Re: added a photo of the rig Re: [ap-ug] Re: First Light: AP155EDF f/7 and PL39000C, Target M8/M20


Jun 21, 2009

 


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

#45764 Jun 21, 2009

to my website so you can see the rig



www.narrowbandimaging.com/m8_m20_ap155_pl39K_page.htm





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

From: Rick K

To: ap-ug@yahoogroups.com

Sent: Sunday, June 21, 2009 5:29 PM

Subject: [ap-ug] Re: First Light: AP155EDF f/7 and PL39000C, Target M8/M20











I took a peak at the low-res version which forced me to have a look at the high-res 39MP version. It is really nice! Great stars right to the corners. I see that you are using an ST7 as a guider with the venerable AP 80mm with rings. I don't see any flexure creeping in at all. Were you staying on one side of the mount (scope eastside?) for all of the subs?



I see that there are some internal reflection haloes on the west and north side brightest stars (CCD cover / luminance filter or luminance filter / field flattener), but the blue haloes not due to reflections do not seem to be nearly as bright as they were with the 180. Very interesting!



Rick.



--- In ap-ug@yahoogroups.com, "Richard Crisp" rdcrisp@...> wrote:

>

> I have been attempting to use the '155 f/7 with the PL39K for three weeks now. The faster focal ratio, f/7 versus the f/9 of the '180edt, means nearly a 2x improvement in light gathering rate with a modest increase in image scale: 1.15 versus 0.87 "/pixel. Finally the weather cooperated on Saturday night.

>

> I took 4.75 hours of exposure on Sat night using 15 minute subexposures.

>

> the full 39 megapixel resolution on the linked page below is interesting: there are a lot of stars in there!

>

> www.narrowbandimaging.com/m8_m20_ap155_pl39K_page.htm

>

>

>

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

>











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



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

#45795 Jun 22, 2009

Hi Richard,



Thanks for the update with the pics of the 155 and 180 setups. They look eerily familiar ;-)



I have the AP guidescope but have been using a Traveler instead locked to the rings of the 180 or 155 on an AP DOVE15 assembly and using an ATIK 16IC as a guiding camera. I am going to give a Borg 45 a go in a couple of weeks to see if it works out. I can see that I might have to give the AP guidescope a go as well. I would like to see the Borg scope work out as it is very light and small but whichever works best is the one that will be used. The second reason I want to get away from the Traveler is that I want to use it as a visual scope when the bigger aperture is imaging and vice versa.



So, what do you think about the blue haloes? I think the 155 appears to be slightly better corrected in the blue/violet end of the spectrum. I wonder if the 180 is pre FPL53 - maybe FPL52? Still an awesome telescope. That slight excess blue would be totally invisible visually. Are you auto-focusing between each of the exposures? One problem I have is tube shrinkage and/or optical focus shift due to temperature changes during the night. It necessitates a re-focus between exposures, even if it is just a sequence of luminance or just a sequence of Ha. Any optical focus shift might shift the shorter wavelength more than longer wavelengths or just might be more noticeable on these ultra-sensitive CCD's?



Rick.



--- In ap-ug@yahoogroups.com, "Richard Crisp" rdcrisp@...> wrote:

>

> to my website so you can see the rig

>

> www.narrowbandimaging.com/m8_m20_ap155_pl39K_page.htm

>

>

>

> ----- Original Message -----

> From: Rick K

> To: ap-ug@yahoogroups.com

> Sent: Sunday, June 21, 2009 5:29 PM

> Subject: [ap-ug] Re: First Light: AP155EDF f/7 and PL39000C, Target M8/M20

>

>

>

>

>

> I took a peak at the low-res version which forced me to have a look at the high-res 39MP version. It is really nice! Great stars right to the corners. I see that you are using an ST7 as a guider with the venerable AP 80mm with rings. I don't see any flexure creeping in at all. Were you staying on one side of the mount (scope eastside?) for all of the subs?

>

> I see that there are some internal reflection haloes on the west and north side brightest stars (CCD cover / luminance filter or luminance filter / field flattener), but the blue haloes not due to reflections do not seem to be nearly as bright as they were with the 180. Very interesting!

>

> Rick.

