane

surface in a darkened room.



Prevention of such reflections is not easy when you have a very

bright star in the field. The only real way is, if possible, to

change the coordinates of the image frame:

- If you move Alnitak towards the top of the frame then the

reflection should fall off the bottom edge.

- If you move Alnitak more towards the centre then the reflection

should fall on the Flame Nebula and be practically invisible.

- A thought is to have Alnitak dead centre in the frame but that will

produce a halo around Alnitak, perhaps not so good.



Whether a reflection occurs therefore depends on a few factors, the

most important of which is the presence of a bright star in the

field. My usual recourse is to digitally remove the reflection,

assuming the image is otherwise of high quality. In the case of

reflections by RGB filters this can be relatively easy, because the

reflection affects colour rather than luminosity. Therefore I may

use the clone stamp or healing brush on a colour layer (where changes

only affect the colour). This needs to be done carefully to avoid

colour artefacts in nearby objects and stars. Where the reflection

affects luminosity, as in this case, I think the repair process could

be a little more tricky but I suspect that one of the blending modes

could work quite well. I would have to experiment, sorry I don't

have much experience in this area.



I think this image is very good considering it was taken from a

heavily light polluted area. It's very unfortunate to have this

problem in a part of the world which should otherwise be excellent

for astronomy.

Philip

--



At 18:41 24/12/2013, you wrote:

>I took my first light images with my 155 EDFS with the 155 field

>flattener and Baader Vario Finder as a guider last night. I could

>only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I

>realized that I have to work on better focus. The Bahtinov mask

>image for this scope is different than on my other scopes. I need

>to work on that. One thing that perplexes me is the large

>reflection on the bottom of the image. It is in the exact same

>place on all 5 subs and is not centered on a bright part of the

>image. It does not show on the flats. Could it be the field

>flattener? I thought it could be dew but the humidity was around

>40%. Any suggestions?

>

>www.pbase.com/rchozick/image/153901637

>

>Robert Chozick

>rchozick@...



Philip Perkins

ppml5@...>

Wiltshire UK & Luberon France

www.astrocruise.com www.astrocruise.com/>

--

Note: the above email address may change in future.

To find my latest email address please visit: www.astrocruise.com

www.astrocruise.com/>

and click the "Send Email" link.

--















Robert Chozick



rchozick@...



























[Non-text portions of this message have been removed]







----------------------------

#42803 Dec 31, 2013

Thanks Roland. �� I will replace the filters with Astrodon. ��It was on my list to do eventually anyway. �� My only question is why this reflection halo did not show up before on other telescope configurations. ��My only thought would be that it took Alnitak being in that exact position to maximize the halo. ��Would you agree?

Robert

On Dec 30, 2013, at 8:29 PM, chris1011@... wrote:

��

What you did is fine for stray light, but it will not do anything to eliminate filter reflections off the actual filter surfaces. They will still be there just as before. ��I don't think you understand filter reflections. Here is a good article describing just how they occur and how to determine the surfaces that contribute to them by measuring their diameters on your image:��www.astrodon.com/articles_faq/articles_faq/press_release:391,355,49��You can see by this article that these halos and reflection circles have nothing to do with the edges of the optics in a CCD camera, rather they have everything to do with the coatings that are placed on the optical surfaces.��By the way, I have replaced most of my filters, especially the narrow band ones, with Astrodon True Balance filters. This has pretty much eliminated all reflection halos that I used to get with other filter types.��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Mon, Dec 30, 2013 8:02 pm

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





Thanks Roland. ��I darkened my filter edges, painted the inside of the 15mm t-thread adapter flat black and I double checked that the shiny side of my Baader filters faced away from the sensor. �� When I get a chance i am going to test on the same Horsehead-Alnitak image with Ha to see if I can reproduce the reflection. ��Needless to say I am hoping I cannot reproduce it. ��Everything is sure clean now.

