VintageBigBlue.org

 

Re: [Losmandy_users] Re: PERIODIC ERROR PIC


Oct 5, 2000

 


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

#542 Oct 5, 2000

Hi Folks:

I've posted a .jpg under the "files" section to illustrate why

I've been asking about bearings, worms, etc. I have a permanent pier

setup in an observatory and have done some astrophotography but I've

been unable to get my G-11 to track accurately enough to do imaging.

My setup consists of an ST4 guiding through a Pronto guidescope

piggy-backed on a Tak FS128. The ST4/G11 combo has produced volumes

of quality astrophotos and after researching, I knew that was the way

to go. Unfortunately, my G-11 can't keep the guidestar in the box so

the ST4 has large errors.

I've contacted Scott and he asked me to ship my worm gear and

bearing blocks to him so that he can check it out. He sent me a

replacement to use, but the error is as bad as the one that I sent

him. I've been actively following the threads on replacing the

worm bearings, as well as adding additional needle bearings in the RA

and DEC axes and have ordered these (for $110.00)!

The photo I posted is a 4 minutes exposure taken through a

Starlight Xpress HX516 with the FS128 at prime focus with the G11

head

offset from it's polar alignment to better show the error. I'm

confident Scott will help resolve the problem and I'm really looking

forward to doing some imaging with the setup.



Regards,

Bruce Inscoe



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

#545 Oct 5, 2000

Bruce Inscoe wrote:

> I've contacted Scott and he asked me to ship my worm gear and

> bearing blocks to him so that he can check it out. He sent me a

> replacement to use, but the error is as bad as the one that I sent

> him. I've been actively following the threads on replacing the

> worm bearings, as well as adding additional needle bearings in the RA

> and DEC axes and have ordered these (for $110.00)!



Bruce,



Where did you order your parts from? I just ordered the same (or similar)

parts from McMaster-Carr and the total was something like $28 + shipping.







--

Jim Girard

www.teleport.com/~argo



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

#546 Oct 6, 2000

--- In Losmandy_users@egroups.com, Jim Girard argo@t...> wrote: > Bruce Inscoe wrote:

>

> > I've contacted Scott and he asked me to ship my worm gear and

> > bearing blocks to him so that he can check it out. He sent me a

> > replacement to use, but the error is as bad as the one that I sent

> > him. I've been actively following the threads on replacing the

> > worm bearings, as well as adding additional needle bearings in

the

RA > > and DEC axes and have ordered these (for $110.00)!

>

> Bruce,

>

> Where did you order your parts from? I just ordered the same (or

similar) > parts from McMaster-Carr and the total was something like $28 +

shipping.



Jim:

I ordered grade 7 (highest precision) stainless steel bearings

(4)

for both worms and one 1.250" needle bearing for the RA axis from Les

at Nordic Bearing in Canada. I got this info from Jimmy Thibert on a

posting within the group.



Regards,

Bruce Inscoe



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

#548 Oct 6, 2000

I can't help but notice that the periodic error is not smooth as

would be expected if you had gear runout or the worm was not

perfectly round. Could it be perhaps the stepper motors that cause

this problem? It would be interesting to try to swap the stepper

motor with an ac synchronic motor which has I believe the same shaft

and mounting holes. One of the 1 rpm motors from hurst. If you then

get smooth periodic error, you have eliminated the stepper as the

culprit.

On another note, I see many members saying they get 2's and 1's

followed by 5's and 7's on their ST4's. I have the same behavior

with a 990mm guide scope but all my photos show perfect tracking

though my 1000mm main scope (45 minutes shots blown up to 8x10). Is

there really an issue here or is this like the "audiophile" syndrome

where we are always trying to perfect something close to perfection?

Regards, Tom Blahovici







--- In Losmandy_users@egroups.com, "Bruce Inscoe"

midniterider@m...> wrote: > --- In Losmandy_users@egroups.com, Jim Girard argo@t...> wrote:

> > Bruce Inscoe wrote:

> >

> > > I've contacted Scott and he asked me to ship my worm gear

and > > > bearing blocks to him so that he can check it out. He sent me a

> > > replacement to use, but the error is as bad as the one that I

sent > > > him. I've been actively following the threads on replacing the

> > > worm bearings, as well as adding additional needle bearings in

> the

> RA

> > > and DEC axes and have ordered these (for $110.00)!

