AP1100 autoguiding


christopheciel
 

Dear all,


My name is Christophe, from France.

This is my first message here.

My english is not very good, as you will see ; I hope you will understand what I mean.


This forum is a great idea.


**


I bought a used 1100 GTO a few months ago from a very nice person, who had it in a small observatory.

This precedent owner had a CP3, then he bought a CP4. He never actualized the PEM, so there is none, using only the mount with a PC and an autoguiding camera to image.


After a couple of weeks of use, I still have some issue with the pointing and tracking. I use only the keypad. The pointing is usually 15-20 arcmin off, on any target in the sky, and, last night, I tried to image M101, and saw that the derive is something like 30" per hour on such a target. The max exposure time I could do was 60sec at 1900 mm focal length.


I calibrated the RAPAS as indicated in the rapas notice, and the mount is leveled as perfectly as I could.


Well, I'm now looking for an autoguiding camera in order to enhance the tracking.


I have a old LACERTA MGEN stand alone autoguiding camera.


https://en.lacerta-optics.com/MGEN_Lacerta-MGEN-II-Superguider-Autoguider-Camera-with


The out plug of this system is an ST4 or RJ12 male plug. I understand that the autoguiding female plug on the CP4 is a RJ11-6 plug.


Are the RJ11-6 and RJ12 plugs compatible ?


So had some of you ever used a same lacerta mgen system on a 1100 GTO ? Do you think this is possible ?


Or should I avoid to use this camera and buy another on ? I have a limited budget right now, alas.


Thank you so much for any help or advice.


Christophe



OlivDeso
 

Hello Christophe

The pointing is usually 15-20 arcmin off, on any target in the sky, and, last night, I tried to image M101, and saw that the derive is something like 30" per hour on such a target. The max exposure time I could do was 60sec at 1900 mm focal length.


by "dérive" which is the French word, do you mean drift I guess, so you get trailling stars.

Do you know I which direction? RA? DEC? or both?

Drift along DEC -> polar align is not good enough  -> perform a very acurate drift aligment using pempro, then fine tune the rapas
Drift along RA axis -> PE -> perform gear remeshing, then PE measurement with pempro and then upload PEC from pempro to the mount


There are 2 things to do to improve the PE :

1) gear re-meshing : first of all, before any PE measurement, it is very important to have a proper gear meshing, especially if the mount has travelled and/or was used at a different temperature.

-> follow the AP procedure here, it isvery simple and very efficient.




On to of that, I 'd like to mention a trick : on the forst AP1100, I found the CP3 motor spring loader to be a little bit to strong. It fact it comes from the screw which secure the spring : the thread is a little bit too short compared to the spring length. Not a big deal for DEC, but significant for RA.

My advise : on these older AP1100, while tuning the RA mesh, unscrew the spring holding screew by 2 turns, not more. and follow the AP procedure.
It will ensure applying just the needed pressure to get the best meshing and lowest EP.
Once this gear meshing is done, you can 

2) Once gear mesh has been properly set, you can run pempro and measure the PE.
- first polar align precisely enough, using the drift alingment tool
- measure the PE between +1° and +5° after the meridian, not more. "rewind" if needed



Are the RJ11-6 and RJ12 plugs compatible ? -> yes, in fact RJ11 is the 4 contacts version of the RJ12 

(RJ11 6 positions 4 contact (6p4c) and RJ12 6p6c. So RJ11-6 is a wrong naming, the right naming is RJ12 for 6p6c RJ plug)

Now since you have the CP4 ou CP3, you could also use the pulse guiding whicjh is a little bit more acurate than the ST4 : the mount itself manages the pulse duration. Thought in this particular case, the difference is likely to be marginal with the Lacerta Mgen. (it could be more signigficant with an old PC)


clear skies

Oliv Deso

Le lundi 2 mai 2022, 05:26:56 UTC+2, christopheciel via groups.io <christopheciel@...> a écrit :


Dear all,


My name is Christophe, from France.