Robert



On Dec 30, 2013, at 10:16 AM, chris1011@... wrote:



��

The field flattener does not have a plano surface to reflect light. All surfaces are curved and thus will not produce this size halo. The problem is between two plano surfaces that are less than 1 inch from the focal plane. The field flattener surfaces are more than 3 inches from the focal plane. The only plano surfaces are those of the filter and the CCD cover glass, and they are less than 1 inch apart.

��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Fri, Dec 27, 2013 7:56 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Philip for the thorough answer. This issue concerns me. ��So it is the field flattener that causes this. �� I need to try a different target without a bright star to properly evaluate this setup.��

Robert��

Sent from my iPhone

On Dec 27, 2013, at 7:44 AM, Philip Perkins ppml5@...> wrote:

��Robert,

I've had a chance to think about this a little. I use a similar scope - 155 EDF + FF - and I have seen a similar reflection in some of my images where there is a very bright star in the field, though in my case the reflection is from the RGB filters. I can find some of these images from archive, though it will take some time, going back over a dozen years..:)

I believe this is a reflection from the surface of the filter itself, not the filter housing. It then gets reflected back into the light cone by the rear surface of the FF. What you are seeing, I believe, is a reflection of Alnitak. The reason it is out of focus is due a) to the filter not being at the image plane, b) to the greater distance the reflected light has travelled in order to reach the image plane, and c) to the curved surface of the rear element of the FF. The reason the reflection is offset is because the light from Alnitak is not at 90 deg to the filter - it strikes the filter at some angle, and that angle is mirrored in the reflected light. In all probability a further deflection occurs at the rear element of the FF.

Now I know all these surfaces have high anti-reflection properties but there is a limit - none of these can stop reflections altogether, and we are talking about a very bright star. I you shine a laser spot onto the filter you will be able to see it reflected on a plane surface in a darkened room.

Prevention of such reflections is not easy when you have a very bright star in the field. The only real way is, if possible, to change the coordinates of the image frame:- If you move Alnitak towards the top of the frame then the reflection should fall off the bottom edge.- If you move Alnitak more towards the centre then the reflection should fall on the Flame Nebula and be practically invisible.- A thought is to have Alnitak dead centre in the frame but that will produce a halo around Alnitak, perhaps not so good.

Whether a reflection occurs therefore depends on a few factors, the most important of which is the presence of a bright star in the field. My usual recourse is to digitally remove the reflection, assuming the image is otherwise of high quality. In the case of reflections by RGB filters this can be relatively easy, because the reflection affects colour rather than luminosity. Therefore I may use the clone stamp or healing brush on a colour layer (where changes only affect the colour). This needs to be done carefully to avoid colour artefacts in nearby objects and stars. Where the reflection affects luminosity, as in this case, I think the repair process could be a little more tricky but I suspect that one of the blending modes could work quite well. I would have to experiment, sorry I don't have much experience in this area.

I think this image is very good considering it was taken from a heavily light polluted area. It's very unfortunate to have this problem in a part of the world which should otherwise be excellent for astronomy.Philip--

At 18:41 24/12/2013, you wrote:>I took my first light images with my 155 EDFS with the 155 field >flattener and Baader Vario Finder as a guider last night. I could >only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I >realized that I have to work on better focus. The Bahtinov mask >image for this scope is different than on my other scopes. I need >to work on that. One thing that perplexes me is the large >reflection on the bottom of the image. It is in the exact same >place on all 5 subs and is not centered on a bright part of the >image. It does not show on the flats. Could it be the field >flattener? I thought it could be dew but the humidity was around >40%. Any suggestions?>>www.pbase.com/rchozick/image/153901637>>Robert Chozick>rchozick@...

Philip Perkinsppml5@...>Wiltshire UK & Luberon Francewww.astrocruise.com--Note: the above email address may change in future.To find my latest email address please visit: www.astrocruise.comand click the "Send Email" link.--







----------------------------

#42804 Dec 31, 2013

Reflections need a bright object in or just outside of the the field and the proper alignment of the participating surfaces. They can happen anywhere on the sky the required elements are present. As to the filters, why bother changing them out? Until you beat the imaging/processing curve into submission and then start getting really good at manipulating images, it just isn't worth the significant additional cost. Like you said, reflections usually don't happen, are subdued enough to be missed, or of no consequence. Once you really learn the art of producing pretty pictures, then it might be worth taking that next step.Just my opinion mind you.