> >

> > Bruce,

> >

> > Where did you order your parts from? I just ordered the same (or

> similar)

> > parts from McMaster-Carr and the total was something like $28 +

> shipping.

>

> Jim:

> I ordered grade 7 (highest precision) stainless steel bearings

> (4)

> for both worms and one 1.250" needle bearing for the RA axis from

Les > at Nordic Bearing in Canada. I got this info from Jimmy Thibert on

a > posting within the group.

>

> Regards,

> Bruce Inscoe







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

#549 Oct 6, 2000

Hi Bruce,



I recently purchased a G-11 mount (two weeks ago). When the mount

arrived, I installed the DSC's and other accys. Two days later the

scope arrived (an FS128G). I took the setup out into the driveway to

test everything. The mount would not track well, if at all. That

Friday

night my local club had an all night outing. I was hoping one of the

other members who had more experience with a polar mount might be

able

to help. We tried and tried, but not much luck. When we did get the

mount to track, objects would "bounce" very badly. Totally unusable

for

imaging.



The following Monday I called the dealer (Anacortes) and talked

the

problem over with them. They contacted Scott Losmandy and after many

phone calls they had me call Scott directly. After describing the

problem first hand to Scott he finally said "it sounds like you have

the DSC gear on the RA shaft too tight. You want about two

thicknesses

of paper clearence between the gear and the thick washer". Well, I

went

out and re-adjusted the gear, set the mount up without the scope or

counter weight and it tracked well, not perfect but much better (.2

degrees deviation in 4 hours). I then left the OTA off and just hung

the counter weight on it. It still tracked for another hour. By this

time it was midnight and Jupiter and Saturn were coming up off the

horizon. I opened the garage door and sighted Jupiter. The only

movement now was atmospheric. Turning the mount on/off made no

difference in the image steadyness, unlike before. The "bounce" for

me

was induced by the stepper motors.



I am anxiously awaiting a night when I can test the mount with a

camera. It was a nice experience to have both the dealer and the

manufacturer so interested in making the mount work. Dont's know if

this might help your situation.



Good Luck, and keep us posted



Kevin Walsh



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

#550 Oct 6, 2000

--- In Losmandy_users@egroups.com, tblahovici@l... wrote: > I can't help but notice that the periodic error is not smooth as

> would be expected if you had gear runout or the worm was not

> perfectly round. Could it be perhaps the stepper motors that cause

> this problem? It would be interesting to try to swap the stepper

> motor with an ac synchronic motor which has I believe the same

shaft > and mounting holes. One of the 1 rpm motors from hurst. If you

then > get smooth periodic error, you have eliminated the stepper as the

> culprit.

> On another note, I see many members saying they get 2's and 1's

> followed by 5's and 7's on their ST4's. I have the same behavior

> with a 990mm guide scope but all my photos show perfect tracking

> though my 1000mm main scope (45 minutes shots blown up to 8x10). Is

> there really an issue here or is this like the "audiophile"

syndrome > where we are always trying to perfect something close to perfection?

> Regards, Tom Blahovici



Tom:

I have swapped both motors and worms several times...no change.

Most users of the G11/ST4 combo, guiding at 1/2 meter focal length,

report long strings of 0's and 1's with maybe an occasional 2. At 1

meter, these values would be doubled. If an error of 3 or above

occurs, it will show up in image. At a one meter focal length, which

is pretty much what you have, then maybe a 5 is OK. At one meter on

my G11/ST4, it can't keep the star in the box and I get E's in RA.

Imaging through an FS128 at prime focus, and guided with the ST4, out

of twenty, 2-minute exposures, I may get 2 that don't show elongated

stars. I know that the G11 is capable of far better.



Regards,

Bruce Inscoe



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

#551 Oct 6, 2000

Kevin:

Visually, I can't see any "bounce" at 312X, but I do see fairly

rapid drift back and forth in RA (east/west). The picture I posted

of

the error will show what I mean. I DO appreciate the tip on the DSC

washers, and I will give it a try. What have I got to loose?