This is my first message here.

My english is not very good, as you will see ; I hope you will understand what I mean.


This forum is a great idea.


**


I bought a used 1100 GTO a few months ago from a very nice person, who had it in a small observatory.

This precedent owner had a CP3, then he bought a CP4. He never actualized the PEM, so there is none, using only the mount with a PC and an autoguiding camera to image.


After a couple of weeks of use, I still have some issue with the pointing and tracking. I use only the keypad. The pointing is usually 15-20 arcmin off, on any target in the sky, and, last night, I tried to image M101, and saw that the derive is something like 30" per hour on such a target. The max exposure time I could do was 60sec at 1900 mm focal length.


I calibrated the RAPAS as indicated in the rapas notice, and the mount is leveled as perfectly as I could.


Well, I'm now looking for an autoguiding camera in order to enhance the tracking.


I have a old LACERTA MGEN stand alone autoguiding camera.


https://en.lacerta-optics.com/MGEN_Lacerta-MGEN-II-Superguider-Autoguider-Camera-with


The out plug of this system is an ST4 or RJ12 male plug. I understand that the autoguiding female plug on the CP4 is a RJ11-6 plug.


Are the RJ11-6 and RJ12 plugs compatible ?


So had some of you ever used a same lacerta mgen system on a 1100 GTO ? Do you think this is possible ?


Or should I avoid to use this camera and buy another on ? I have a limited budget right now, alas.


Thank you so much for any help or advice.


Christophe



OlivDeso
 

p.s. pointing and drift are 2 different subjets

- drift along DEC is related to polar alignment (so a pure mecanical topic)
- pointing is related to the calibration of the pointing model. (mainly a software synchronisation subject)


Le lundi 2 mai 2022, 19:00:37 UTC+2, OlivDeso <olivdeso@...> a écrit :


Hello Christophe

The pointing is usually 15-20 arcmin off, on any target in the sky, and, last night, I tried to image M101, and saw that the derive is something like 30" per hour on such a target. The max exposure time I could do was 60sec at 1900 mm focal length.


by "dérive" which is the French word, do you mean drift I guess, so you get trailling stars.

Do you know I which direction? RA? DEC? or both?

Drift along DEC -> polar align is not good enough  -> perform a very acurate drift aligment using pempro, then fine tune the rapas
Drift along RA axis -> PE -> perform gear remeshing, then PE measurement with pempro and then upload PEC from pempro to the mount


There are 2 things to do to improve the PE :

1) gear re-meshing : first of all, before any PE measurement, it is very important to have a proper gear meshing, especially if the mount has travelled and/or was used at a different temperature.

-> follow the AP procedure here, it isvery simple and very efficient.




On to of that, I 'd like to mention a trick : on the forst AP1100, I found the CP3 motor spring loader to be a little bit to strong. It fact it comes from the screw which secure the spring : the thread is a little bit too short compared to the spring length. Not a big deal for DEC, but significant for RA.

My advise : on these older AP1100, while tuning the RA mesh, unscrew the spring holding screew by 2 turns, not more. and follow the AP procedure.
It will ensure applying just the needed pressure to get the best meshing and lowest EP.
Once this gear meshing is done, you can 

2) Once gear mesh has been properly set, you can run pempro and measure the PE.
- first polar align precisely enough, using the drift alingment tool
- measure the PE between +1° and +5° after the meridian, not more. "rewind" if needed



Are the RJ11-6 and RJ12 plugs compatible ? -> yes, in fact RJ11 is the 4 contacts version of the RJ12 

(RJ11 6 positions 4 contact (6p4c) and RJ12 6p6c. So RJ11-6 is a wrong naming, the right naming is RJ12 for 6p6c RJ plug)

Now since you have the CP4 ou CP3, you could also use the pulse guiding whicjh is a little bit more acurate than the ST4 : the mount itself manages the pulse duration. Thought in this particular case, the difference is likely to be marginal with the Lacerta Mgen. (it could be more signigficant with an old PC)


clear skies

Oliv Deso
Le lundi 2 mai 2022, 05:26:56 UTC+2, christopheciel via groups.io <christopheciel@...> a écrit :


Dear all,


My name is Christophe, from France.