----------------------------

#42806 Dec 31, 2013

The link to the Ha image didn't work correctly:www.pbase.com/rchozick/image/148809210



On Dec 31, 2013, at 1:29 PM, Robert Chozick rchozick@...> wrote:

��

I feel that I am far enough along the curve that I want to remove any variables in the way. ��It is hard enough to fight seeing, weather and dark sky time. ��The cost of the Astrodon filters is really not that much when you consider what we have all paid for mounts and scopes. ��I am only buying the LRGB and 5nm Ha for now. ��I will keep my Baader OIII and SII and sell the other filters on A-Mart. ��I hardly ever use the OIII and SII. ��If I start doing more narrowband in OIII and SII I will replace those eventually. I have certainly had a lot of halos on my FSQ 106. ��I am hoping these will get better with the Astrodon. ��Even in the Veil I had some halos with the FSQ:

www.pbase.com/rchozick/image/151781448

and on the Horsehead with the FSQ in Ha:

www.pbase.com/rchozick/image/148809210

Robert









On Dec 31, 2013, at 11:19 AM, JunkMailGoesHere@...> wrote:

��Reflections need a bright object in or just outside of the the field and the proper alignment of the participating surfaces. They can happen anywhere on the sky the required elements are present. As to the filters, why bother changing them out? Until you beat the imaging/processing curve into submission and then start getting really good at manipulating images, it just isn't worth the significant additional cost. Like you said, reflections usually don't happen, are subdued enough to be missed, or of no consequence. Once you really learn the art of producing pretty pictures, then it might be worth taking that next step.Just my opinion mind you.



----------------------------

#42815 Jan 2, 2014

I cannot agree to anything without being able to analyze the systems that you imaged with. Being that I'm here and you are there, I can only rely on what is in your posts, and therefore it is all speculation on my part. However, I have seen all this before, and I know the likely culprits.��Rolando��

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 31, 2013 9:40 am

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead





Thanks Roland. �� I will replace the filters with Astrodon. ��It was on my list to do eventually anyway. �� My only question is why this reflection halo did not show up before on other telescope configurations. ��My only thought would be that it took Alnitak being in that exact position to maximize the halo. ��Would you agree?

Robert

On Dec 30, 2013, at 8:29 PM, chris1011@... wrote:



��

What you did is fine for stray light, but it will not do anything to eliminate filter reflections off the actual filter surfaces. They will still be there just as before.

��I don't think you understand filter reflections. Here is a good article describing just how they occur and how to determine the surfaces that contribute to them by measuring their diameters on your image:��www.astrodon.com/articles_faq/articles_faq/press_release:391,355,49��You can see by this article that these halos and reflection circles have nothing to do with the edges of the optics in a CCD camera, rather they have everything to do with the coatings that are placed on the optical surfaces.��By the way, I have replaced most of my filters, especially the narrow band ones, with Astrodon True Balance filters. This has pretty much eliminated all reflection halos that I used to get with other filter types.��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Mon, Dec 30, 2013 8:02 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Roland. ��I darkened my filter edges, painted the inside of the 15mm t-thread adapter flat black and I double checked that the shiny side of my Baader filters faced away from the sensor. �� When I get a chance i am going to test on the same Horsehead-Alnitak image with Ha to see if I can reproduce the reflection. ��Needless to say I am hoping I cannot reproduce it. ��Everything is sure clean now.