Regards,

Bruce Inscoe





In Losmandy_users@egroups.com, kw@d... wrote: > Hi Bruce,

>

> I recently purchased a G-11 mount (two weeks ago). When the

mount > arrived, I installed the DSC's and other accys. Two days later the

> scope arrived (an FS128G). I took the setup out into the driveway

to > test everything. The mount would not track well, if at all. That

> Friday

> night my local club had an all night outing. I was hoping one of

the > other members who had more experience with a polar mount might be

> able

> to help. We tried and tried, but not much luck. When we did get the

> mount to track, objects would "bounce" very badly. Totally unusable

> for

> imaging.

>

> The following Monday I called the dealer (Anacortes) and talked

> the

> problem over with them. They contacted Scott Losmandy and after

many > phone calls they had me call Scott directly. After describing the

> problem first hand to Scott he finally said "it sounds like you

have > the DSC gear on the RA shaft too tight. You want about two

> thicknesses

> of paper clearence between the gear and the thick washer". Well, I

> went

> out and re-adjusted the gear, set the mount up without the scope or

> counter weight and it tracked well, not perfect but much better (.2

> degrees deviation in 4 hours). I then left the OTA off and just

hung > the counter weight on it. It still tracked for another hour. By

this > time it was midnight and Jupiter and Saturn were coming up off the

> horizon. I opened the garage door and sighted Jupiter. The only

> movement now was atmospheric. Turning the mount on/off made no

> difference in the image steadyness, unlike before. The "bounce" for

> me

> was induced by the stepper motors.

>

> I am anxiously awaiting a night when I can test the mount with

a > camera. It was a nice experience to have both the dealer and the

> manufacturer so interested in making the mount work. Dont's know if

> this might help your situation.

>

> Good Luck, and keep us posted

>

> Kevin Walsh







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

#552 Oct 6, 2000

tblahovici@...-ingelheim.com wrote:

> On another note, I see many members saying they get 2's and 1's

> followed by 5's and 7's on their ST4's. I have the same behavior

> with a 990mm guide scope but all my photos show perfect tracking

> though my 1000mm main scope (45 minutes shots blown up to 8x10). Is

> there really an issue here or is this like the "audiophile" syndrome

> where we are always trying to perfect something close to perfection?



My mount has similar behaviour and it does show up on the CCD images

as slightly elongated stars. However, film (at least the color film I

use) is far more forgiving to the slight eccentricities of the mount,

stars are always round under the same guiding conditions.

Out at ARGO, where I observe with 5 other astronomers, I can watch the

AP 1200 and the Paramount mounts track nearly perfectly all night.

They do get an occassional jump, which I guess is seeing induced, as

they are not periodic and are quite rare.

When I get my G-11 all tuned up, properly balanced for the situation

and the parameters in MaxIM just right, I can get very good results.

The problem is, I do not know how to repeatedly get the mount tuned

up, there is always a bit of hit and miss. But, I am getting closer

all the time.



For images taken with the G-11, see my web page and look at the 4"

Takahashi images.



Tom Carrico

www.proaxis.com/~carrico



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

#553 Oct 6, 2000

Tom:

My setup is on a permanent pier/observatory so I won't have to

worry about the "hit and miss" of a portable setup. Most others

using

the ST4/Gll combo report errors of 0's and 1's and sometimes maybe a

2. My G11/ST4 at 1/2 meter guiding focal length starts out fine, but

within three cycles (using 3 second updates) the errors go to 4 and

5.

At 1 meter (doubles) I get E's because the star goes out of the box.

This shows up in CCD, as well as film images, which prevents me from

using the G11 for astrophotography, which is what I purchased it for

after researching and found that this combo (ST4/G11)was the way to

go. If others will post pictures of their RA error, you'll see that

most are pretty much straight lines. I'm not doing the audiophile

syndrome of trying to find perfection in something that's already

perfect, just trying to make the mount perform like it should.



Regards,

Bruce Inscoe



>

>

> tblahovici@l... wrote:

>

> > On another note, I see many members saying they get 2's and 1's

> > followed by 5's and 7's on their ST4's. I have the same behavior

> > with a 990mm guide scope but all my photos show perfect tracking

> > though my 1000mm main scope (45 minutes shots blown up to 8x10).

Is > > there really an issue here or is this like the "audiophile"

syndrome > > where we are always trying to perfect something close to

perfection? >

> My mount has similar behaviour and it does show up on the CCD images

> as slightly elongated stars. However, film (at least the color film

I > use) is far more forgiving to the slight eccentricities of the

mount, > stars are always round under the same guiding conditions.