>

> --- In ap-ug@yahoogroups.com, "Richard Crisp" rdcrisp@> wrote:

> >

> > I have been attempting to use the '155 f/7 with the PL39K for three weeks now. The faster focal ratio, f/7 versus the f/9 of the '180edt, means nearly a 2x improvement in light gathering rate with a modest increase in image scale: 1.15 versus 0.87 "/pixel. Finally the weather cooperated on Saturday night.

> >

> > I took 4.75 hours of exposure on Sat night using 15 minute subexposures.

> >

> > the full 39 megapixel resolution on the linked page below is interesting: there are a lot of stars in there!

> >

> > www.narrowbandimaging.com/m8_m20_ap155_pl39K_page.htm

> >

> >

> >

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

> >

>

>

>

>

>

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

>







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

#45796 Jun 22, 2009

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

From: Rick K

To: ap-ug@yahoogroups.com

Sent: Monday, June 22, 2009 6:15 PM

Subject: added a photo of the rig Re: [ap-ug] Re: First Light: AP155EDF f/7 and PL39000C, Target M8/M20











Hi Richard,



Thanks for the update with the pics of the 155 and 180 setups. They look eerily familiar ;-)



I have the AP guidescope but have been using a Traveler instead locked to the rings of the 180 or 155 on an AP DOVE15 assembly and using an ATIK 16IC as a guiding camera. I am going to give a Borg 45 a go in a couple of weeks to see if it works out. I can see that I might have to give the AP guidescope a go as well. I would like to see the Borg scope work out as it is very light and small but whichever works best is the one that will be used. The second reason I want to get away from the Traveler is that I want to use it as a visual scope when the bigger aperture is imaging and vice versa.



So, what do you think about the blue haloes? I think the 155 appears to be slightly better corrected in the blue/violet end of the spectrum. I wonder if the 180 is pre FPL53 - maybe FPL52? Still an awesome telescope. That slight excess blue would be totally invisible visually. Are you auto-focusing between each of the exposures? One problem I have is tube shrinkage and/or optical focus shift due to temperature changes during the night. It necessitates a re-focus between exposures, even if it is just a sequence of luminance or just a sequence of Ha. Any optical focus shift might shift the shorter wavelength more than longer wavelengths or just might be more noticeable on these ultra-sensitive CCD's?



Rick.



--

thanks for the comments Rick



The camera is one shot color. I am not given the opportunity to focus between color shots.



I focused twice on Sat night: once before shooting and once an hour and a half later. I had been monitoring the temperature and it was pretty constant for me so i went to bed at 1am and got up at 4:15 to wrap things up.



The 180 I have is one of the last made. I have no idea about glass types though.



As for the blue haloes there are lots of factors to consider. Probably the key one is how I process the data. I tend to stretch each color separately to get what I want in the nebula and background. That can cause bloating in one channel different than others. That may all there is to it.



Because it is a one shot color sensor and since Kodak's color filter arrays leak NIR and each color leaks it a bit differently, you need to use an IR cut filter to prevent that from desaturating and skewing your color blend. I am using a 50x50 luminance filter from Baader circa 2007. I have no idea if this is current production or not and am not sure about its UV characteristics.



It may be implicated in some of the reflections and sometimes reflections can give the appearance of haloes, particularly in slow optical systems where the light rays are more parallel than in fast ones. Toss in a field flattener and you have a nice curved surface well situated to assist in the reflections.



Then there's a cover slip on the sensor and a camera window too in the optical path.



I've seen peculiar reflections from slow systems that are not seen in fast ones. For a fast system the optical cone is very sharp so after a reflection it is very divergent so the energy is spread so far you don't notice it. For a slow system that may not be true. That's one example of things to consider.



I have made no attempts to isolate the cause if any, of the haloes. Again they don't bother me really and I suspect they are more to do with processing than any other single factor. But a simple thing to do is to remove the carousel from the filter wheel and see how it works with no filters at all. That is easy to do and usually doesn't put filters so much at risk from handling as removing them from the carousels. I dislike handling filters unless absolutely necessary!



Until I shot the OSC with the '180 I really didn't do anything else with it except for emission line imaging. I don't recall ever shooting any color sequential RGB images using a monochrome sensor so I really cannot comment on whether or not it featured haloes in conventional RGB made with monochrome sensors.



I didn't see anything about it unusual when shooting emission line images in color.