Robert



On Dec 30, 2013, at 10:16 AM, chris1011@... wrote:

��

The field flattener does not have a plano surface to reflect light. All surfaces are curved and thus will not produce this size halo. The problem is between two plano surfaces that are less than 1 inch from the focal plane. The field flattener surfaces are more than 3 inches from the focal plane. The only plano surfaces are those of the filter and the CCD cover glass, and they are less than 1 inch apart.��Rolando

-----Original Message-----From: Robert Chozick rchozick@...>To: ap-gto ap-gto@yahoogroups.com>Sent: Fri, Dec 27, 2013 7:56 pmSubject: Re: [ap-gto] First light for 155 EDFS - Horsehead



Thanks Philip for the thorough answer. This issue concerns me. ��So it is the field flattener that causes this. �� I need to try a different target without a bright star to properly evaluate this setup.��

Robert��

Sent from my iPhone

On Dec 27, 2013, at 7:44 AM, Philip Perkins ppml5@...> wrote:

��Robert,

I've had a chance to think about this a little. I use a similar scope - 155 EDF + FF - and I have seen a similar reflection in some of my images where there is a very bright star in the field, though in my case the reflection is from the RGB filters. I can find some of these images from archive, though it will take some time, going back over a dozen years..:)

I believe this is a reflection from the surface of the filter itself, not the filter housing. It then gets reflected back into the light cone by the rear surface of the FF. What you are seeing, I believe, is a reflection of Alnitak. The reason it is out of focus is due a) to the filter not being at the image plane, b) to the greater distance the reflected light has travelled in order to reach the image plane, and c) to the curved surface of the rear element of the FF. The reason the reflection is offset is because the light from Alnitak is not at 90 deg to the filter - it strikes the filter at some angle, and that angle is mirrored in the reflected light. In all probability a further deflection occurs at the rear element of the FF.

Now I know all these surfaces have high anti-reflection properties but there is a limit - none of these can stop reflections altogether, and we are talking about a very bright star. I you shine a laser spot onto the filter you will be able to see it reflected on a plane surface in a darkened room.

Prevention of such reflections is not easy when you have a very bright star in the field. The only real way is, if possible, to change the coordinates of the image frame:- If you move Alnitak towards the top of the frame then the reflection should fall off the bottom edge.- If you move Alnitak more towards the centre then the reflection should fall on the Flame Nebula and be practically invisible.- A thought is to have Alnitak dead centre in the frame but that will produce a halo around Alnitak, perhaps not so good.

Whether a reflection occurs therefore depends on a few factors, the most important of which is the presence of a bright star in the field. My usual recourse is to digitally remove the reflection, assuming the image is otherwise of high quality. In the case of reflections by RGB filters this can be relatively easy, because the reflection affects colour rather than luminosity. Therefore I may use the clone stamp or healing brush on a colour layer (where changes only affect the colour). This needs to be done carefully to avoid colour artefacts in nearby objects and stars. Where the reflection affects luminosity, as in this case, I think the repair process could be a little more tricky but I suspect that one of the blending modes could work quite well. I would have to experiment, sorry I don't have much experience in this area.

I think this image is very good considering it was taken from a heavily light polluted area. It's very unfortunate to have this problem in a part of the world which should otherwise be excellent for astronomy.Philip--

At 18:41 24/12/2013, you wrote:>I took my first light images with my 155 EDFS with the 155 field >flattener and Baader Vario Finder as a guider last night. I could >only get 5 - 30min Ha subs. The seeing was a 2 out of 5 and I >realized that I have to work on better focus. The Bahtinov mask >image for this scope is different than on my other scopes. I need >to work on that. One thing that perplexes me is the large >reflection on the bottom of the image. It is in the exact same >place on all 5 subs and is not centered on a bright part of the >image. It does not show on the flats. Could it be the field >flattener? I thought it could be dew but the humidity was around >40%. Any suggestions?>>www.pbase.com/rchozick/image/153901637>>Robert Chozick>rchozick@...

Philip Perkinsppml5@...>Wiltshire UK & Luberon Francewww.astrocruise.com--Note: the above email address may change in future.To find my latest email address please visit: www.astrocruise.comand click the "Send Email" link.--







----------------------------

#42818 Jan 2, 2014

I will just see what happens with the new filters. ��Thanks everyone for all the advice.