> Out at ARGO, where I observe with 5 other astronomers, I can watch

the > AP 1200 and the Paramount mounts track nearly perfectly all night.

> They do get an occassional jump, which I guess is seeing induced, as

> they are not periodic and are quite rare.

> When I get my G-11 all tuned up, properly balanced for the situation

> and the parameters in MaxIM just right, I can get very good results.

> The problem is, I do not know how to repeatedly get the mount tuned

> up, there is always a bit of hit and miss. But, I am getting closer

> all the time.

>

> For images taken with the G-11, see my web page and look at the 4"

> Takahashi images.

>

> Tom Carrico

> www.proaxis.com/~carrico



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

#554 Oct 6, 2000

Hi Tom:



I think the effect of PE is lower as you go up in declination, just the same

way the RA motor seem to go slower as

you up in declination, any error seem to affect photographs less near the

pole zone than in the ecuatorial zone.





Regards



Starry nights for everyone



Jose Lumbreras







>I can't help but notice that the periodic error is not smooth as

>would be expected if you had gear runout or the worm was not

>perfectly round. Could it be perhaps the stepper motors that cause

>this problem? It would be interesting to try to swap the stepper

>motor with an ac synchronic motor which has I believe the same shaft

>and mounting holes. One of the 1 rpm motors from hurst. If you then

>get smooth periodic error, you have eliminated the stepper as the

>culprit.

>On another note, I see many members saying they get 2's and 1's

>followed by 5's and 7's on their ST4's. I have the same behavior

>with a 990mm guide scope but all my photos show perfect tracking

>though my 1000mm main scope (45 minutes shots blown up to 8x10). Is

>there really an issue here or is this like the "audiophile" syndrome

>where we are always trying to perfect something close to perfection?

>Regards, Tom Blahovici

>

>

>

>--- In Losmandy_users@egroups.com, "Bruce Inscoe"

>midniterider@m...> wrote:

>> --- In Losmandy_users@egroups.com, Jim Girard argo@t...> wrote:

>> > Bruce Inscoe wrote:

>> >

>> > > I've contacted Scott and he asked me to ship my worm gear

>and

>> > > bearing blocks to him so that he can check it out. He sent me a

>> > > replacement to use, but the error is as bad as the one that I

>sent

>> > > him. I've been actively following the threads on replacing the

>> > > worm bearings, as well as adding additional needle bearings in

>> the

>> RA

>> > > and DEC axes and have ordered these (for $110.00)!

>> >

>> > Bruce,

>> >

>> > Where did you order your parts from? I just ordered the same (or

>> similar)

>> > parts from McMaster-Carr and the total was something like $28 +

>> shipping.

>>

>> Jim:

>> I ordered grade 7 (highest precision) stainless steel bearings

>> (4)

>> for both worms and one 1.250" needle bearing for the RA axis from

>Les

>> at Nordic Bearing in Canada. I got this info from Jimmy Thibert on

>a

>> posting within the group.

>>

>> Regards,

>> Bruce Inscoe

>

>

>To unsubscribe from this group, send an email to:

>Losmandy_users-unsubscribe@egroups.com

>

>

>

>







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

#555 Oct 6, 2000

Bruce Inscoe wrote:

> I ordered grade 7 (highest precision) stainless steel bearings

> (4)

> for both worms and one 1.250" needle bearing for the RA axis from Les

> at Nordic Bearing in Canada. I got this info from Jimmy Thibert on a

> posting within the group.



Bruce,



It would be interesting to compare the results. I noticed that the

bearings I ordered (also from info on the list) were ABEC-5 grade which is

one step below the ABEC-7. There is a higher grade bearing available

(ABEC-9), but looking at the tolerance specs, I wonder if the difference

would justify the additional cost. I have some PE tracking shots of my

mount that I took last time I was out (about 10 minute unguided with the

Tak FS 102 and ST-7), so I will have something to compare it to after I do

the mod. I also have the Goto retro on order, so I'll be interested in

seeing the difference the servos will make.

What has been interesting to compare is that Tom Carrico (also on this

list) and I have just about identical setups right next to each other out

at ARGO, the main difference being I bought mine back in '97 and his is a

newer model. While our results have been similar, there is some

difference, although we haven't explored this in depth. Something for next

observing season, I think.