This is my first message here.

My english is not very good, as you will see ; I hope you will understand what I mean.


This forum is a great idea.


**


I bought a used 1100 GTO a few months ago from a very nice person, who had it in a small observatory.

This precedent owner had a CP3, then he bought a CP4. He never actualized the PEM, so there is none, using only the mount with a PC and an autoguiding camera to image.


After a couple of weeks of use, I still have some issue with the pointing and tracking. I use only the keypad. The pointing is usually 15-20 arcmin off, on any target in the sky, and, last night, I tried to image M101, and saw that the derive is something like 30" per hour on such a target. The max exposure time I could do was 60sec at 1900 mm focal length.


I calibrated the RAPAS as indicated in the rapas notice, and the mount is leveled as perfectly as I could.


Well, I'm now looking for an autoguiding camera in order to enhance the tracking.


I have a old LACERTA MGEN stand alone autoguiding camera.


https://en.lacerta-optics.com/MGEN_Lacerta-MGEN-II-Superguider-Autoguider-Camera-with


The out plug of this system is an ST4 or RJ12 male plug. I understand that the autoguiding female plug on the CP4 is a RJ11-6 plug.


Are the RJ11-6 and RJ12 plugs compatible ?


So had some of you ever used a same lacerta mgen system on a 1100 GTO ? Do you think this is possible ?


Or should I avoid to use this camera and buy another on ? I have a limited budget right now, alas.


Thank you so much for any help or advice.


Christophe



Howard Hedlund
 

Hi Christophe,

Congratulations on acquiring the 1100GTO.  You will love it!

Pointing errors can have several sources:
  • The most common cause of pointing errors is polar misalignment.
  • If the RAPAS was not properly calibrated, it may not give good results.  If it was calibrated incorrectly, it will certainly fail to give good pointing.
  • Orthogonality affects pointing, especially nearer to the pole.  Orthogonality problems show themselves most strongly after a meridian flip.
  • Pointing problems are almost never the fault of the mount.
As Oliv points out, one of the first things to determine is whether your drift is in RA, Dec or in both axes.  You can easily determine which direction on the chip is RA by stopping tracking for a short while in the middle of an image.  The streak that results will be in the direction of RA.

You will need to either create a good PE curve or autoguide.  If you received the copy of PEMPro that came with the mount, you can both cure the periodic error and fix the polar alignment at the same time.

You may or may not need to remesh the gears.  This can be quite easily tested using the instructions in our website's technical support section.  https://astro-physics.info/tech_support/mounts/gear-mesh-1600-1100-mach1-2014-10-24.pdf 

Contact me at Astro-Physics for further assistance.

Howard


christopheciel
 

Dear all,


Thanks for the very accurate and informative replies.


Indeed, « derive » was not the correct word, Oliv, You're right. I meant drift, of course. So sorry.


Unfortunately, I only own a Canon 650 DSLR, right now, and I'm almost sure that I cannot use it with Pempro or even perform a polar alignment with such a software like phd2 guiding. The astronomical camera will come more later, next winter.


I think the primary drift defect, is in dec, and comes from a bad polar alignment, causing also some imperfections when using the goto.


Gear re-meshing is a good idea. I will try it asap. I suspect that the precedent owner of this mount possibly never did it. I asked him yeasterday, but I'm waiting for his answer. He possibly rely on the only autoguiding/APCC to correct all the drift defects, and was successful, as his really good images prove it. Beside being a nice person, he is also a keen and competent astrophotographer.


Anyway, I will also check upon the orthogonality, and try to get a precise measurement of the drift, both in RA and dec. Actually, my scope is a C11edge, and it is set up on a 16'' losmandy dovetail saddle, such a system most probably being well orthogonal.