Robert

On Jan 2, 2014, at 10:16 AM, viladrich christian christian.viladrich@...> wrote:

��

Hi Robert,



It all depends on what are actually your other scopeconfigurations (F/D ratio, exposure time, field of view ... toname a few).



Christian



Le 02/01/2014 16:10, chris1011@... a .crit��:

I cannot agreeto anything without being able to analyze the systems thatyou imaged with. Being that I'm here and you are there, Ican only rely on what is in your posts, and therefore it isall speculation on my part. However, I have seen all thisbefore, and I know the likely culprits.��Rolando��-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Dec 31, 2013 9:40 am

Subject: Re: [ap-gto] First light for 155 EDFS - Horsehead







Thanks Roland. �� I will replace the filters with Astrodon.��It was on my list to do eventually anyway. �� My onlyquestion is why this reflection halo did not show upbefore on other telescope configurations. ��My only thoughtwould be that it took Alnitak being in that exact positionto maximize the halo. ��Would you agree?

Robert

On Dec 30, 2013, at 8:29 PM, chris1011@...wrote:



��

What youdid is fine for stray light, but it will notdo anything to eliminate filter reflectionsoff the actual filter surfaces. They willstill be there just as before.

��I don't think you understand filterreflections. Here is a good article describingjust how they occur and how to determine thesurfaces that contribute to them by measuringtheir diameters on your image:��www.astrodon.com/articles_faq/articles_faq/press_release:391,355,49��You can see by this article that thesehalos and reflection circles have nothing todo with the edges of the optics in a CCDcamera, rather they have everything to do withthe coatings that are placed on the opticalsurfaces.��By the way, I have replaced most of myfilters, especially the narrow band ones, withAstrodon True Balance filters. This has prettymuch eliminated all reflection halos that Iused to get with other filter types.��Rolando-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Mon, Dec 30, 2013 8:02 pm

Subject: Re: [ap-gto] First light for 155 EDFS- Horsehead







Thanks Roland. ��I darkened my filteredges, painted the inside of the 15mmt-thread adapter flat black and I doublechecked that the shiny side of my Baaderfilters faced away from the sensor. �� WhenI get a chance i am going to test on thesame Horsehead-Alnitak image with Ha tosee if I can reproduce the reflection.��Needless to say I am hoping I cannotreproduce it. ��Everything is sure cleannow.

Robert



On Dec 30, 2013, at 10:16 AM, chris1011@...wrote:



��

Thefield flattener does nothave a plano surface toreflect light. All surfacesare curved and thus will notproduce this size halo. Theproblem is between two planosurfaces that are less than1 inch from the focal plane.The field flattener surfacesare more than 3 inches fromthe focal plane. The onlyplano surfaces are those ofthe filter and the CCD coverglass, and they are lessthan 1 inch apart.

��Rolando-----OriginalMessage-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Fri, Dec 27, 2013 7:56pm

Subject: Re: [ap-gto] Firstlight for 155 EDFS -Horsehead





Thanks Philip forthe thorough answer.This issue concernsme. ��So it is thefield flattener thatcauses this. �� I needto try a differenttarget without abright star toproperly evaluate thissetup.��

Robert��



Sent from my iPhone

On Dec 27, 2013, at7:44 AM, PhilipPerkins ppml5@...> wrote:



��Robert,



I've had achance to thinkabout this alittle. I use asimilar

scope - 155 EDF+ FF - and Ihave seen asimilarreflection insome

of my imageswhere there is avery bright starin the field,though

in my case thereflection isfrom the RGBfilters. I canfind some

of these imagesfrom archive,though it willtake some time,going

back over adozen years..:)



I believe thisis a reflectionfrom the surfaceof the filteritself,

not the filterhousing. It thengets reflectedback into thelight

cone by the rearsurface of theFF. What you areseeing, Ibelieve,

is a reflectionof Alnitak. Thereason it is outof focus is duea)

to the filternot being at theimage plane, b)to the greater

distance thereflected lighthas travelled inorder to reachthe

image plane, andc) to the curvedsurface of therear element ofthe

FF. The reasonthe reflectionis offset isbecause thelight from

Alnitak is notat 90 deg to thefilter - itstrikes thefilter at

some angle, andthat angle ismirrored in thereflected light.In

all probabilitya furtherdeflectionoccurs at therear element ofthe FF.