--

Jim Girard

www.teleport.com/~argo



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

#556 Oct 6, 2000

I'm confused about this explanation. I've had some problems with

mine as well and Scott gave me the same advice. But I'm still not

clear as to what this means.

> problem over with them. They contacted Scott Losmandy and after

many > phone calls they had me call Scott directly. After describing the

> problem first hand to Scott he finally said "it sounds like you

have > the DSC gear on the RA shaft too tight. You want about two

> thicknesses

> of paper clearence between the gear and the thick washer



I recently had a motor go out on me which in turn took out the

controller as well. I took everything apart to see if I could

ascertain what had happpened.



While I had the mount taken apart, I noticed that the RA telescope

mount

assembly (which fits into the shaft housing with the bearings and

grease),

did not turn easily when all clutches were fully releaseed. It seems

that I

have about 160 degrees of free motion but when I reach that limit, it

binds

severely. I think that perhaps the machined "cutout" that fits over

the

shaft housing is out of round. So, when I set up the scope, I need

to check

to make sure that the free rotation end is up when I mount the scope.

That's

probably why the motor failed. While I could move the scope manually,

it did

not ever move freely. The large moment arm of the scope made it

fairly easy

for me to move, but the motor, right at the gear, did not have that

advantage. So all you Losmandy owners out there, check your RA and

DEC

assemblies before you mount any equipment or counter weights before

you set

up. It might save you the cost of a motor and controller card. ($380

plus

shipping and tax!).



Michelle



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

#559 Oct 6, 2000

Grade 7!!!, man that's a high grade of bearings.. I have used grade 5 in the

past and those are delicate.. one mistake and they develop flat spots.



"Bruce Inscoe" midniterider@...> wrote:

> I ordered grade 7 (highest precision) stainless steel bearings

>(4)

>for both worms and one 1.250" needle bearing for the RA axis from Les

>at Nordic Bearing in Canada. I got this info from Jimmy Thibert on a

>posting within the group.



Herm

Astropics home.att.net/~hermperez



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

#560 Oct 6, 2000

Herm:

Just trying to make my G11 track as accurately as possible.



Bruce



hermperez@w... wrote: > Grade 7!!!, man that's a high grade of bearings.. I have used grade

5 in the > past and those are delicate.. one mistake and they develop flat

spots. >

> "Bruce Inscoe" midniterider@m...> wrote:

>

> > I ordered grade 7 (highest precision) stainless steel bearings

> >(4)

> >for both worms and one 1.250" needle bearing for the RA axis from

Les > >at Nordic Bearing in Canada. I got this info from Jimmy Thibert

on

a > >posting within the group.

>

> Herm

> Astropics home.att.net/~hermperez



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

#561 Oct 6, 2000

Ive reduced the entire engineering of the g-11 mount to viruses as an

analogy.Once level and balanced in all 3 axes:

the following viruses are possible and the remedies are noted:

1)polar alignment off.Symptom...correction in 1 axis moves the other

axis.remedy...15 minute dec drift (not 5)

2)regular ra overcorrections.symptoms:correct in ra for a specific error and

star jumps past or it takes twice as many corrections as suspected.

(if manualy guiding or if using an autoguider and the correction speeds are

correct)

remedy....too much or too little off balance weighting affecting stepper

motors.

3)spurious errors(not reliable and not pec)

remedy...new abek7 r4zz 1/4" bearings on worm

Also use slick 50 or something like it on worm and gear instead of grease

4)dec not orthogonal after clutching/slewing/clutching

remedy..3'rd bearing in dec housing (needle bearingBA-2016)

5)any wobble in ra or anytime using a load of more than 30 pounds.

remedy:3'rd bearing in ra housing (needle bearing BA-2016)

6)all of above completed and still guiding is erratic

remedy:slack off worm to gear pressure in ra (backlash is ok for guiding but

looks ugly for slewing)

7)all of above done but still erratic guiding

remedy:check seeing conditions, scope environment(cords stuck etc.)