Will try the Lacerta Mgen, and, if not working properly, order a small autoguiding camera such as a zwo asi 120 or 290 mini.


Once more, many thanks for the help and advices. I will come back later, as soon as weather permits to perform some tests on the sky.


Oliv, I will contact you via Astrosurf or WA soon, if you like.


Cheers,

Christophe



Le mardi 3 mai 2022, 03:44:24 UTC+2, Howard Hedlund <howard@...> a écrit :


Hi Christophe,

Congratulations on acquiring the 1100GTO.  You will love it!

Pointing errors can have several sources:
  • The most common cause of pointing errors is polar misalignment.
  • If the RAPAS was not properly calibrated, it may not give good results.  If it was calibrated incorrectly, it will certainly fail to give good pointing.
  • Orthogonality affects pointing, especially nearer to the pole.  Orthogonality problems show themselves most strongly after a meridian flip.
  • Pointing problems are almost never the fault of the mount.
As Oliv points out, one of the first things to determine is whether your drift is in RA, Dec or in both axes.  You can easily determine which direction on the chip is RA by stopping tracking for a short while in the middle of an image.  The streak that results will be in the direction of RA.

You will need to either create a good PE curve or autoguide.  If you received the copy of PEMPro that came with the mount, you can both cure the periodic error and fix the polar alignment at the same time.

You may or may not need to remesh the gears.  This can be quite easily tested using the instructions in our website's technical support section.  https://astro-physics.info/tech_support/mounts/gear-mesh-1600-1100-mach1-2014-10-24.pdf 

Contact me at Astro-Physics for further assistance.

Howard


Mike Dodd
 

On 5/4/2022 9:03 AM, christopheciel via groups.io wrote:

Unfortunately, I only own a Canon 650 DSLR, right now,[...] The astronomical camera will come more later, next winter.
Will try the Lacerta Mgen, and, if not working properly, order a small autoguiding camera such as a zwo asi 120 or 290 mini.
I use an ASI120 as a guide camera, but it also can be a "main" camera on a telescope. It has a small FOV, but plenty large enough to get you started.

You can use a '120 or '290 with PEMPro to do a polar alignment and to create a PE curve. Just attach the camera to your main telescope, then tell PEMPro it is your imaging camera. You will need to download and install the ZWO ASCOM driver so PEMPro can connect to your camera.

--- Mike
http://astronomy.mdodd.com


christopheciel
 

Thanks Mike.
I will probably do that. It seems easy, and that's what I need !
C.


Howard Hedlund
 

Those little ZWO guide cameras are really neat!  Either one would be a perfect utility camera.   It would be simple to use it for all PEMPro functions.  One would also be perfect with our VarioFinder to start guiding while imaging with your DSLR. 
https://www.astro-physics.com/1060vgkit 
 My colleague George uses a similar camera with the VarioFinder with great results.


Steven Panish
 

Christophe-
To check ( and correct) orthogonality, download the ConeSharp program.  Easy to use and accurate.
I use an ASI290 as a guide camera, works very well.
Steve

On Thu, May 5, 2022 at 9:21 PM Howard Hedlund <howard@...> wrote:
Those little ZWO guide cameras are really neat!  Either one would be a perfect utility camera.   It would be simple to use it for all PEMPro functions.  One would also be perfect with our VarioFinder to start guiding while imaging with your DSLR. 
https://www.astro-physics.com/1060vgkit 
 My colleague George uses a similar camera with the VarioFinder with great results.



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Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.


Greg Vaughn
 

Steve,

 

Thanks for the advice about ConeSharp – I was unfamiliar with it.  I looked up the instructions and it seems pretty straightforward.

 

However, I am curious how you are supposed to adjust out the error and bring the alignment star back in the center of view.   It says to only use the adjustment bolts at the front and the back of the dovetail.  Here is the quotation: ”Remember that you are only allowed to make corrections using the alignment adjusting bolts at the front/back of the dovetail.”