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



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

#45800 Jun 22, 2009

--- In ap-ug@yahoogroups.com, "Richard Crisp" rdcrisp@...> wrote:

> --

> thanks for the comments Rick

>

> The camera is one shot color. I am not given the opportunity to focus between color shots.



Are you running Maxim to control the camera? There should be a way to focus between each sub, although, if, as you say, the temperature is pretty stable once it has cooled off from the daytime heat, re-focus is probably not necessary and a waste of imaging time.



If your 180 is one of the last then it should be FPL53 although only Roland knows for sure :-)





>

> I focused twice on Sat night: once before shooting and once an hour and a half later. I had been monitoring the temperature and it was pretty constant for me so i went to bed at 1am and got up at 4:15 to wrap things up.

>

> The 180 I have is one of the last made. I have no idea about glass types though.



Hopefully the luminance filter won't act as a UV dispersion lens. It doesn't seem likely that it would although I guess anything is possible. This is for selfish reasons as well, since I have the same Baader filters with close to the same camera, filter wheel and scope setups.



I am hoping that the interaction between the luminance filter and either the coverslip of the CCD or the field flattener is the culprit for the larger haloes around the brightest stars. An option to check would be to invert the filter and see what happens with these reflection haloes. Is the window of the CCD AR coated? I just had my 16803 camera updated with an AR coated window. Since your camera is pretty new I would expect that it already has this but one never knows. I am hoping that the Baader filters are AR coated on both sides but I have a sinking feeling that they may not be. They would probably work best with the AR coating facing the CCD if they are only coated on one side. The distance from the CCD to the back of the field flattener or TCC is quite a ways and, combined with the curvature of the rear lens of the flatter or telecompressor, any reflections would probably not be discretely imaged as you mention below. They would be spread out well over the chip.



I am just looking at doing my best to eliminate as many problems as possible prior to starting my next imaging session. The nights are rather short up here at this time of the year north of the 49th, and making the most of imaging time is mandatory. Knowing the specifics of your imaging train is very helpful.



Rick.

>

> As for the blue haloes there are lots of factors to consider. Probably the key one is how I process the data. I tend to stretch each color separately to get what I want in the nebula and background. That can cause bloating in one channel different than others. That may all there is to it.

>

> Because it is a one shot color sensor and since Kodak's color filter arrays leak NIR and each color leaks it a bit differently, you need to use an IR cut filter to prevent that from desaturating and skewing your color blend. I am using a 50x50 luminance filter from Baader circa 2007. I have no idea if this is current production or not and am not sure about its UV characteristics.



>

> It may be implicated in some of the reflections and sometimes reflections can give the appearance of haloes, particularly in slow optical systems where the light rays are more parallel than in fast ones. Toss in a field flattener and you have a nice curved surface well situated to assist in the reflections.



>

> Then there's a cover slip on the sensor and a camera window too in the optical path.

>

> I've seen peculiar reflections from slow systems that are not seen in fast ones. For a fast system the optical cone is very sharp so after a reflection it is very divergent so the energy is spread so far you don't notice it. For a slow system that may not be true. That's one example of things to consider.

>

> I have made no attempts to isolate the cause if any, of the haloes. Again they don't bother me really and I suspect they are more to do with processing than any other single factor. But a simple thing to do is to remove the carousel from the filter wheel and see how it works with no filters at all. That is easy to do and usually doesn't put filters so much at risk from handling as removing them from the carousels. I dislike handling filters unless absolutely necessary!

>

> Until I shot the OSC with the '180 I really didn't do anything else with it except for emission line imaging. I don't recall ever shooting any color sequential RGB images using a monochrome sensor so I really cannot comment on whether or not it featured haloes in conventional RGB made with monochrome sensors.

>

> I didn't see anything about it unusual when shooting emission line images in color.

>

>

>

>

>

>

>

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

>







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

#45803 Jun 22, 2009

well an easy thing to do is to pop the carousel out....



I hate to do that because I don't want to lose a night of imaging right now....



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

From: Rick K

To: ap-ug@yahoogroups.com

Sent: Monday, June 22, 2009 8:30 PM

Subject: added a photo of the rig Re: [ap-ug] Re: First Light: AP155EDF f/7 and PL39000C, Target M8/M20











--- In ap-ug@yahoogroups.com, "Richard Crisp" rdcrisp@...> wrote:



> --

> thanks for the comments Rick

>

> The camera is one shot color. I am not given the opportunity to focus between color shots.