Perhaps others can add to this then post for future reference at "files"



jimmy



>From: "Bruce Inscoe" midniterider@...>

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: [Losmandy_users] Re: PERIODIC ERROR PIC

>Date: Fri, 06 Oct 2000 11:23:29 -0000

>

>--- In Losmandy_users@egroups.com, Jim Girard argo@t...> wrote:

> > Bruce Inscoe wrote:

> >

> > > I've contacted Scott and he asked me to ship my worm gear and

> > > bearing blocks to him so that he can check it out. He sent me a

> > > replacement to use, but the error is as bad as the one that I sent

> > > him. I've been actively following the threads on replacing the

> > > worm bearings, as well as adding additional needle bearings in

>the

>RA

> > > and DEC axes and have ordered these (for $110.00)!

> >

> > Bruce,

> >

> > Where did you order your parts from? I just ordered the same (or

>similar)

> > parts from McMaster-Carr and the total was something like $28 +

>shipping.

>

>Jim:

> I ordered grade 7 (highest precision) stainless steel bearings

>(4)

>for both worms and one 1.250" needle bearing for the RA axis from Les

>at Nordic Bearing in Canada. I got this info from Jimmy Thibert on a

>posting within the group.

>

>Regards,

>Bruce Inscoe

>

>

>

>

>To unsubscribe from this group, send an email to:

>Losmandy_users-unsubscribe@egroups.com

>

>

>



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

#564 Oct 7, 2000

Bruce,



I have had the mount out about 5 times since i have bought it. It

could be that I have yet to run into the problems others have but

uncorrected, I see about a +- 15 arcsec that is quite smooth. These

are the shots I got last time (and my first real astrophotography

session)



All images were done with Fuji 800 Superia Extra at f6 using the AP

focal reducer.



M31, 45 minute exposure.

images.honesty.com/imagedata/3/8/8/15262388.jpg



M33, 15 minute exposure (It was too cold to continue!!!)

images.honesty.com/imagedata/3/9/0/15262390.jpg



The Double Cluster. Composite of two 25 minute shots. (Well one was

50 minutes but 25 of these was with the lens cap on the telescope!)

images.honesty.com/imagedata/3/9/1/15262391.jpg



It would still be interesting to try out the mount withsomething

other than a stepper. This would rule out a problem with the

electronics too.



Tom





--- In Losmandy_users@egroups.com, "Bruce Inscoe"

midniterider@m...> wrote: > --- In Losmandy_users@egroups.com, tblahovici@l... wrote:

> > I can't help but notice that the periodic error is not smooth as

> > would be expected if you had gear runout or the worm was not

> > perfectly round. Could it be perhaps the stepper motors that

cause > > this problem? It would be interesting to try to swap the stepper

> > motor with an ac synchronic motor which has I believe the same

> shaft

> > and mounting holes. One of the 1 rpm motors from hurst. If you

> then

> > get smooth periodic error, you have eliminated the stepper as the

> > culprit.

> > On another note, I see many members saying they get 2's and 1's

> > followed by 5's and 7's on their ST4's. I have the same behavior

> > with a 990mm guide scope but all my photos show perfect tracking

> > though my 1000mm main scope (45 minutes shots blown up to 8x10).

Is > > there really an issue here or is this like the "audiophile"

> syndrome

> > where we are always trying to perfect something close to

perfection? > > Regards, Tom Blahovici

>

> Tom:

> I have swapped both motors and worms several times...no

change. > Most users of the G11/ST4 combo, guiding at 1/2 meter focal length,

> report long strings of 0's and 1's with maybe an occasional 2. At

1 > meter, these values would be doubled. If an error of 3 or above

> occurs, it will show up in image. At a one meter focal length,

which > is pretty much what you have, then maybe a 5 is OK. At one meter

on > my G11/ST4, it can't keep the star in the box and I get E's in RA.

> Imaging through an FS128 at prime focus, and guided with the ST4,

out > of twenty, 2-minute exposures, I may get 2 that don't show

elongated > stars. I know that the G11 is capable of far better.

>

> Regards,

> Bruce Inscoe



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

#566 Oct 7, 2000

One of the best experiments that I ever did with an ST-4 is as

follows: In the find and focus mode center a star and then track its

position as a function of time with the motor drive running. What

you get is the arcsec/min drift. This gives you info about how close

t polar alignment you are and most importantly how often a correction

should be made. In my case I thought I had sever sky fluctuation and

set AA to 5. Though the star was moderatly bright it took longer to

correct than it did to loop around 5 times. The ST-4 is an excellent

and variable piece of equipment. Being such it has a lot of controls

to be set. In my case, the fl is about 3 meters and this mmakes

everything more sensitive than a 1 meter scope.