Now I know allthese surfaceshave highanti-reflectionproperties

but there is alimit - none ofthese can stopreflectionsaltogether,

and we aretalking about avery brightstar. I youshine a laser

spot onto thefilter you willbe able to seeit reflected ona plane

surface in adarkened room.



Prevention ofsuch reflectionsis not easy whenyou have a very

bright star inthe field. Theonly real wayis, if possible,to

change thecoordinates ofthe image frame:

- If you moveAlnitak towardsthe top of theframe then the

reflectionshould fall offthe bottom edge.

- If you moveAlnitak moretowards thecentre then thereflection

should fall onthe Flame Nebulaand bepracticallyinvisible.

- A thought isto have Alnitakdead centre inthe frame butthat will

produce a haloaround Alnitak,perhaps not sogood.



Whether areflectionoccurs thereforedepends on a fewfactors, the

most importantof which is thepresence of abright star inthe

field. My usualrecourse is todigitally removethe reflection,

assuming theimage isotherwise ofhigh quality. Inthe case of

reflections byRGB filters thiscan berelatively easy,because the

reflectionaffects colourrather thanluminosity.Therefore I may

use the clonestamp or healingbrush on acolour layer(where changes

only affect thecolour). Thisneeds to be donecarefully toavoid

colour artefactsin nearbyobjects andstars. Where thereflection

affectsluminosity, asin this case, Ithink the repairprocess could

be a little moretricky but Isuspect that oneof the blendingmodes

could work quitewell. I wouldhave toexperiment,sorry I don't

have muchexperience inthis area.



I think thisimage is verygood consideringit was takenfrom a

heavily lightpolluted area.It's veryunfortunate tohave this

problem in apart of theworld whichshould otherwisebe excellent

for astronomy.

Philip

--



At 18:4124/12/2013, youwrote:

>I took myfirst lightimages with my155 EDFS withthe 155 field

>flattenerand Baader VarioFinder as aguider lastnight. I could

>only get 5 -30min Ha subs.The seeing was a2 out of 5 and I

>realizedthat I have towork on betterfocus. TheBahtinov mask

>image forthis scope isdifferent thanon my otherscopes. I need

>to work onthat. One thingthat perplexesme is the large

>reflectionon the bottom ofthe image. It isin the exactsame

>place on all5 subs and isnot centered ona bright part ofthe

>image. Itdoes not show onthe flats. Couldit be the field

>flattener? Ithought it couldbe dew but thehumidity wasaround

>40%. Anysuggestions?

>

>www.pbase.com/rchozick/image/153901637

>

>RobertChozick

>rchozick@...



Philip Perkins

ppml5@...>

Wiltshire UK& LuberonFrance

www.astrocruise.com

--

Note: the aboveemail addressmay change infuture.

To find mylatest emailaddress pleasevisit: www.astrocruise.com

and click the"Send Email"link.

--







----------------------------

#43663 Apr 13, 2014

I finally got to take my new AP 155 EDFS to a dark sky location and got my first (dark) light on the Leo Triplet. I am looking forward to using this telescope.



I got to go to NEAF for the first time and really enjoyed meeting Roland and the gang.



www.pbase.com/rchozick/image/155198647



Robert Chozick

rchozick@...



----------------------------

#43666 Apr 14, 2014

Superb Robert!Don A On Monday, April 14, 2014 7:00:32 AM, Doug LeGrand vet-blk@...> wrote:

��Fabulous!!!



----------------------------

#43668 Apr 14, 2014

Thanks Doug.

Robert

On Apr 14, 2014, at 8:00 AM, Doug LeGrand vet-blk@...> wrote:

��

Fabulous!!!