Are you running Maxim to control the camera? There should be a way to focus between each sub, although, if, as you say, the temperature is pretty stable once it has cooled off from the daytime heat, re-focus is probably not necessary and a waste of imaging time.



If your 180 is one of the last then it should be FPL53 although only Roland knows for sure :-)



>

> I focused twice on Sat night: once before shooting and once an hour and a half later. I had been monitoring the temperature and it was pretty constant for me so i went to bed at 1am and got up at 4:15 to wrap things up.

>

> The 180 I have is one of the last made. I have no idea about glass types though.



Hopefully the luminance filter won't act as a UV dispersion lens. It doesn't seem likely that it would although I guess anything is possible. This is for selfish reasons as well, since I have the same Baader filters with close to the same camera, filter wheel and scope setups.



I am hoping that the interaction between the luminance filter and either the coverslip of the CCD or the field flattener is the culprit for the larger haloes around the brightest stars. An option to check would be to invert the filter and see what happens with these reflection haloes. Is the window of the CCD AR coated? I just had my 16803 camera updated with an AR coated window. Since your camera is pretty new I would expect that it already has this but one never knows. I am hoping that the Baader filters are AR coated on both sides but I have a sinking feeling that they may not be. They would probably work best with the AR coating facing the CCD if they are only coated on one side. The distance from the CCD to the back of the field flattener or TCC is quite a ways and, combined with the curvature of the rear lens of the flatter or telecompressor, any reflections would probably not be discretely imaged as you mention below. They would be spread out well over the chip.



I am just looking at doing my best to eliminate as many problems as possible prior to starting my next imaging session. The nights are rather short up here at this time of the year north of the 49th, and making the most of imaging time is mandatory. Knowing the specifics of your imaging train is very helpful.



Rick.



>

> As for the blue haloes there are lots of factors to consider. Probably the key one is how I process the data. I tend to stretch each color separately to get what I want in the nebula and background. That can cause bloating in one channel different than others. That may all there is to it.

>

> Because it is a one shot color sensor and since Kodak's color filter arrays leak NIR and each color leaks it a bit differently, you need to use an IR cut filter to prevent that from desaturating and skewing your color blend. I am using a 50x50 luminance filter from Baader circa 2007. I have no idea if this is current production or not and am not sure about its UV characteristics.



>

> It may be implicated in some of the reflections and sometimes reflections can give the appearance of haloes, particularly in slow optical systems where the light rays are more parallel than in fast ones. Toss in a field flattener and you have a nice curved surface well situated to assist in the reflections.



>

> Then there's a cover slip on the sensor and a camera window too in the optical path.

>

> I've seen peculiar reflections from slow systems that are not seen in fast ones. For a fast system the optical cone is very sharp so after a reflection it is very divergent so the energy is spread so far you don't notice it. For a slow system that may not be true. That's one example of things to consider.

>

> I have made no attempts to isolate the cause if any, of the haloes. Again they don't bother me really and I suspect they are more to do with processing than any other single factor. But a simple thing to do is to remove the carousel from the filter wheel and see how it works with no filters at all. That is easy to do and usually doesn't put filters so much at risk from handling as removing them from the carousels. I dislike handling filters unless absolutely necessary!

>

> Until I shot the OSC with the '180 I really didn't do anything else with it except for emission line imaging. I don't recall ever shooting any color sequential RGB images using a monochrome sensor so I really cannot comment on whether or not it featured haloes in conventional RGB made with monochrome sensors.

>

> I didn't see anything about it unusual when shooting emission line images in color.

>

>

>

>

>

>

>

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

>











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







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

#45837 Jun 25, 2009

Awesome setup Richard!



One nit I will pick.



AP has a very nice black anodized bracket available for the Robofocus

that will eliminate that huge erector set looking contraption you

have that detracts from the beauty of the telescope. ;-)



Mark

On Jun 21, 2009, at 8:58 PM, Richard Crisp wrote:



> to my website so you can see the rig

>

> www.narrowbandimaging.com/m8_m20_ap155_pl39K_page.htm







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



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