--- In Losmandy_users@egroups.com, "Bruce Inscoe"

midniterider@m...> wrote: > Hi Folks:

> I've posted a .jpg under the "files" section to illustrate why

> I've been asking about bearings, worms, etc. I have a permanent

pier > setup in an observatory and have done some astrophotography but

I've > been unable to get my G-11 to track accurately enough to do

imaging. > My setup consists of an ST4 guiding through a Pronto guidescope

> piggy-backed on a Tak FS128. The ST4/G11 combo has produced

volumes > of quality astrophotos and after researching, I knew that was the

way > to go. Unfortunately, my G-11 can't keep the guidestar in the box

so > the ST4 has large errors.

> I've contacted Scott and he asked me to ship my worm gear and

> bearing blocks to him so that he can check it out. He sent me a

> replacement to use, but the error is as bad as the one that I sent

> him. I've been actively following the threads on replacing the

> worm bearings, as well as adding additional needle bearings in the

RA > and DEC axes and have ordered these (for $110.00)!

> The photo I posted is a 4 minutes exposure taken through a

> Starlight Xpress HX516 with the FS128 at prime focus with the G11

> head

> offset from it's polar alignment to better show the error. I'm

> confident Scott will help resolve the problem and I'm really

looking > forward to doing some imaging with the setup.

>

> Regards,

> Bruce Inscoe







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

#567 Oct 7, 2000

--- In Losmandy_users@egroups.com, tblahovici@l... wrote: > Bruce,

>

> I have had the mount out about 5 times since i have bought it. It

> could be that I have yet to run into the problems others have but

> uncorrected, I see about a +- 15 arcsec that is quite smooth.

These > are the shots I got last time (and my first real astrophotography

> session)

>

> All images were done with Fuji 800 Superia Extra at f6 using the AP

> focal reducer.

>

> M31, 45 minute exposure.

> images.honesty.com/imagedata/3/8/8/15262388.jpg

>

> M33, 15 minute exposure (It was too cold to continue!!!)

> images.honesty.com/imagedata/3/9/0/15262390.jpg

>

> The Double Cluster. Composite of two 25 minute shots. (Well one

was > 50 minutes but 25 of these was with the lens cap on the telescope!)

> images.honesty.com/imagedata/3/9/1/15262391.jpg

>

> It would still be interesting to try out the mount withsomething

> other than a stepper. This would rule out a problem with the

> electronics too.

>

> Tom

>

>

> Tom:

Nice pictures! I sure wish my G11 would do that! With Scott's

support and help, I'm confident that mine will soon.



Bruce Inscoe



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

#573 Oct 8, 2000

>>>In the find and focus mode center a star and then track its

position as a function of time with the motor drive running.<<



How is this done? I have not heard of using the ST4 in this mode.



Thanks, and take care,

Gregory david Stempel

FIREFRAME



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

#575 Oct 8, 2000

Greg:

In the "find and focus" mode for the ST4, it takes an image of a

specified length of time, and displays three sets of two digits, ie:



65 46 75



The first two digits are brightness (1-99), the next two sets are x

and y coordinates of where the star image is falling on the chip.

This display updates at the approximate rate of the exposure time

that

was set. I'm not sure about trying to use this to determine PE,

because with my setup, using 2x guiding speed, I have to press the

buttons on the hand controller for some time to move the star to

roughly center...values of 50 and 50. After pressing the "guide"

button, I get errors in both "+" and "-" directions quite quickly. I

think that the ST4 goes into some sort of sub-pixel mode that it

doesn't use while only in "find and focus", but I'm probably wrong.

If I can put it into summary: While in "find and focus" the x and y

readouts remain constant until I move it manually with the hand

controller. (By the posted recommendation, I have no PE judging by

this). However, my G11/ST4 combination in "guide" mode, can't keep

the guidestar in the box and I get "E's" in RA. You can also look at

the .jpg that I posted under "files" section and see that I have gobs

of PE.



Regards,

Bruce Inscoe







Gregory David Stempel

fyrframe@c...> wrote: > >>>>In the find and focus mode center a star and then track its

> position as a function of time with the motor drive running.<<

>

> How is this done? I have not heard of using the ST4 in this mode.