----------------------------

#43671 Apr 15, 2014

Great image!��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Mon, Apr 14, 2014 12:28 am

Subject: [ap-gto] First light in dark location with 155 EDFS

I finally got to take my new AP 155 EDFS to a dark sky location and got my first (dark) light on the Leo Triplet. I am looking forward to using this telescope.

I got to go to NEAF for the first time and really enjoyed meeting Roland and the gang.

www.pbase.com/rchozick/image/155198647

Robert Chozickrchozick@...





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----------------------------

#43682 Apr 15, 2014

Thanks Don and Roland

Roland, after your great explanation at NEAF of the simple method of polar alignment, when I put my Mach 1 back in its backyard placement I will try it out. ��I basically understood it from the manual but explaining the theory helped a lot. ��I prefer theory explanations over detailed procedures.

Robert

On Apr 15, 2014, at 4:26 PM, chris1011@... wrote:

��

Great image!��Rolando

-----Original Message-----

From: Robert Chozick rchozick@...>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Mon, Apr 14, 2014 12:28 am

Subject: [ap-gto] First light in dark location with 155 EDFS

I finally got to take my new AP 155 EDFS to a dark sky location and got my first (dark) light on the Leo Triplet. I am looking forward to using this telescope.

I got to go to NEAF for the first time and really enjoyed meeting Roland and the gang.

www.pbase.com/rchozick/image/155198647

Robert Chozickrchozick@...





---------------

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----------------------------

#44136 Jun 5, 2014

I just wanted to mention how gorgeous the planets are in the 155. I was looking at the Moon, Mars and Saturn tonight and they were unbelievable. I could see 5 of Saturn's moons, great detail on the cloud bands and the bottom poking out below the rings. I could see a lot of detail on Mars and the poles and the Moon's surface is so detailed. You really created a wonderful scope. I unfortunately have not had much time to image with it. Looking forward to that.



Robert Chozick

rchozick@...



----------------------------

#44137 Jun 5, 2014

Great! Glad you like it.��Rolando����-----Original Message-----

From: Robert Chozick rchozick@... [ap-gto] ap-gto@yahoogroups.com>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Fri, Jun 6, 2014 12:57 am

Subject: [ap-gto] Planets in a 155 EDFS

I just wanted to mention how gorgeous the planets are in the 155. I was looking at the Moon, Mars and Saturn tonight and they were unbelievable. I could see 5 of Saturn's moons, great detail on the cloud bands and the bottom poking out below the rings. I could see a lot of detail on Mars and the poles and the Moon's surface is so detailed. You really created a wonderful scope. I unfortunately have not had much time to image with it. Looking forward to that.

Robert Chozickrchozick@...





---------------Posted by: Robert Chozick rchozick@...>---------------

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----------------------------

#44143 Jun 6, 2014

One other note. I had left the refractor tracking on my Mach 1 for two hours with a 5mm eyepiece in it and when I came back Mars was still in the middle of the eyepiece.��

Robert��

Sent from my iPhone

On Jun 6, 2014, at 1:00 AM, "chris1011@... [ap-gto]" ap-gto@yahoogroups.com> wrote:



��

Great! Glad you like it.��Rolando����-----Original Message-----

From: Robert Chozick rchozick@... [ap-gto] ap-gto@yahoogroups.com>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Fri, Jun 6, 2014 12:57 am

Subject: [ap-gto] Planets in a 155 EDFS

I just wanted to mention how gorgeous the planets are in the 155. I was looking at the Moon, Mars and Saturn tonight and they were unbelievable. I could see 5 of Saturn's moons, great detail on the cloud bands and the bottom poking out below the rings. I could see a lot of detail on Mars and the poles and the Moon's surface is so detailed. You really created a wonderful scope. I unfortunately have not had much time to image with it. Looking forward to that.

Robert Chozickrchozick@...





---------------Posted by: Robert Chozick rchozick@...>---------------

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----------------------------

#48591 Aug 9, 2015

I have listed my AP 155 EDFS for sale on Astromart under classified #893521 if anyone is interested.



Robert Chozick

rchozick@...



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