 

I am using a 130EDFGT on a Mach2 on which I’m using an AP DOVEDV10 saddle plate.  The 130 is using the rings  that I purchased with it and they are mounted on an SBD12 12in plate.  The screws for the rings fit in countersunk holes in the plate and have no adjustment.   So I’m at a loss to find the adjusting bolts.   (The Google hit from Cloudy Nights on the topic of ConeSharp proclaims “NO SHIMS.”)

 

Any insight about how you do this would be appreciated.

 

Cheers,

Greg


Virus-free. www.avast.com


Steven Panish
 

Hi Greg,
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings.  Vixen does it for some  premium refractors.  Generally you are going to have to drill and tap holes for the screws...somewhere.  Maybe in the rings.  You need them front and rear, and left and right.   And you may have to use shims where nothing else will work.    I use shims made from aluminum flashing against the tube of my FSQ106.  It's crude but works.  On SCTs I've put adjustment screws in the dovetail attached to the tube (actually the dovetail bar is attached to the rear cell casting and a similar casting in the front).  

However you do it, the program will help.  With AP components you likely won't be too far out.

Steve

On Sun, May 15, 2022 at 3:56 PM Greg Vaughn <gregvaughn@...> wrote:

Steve,

 

Thanks for the advice about ConeSharp – I was unfamiliar with it.  I looked up the instructions and it seems pretty straightforward.

 

However, I am curious how you are supposed to adjust out the error and bring the alignment star back in the center of view.   It says to only use the adjustment bolts at the front and the back of the dovetail.  Here is the quotation: ”Remember that you are only allowed to make corrections using the alignment adjusting bolts at the front/back of the dovetail.”

 

I am using a 130EDFGT on a Mach2 on which I’m using an AP DOVEDV10 saddle plate.  The 130 is using the rings  that I purchased with it and they are mounted on an SBD12 12in plate.  The screws for the rings fit in countersunk holes in the plate and have no adjustment.   So I’m at a loss to find the adjusting bolts.   (The Google hit from Cloudy Nights on the topic of ConeSharp proclaims “NO SHIMS.”)

 

Any insight about how you do this would be appreciated.

 

Cheers,

Greg


Virus-free. www.avast.com



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Greg Vaughn
 

Steve,

 

Thanks for the follow-up on the ConeSharp adjustment method(s).   I just thought I was blindly missing the features that dove plates were supposed to have or could be adjusted to have.

 

Cheers,

Greg

 


Virus-free. www.avast.com


Andrew J
 

On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J


Christopher Erickson
 

Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J


Steven Panish
 

Chris's points are good.  I'm hoping the RC arriving shortly will be stable. 
Steve

On Wed, May 18, 2022 at 1:32 PM Christopher Erickson <christopher.k.erickson@...> wrote:
Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J



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PLEASE NOTE MY NEW EMAIL ADDRESS!!!
Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.


Christopher Erickson
 

When adjusting cone error on OTA's, I often make thin shims from the sides of aluminum pop cans. They are easily cut with scissors and paper punches. And don't stack too many shims together or you might end up with a slightly compressible spacer that will introduce some additional flexure.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Thu, May 19, 2022, 8:06 AM Steven Panish <scpanish1@...> wrote:
Chris's points are good.  I'm hoping the RC arriving shortly will be stable. 
Steve

On Wed, May 18, 2022 at 1:32 PM Christopher Erickson <christopher.k.erickson@...> wrote:
Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J



--
PLEASE NOTE MY NEW EMAIL ADDRESS!!!
Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.


Kent Kirkley
 

Steven
I hope the "RC" is one of the great ones; ie. An RCOS which were/are incredibly stable.
RCOS' motto was "Focus and forget it", as well a no optical flexure issues.
If a Chinese RC, you probably won't experience this.
Kent Kirkley



-----Original Message-----
From: Steven Panish <scpanish1@...>
To: main@ap-gto.groups.io
Sent: Thu, May 19, 2022 1:06 pm
Subject: Re: [ap-gto] AP1100 autoguiding

Chris's points are good.  I'm hoping the RC arriving shortly will be stable. 
Steve

On Wed, May 18, 2022 at 1:32 PM Christopher Erickson <christopher.k.erickson@...> wrote:
Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J


--
PLEASE NOTE MY NEW EMAIL ADDRESS!!!
Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.