>

> Thanks, and take care,

> Gregory david Stempel

> FIREFRAME



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

#599 Oct 10, 2000

Bruce, the Pronto may not be enough focal length to guide with an st4...I have

been having "flexure problems" for a long time, but recently I discovered that

it was just that the Orion 80mm STR (400mm focal length) did not have enough

magnification...last week I tried a 2x barlow and it tracked perfectly without

"flexure"...I figured this out after Paul Sterngold posted a hint in this mail

list.. Thanks Paul..



so before you go completely crazy try a barlow in your guidescope, I know

everybody has a barlow in their kit so give it a try.



BTW, I just ordered a longer focal length guidescope and will be getting rid of

the Lumicon offaxis guider..



"Bruce Inscoe" midniterider@...> wrote:

> I have a permanent pier

>setup in an observatory and have done some astrophotography but I've

>been unable to get my G-11 to track accurately enough to do imaging.

>My setup consists of an ST4 guiding through a Pronto guidescope

>piggy-backed on a Tak FS128.

Herm

Astropics home.att.net/~hermperez



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

#600 Oct 10, 2000

Herm:

When I use a Barlow and extend the guiding focal length to about

one meter, the ST4 can't keep the star in the box. With the Pronto

at

prime focus (about 1/2 meter), I get errors up to 4 and 5. When this

is doubled, it's "out of the box".



Regards,

Bruce Inscoe





, hermperez@w... wrote: > Bruce, the Pronto may not be enough focal length to guide with an

st4...I have > been having "flexure problems" for a long time, but recently I

discovered that > it was just that the Orion 80mm STR (400mm focal length) did not

have enough > magnification...last week I tried a 2x barlow and it tracked

perfectly without > "flexure"...I figured this out after Paul Sterngold posted a hint

in

this mail > list.. Thanks Paul..

>

> so before you go completely crazy try a barlow in your guidescope,

I

know > everybody has a barlow in their kit so give it a try.

>

> BTW, I just ordered a longer focal length guidescope and will be

getting rid of > the Lumicon offaxis guider..

>

> "Bruce Inscoe" midniterider@m...> wrote:

>

> > I have a permanent pier

> >setup in an observatory and have done some astrophotography but

I've > >been unable to get my G-11 to track accurately enough to do

imaging. > >My setup consists of an ST4 guiding through a Pronto guidescope

> >piggy-backed on a Tak FS128.

> Herm

> Astropics home.att.net/~hermperez







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

#601 Oct 10, 2000

never mind, you definitely have problems..



Herm



"Bruce Inscoe" midniterider@...> wrote:

>Herm:

> When I use a Barlow and extend the guiding focal length to about

>one meter, the ST4 can't keep the star in the box. With the Pronto

>at

>prime focus (about 1/2 meter), I get errors up to 4 and 5. When this

>is doubled, it's "out of the box".

>

>Regards,

>Bruce Inscoe

>

>

>, hermperez@w... wrote:

>> Bruce, the Pronto may not be enough focal length to guide with an

>st4...I have

>> been having "flexure problems" for a long time, but recently I

>discovered that

>> it was just that the Orion 80mm STR (400mm focal length) did not

>have enough

>> magnification...last week I tried a 2x barlow and it tracked

>perfectly without

>> "flexure"...I figured this out after Paul Sterngold posted a hint

>in

>this mail

>> list.. Thanks Paul..

>>

>> so before you go completely crazy try a barlow in your guidescope,

>I

>know

>> everybody has a barlow in their kit so give it a try.

>>

>> BTW, I just ordered a longer focal length guidescope and will be

>getting rid of

>> the Lumicon offaxis guider..

>>

>> "Bruce Inscoe" midniterider@m...> wrote:

>>

>> > I have a permanent pier

>> >setup in an observatory and have done some astrophotography but

>I've

>> >been unable to get my G-11 to track accurately enough to do

>imaging.

>> >My setup consists of an ST4 guiding through a Pronto guidescope

>> >piggy-backed on a Tak FS128.

>> Herm

>> Astropics home.att.net/~hermperez

>

>

>

>To unsubscribe from this group, send an email to:

>Losmandy_users-unsubscribe@egroups.com

>

>



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