Christopher Erickson
 

Just for general FYI, RCOS OTA's have terrible secondary mirror-based focusers that are notorious for going berserk and slamming into one extreme of the focus range and then jamming. Best fix is adding a Moonlight Crayford and stop using the secondary-based focus mechanism.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Thu, May 19, 2022, 8:29 AM Kent Kirkley via groups.io <kgkirkley=aol.com@groups.io> wrote:
Steven
I hope the "RC" is one of the great ones; ie. An RCOS which were/are incredibly stable.
RCOS' motto was "Focus and forget it", as well a no optical flexure issues.
If a Chinese RC, you probably won't experience this.
Kent Kirkley



-----Original Message-----
From: Steven Panish <scpanish1@...>
To: main@ap-gto.groups.io
Sent: Thu, May 19, 2022 1:06 pm
Subject: Re: [ap-gto] AP1100 autoguiding

Chris's points are good.  I'm hoping the RC arriving shortly will be stable. 
Steve

On Wed, May 18, 2022 at 1:32 PM Christopher Erickson <christopher.k.erickson@...> wrote:
Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J


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Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.


Steven Panish
 

Unfortunately no, it's a cheap one, a GSO.   RCOS are available in 10", and If I like the cheap one I may go for the RCOS.  My dome is too small for anything larger.   Bad mistake.
Steve

On Thu, May 19, 2022 at 2:29 PM Kent Kirkley via groups.io <kgkirkley=aol.com@groups.io> wrote:
Steven
I hope the "RC" is one of the great ones; ie. An RCOS which were/are incredibly stable.
RCOS' motto was "Focus and forget it", as well a no optical flexure issues.
If a Chinese RC, you probably won't experience this.
Kent Kirkley



-----Original Message-----
From: Steven Panish <scpanish1@...>
To: main@ap-gto.groups.io
Sent: Thu, May 19, 2022 1:06 pm
Subject: Re: [ap-gto] AP1100 autoguiding

Chris's points are good.  I'm hoping the RC arriving shortly will be stable. 
Steve

On Wed, May 18, 2022 at 1:32 PM Christopher Erickson <christopher.k.erickson@...> wrote:
Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J


--
PLEASE NOTE MY NEW EMAIL ADDRESS!!!
Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.



--
PLEASE NOTE MY NEW EMAIL ADDRESS!!!
Due to Google eliminating cheap domain serving, Virginia and I are changing to regular gmail addresses.  The old panishnet address will forward to this address for a short while, but please add the new address, scpanish1@..., to your contact list.


Emilio J. Robau, P.E.
 

I am very critical of much of the Chinese manufactured astro-photography goods, especially the ZWO cameras.   

However, I have to say that my 12" Truss GSO RC is my favorite poor man's telescope.  I had to extend the baffle to eliminate some stray light.   I have an APH-H chip on it and it really rocks.   I use a SI focuser and an AP27TVPH to get it down to about F6.7 or so and I really enjoy that scope.   I also have a Tak collimation scope and can get that thing very well collimated very quickly and it holds collimation in my observatory forever.   I have taken it completely apart to replace the fans and put it back together again and with about 30 to 45 minutes of collimation time, am back in business.  I am going to guess that my mirrors are pretty good at least to my untrained eye.   Pixel peepers may find faults with the field, but I am very happy with it.

I have my real money saved up for AP stuff, and the RC will be the last item to be replaced for a high end unit one day.  However for now and the past six years I do consider my GSO 12" RC with the baffle mod and a SI focuser as the best value scope I own.  I would purchase one again without hesitation.