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Anyone plate-solve through an OAG?

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#1 Gobo333

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Posted 25 October 2020 - 10:55 PM

Curious if anyone has tried to plate-solve through an OAG using their guide camera?

 

I havent tried myself, but I plan on it.  Looking for thoughts, info, tips, suggestions etc.

 

Thanks!



#2 AZ Maverick

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Posted 25 October 2020 - 11:03 PM

While PHD2 finds the centroid on the stars in my OAG at 952mm FL, the stars are pretty smeared and I don't think they would plate solve - but then I have never tried either...

But then out of curiosity - why do you want to plate solve a guide camera image???



#3 Gobo333

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Posted 26 October 2020 - 12:15 AM

While PHD2 finds the centroid on the stars in my OAG at 952mm FL, the stars are pretty smeared and I don't think they would plate solve - but then I have never tried either...

But then out of curiosity - why do you want to plate solve a guide camera image???

I am experimenting with using my ASIair to control my mount for visual go to, making star alignment unnecessary and polar alignment easy.  It works so far. See thread below. 
 

https://www.cloudyni...sual-astronomy/

 

So, I figured if I can do the same thing with an OAG, I only need one main scope, but maybe a lot of other issues.  I am considering a flip mirror or ONAG too, but the inexpensive OAG and guide camera giving a visual rig plate solve capability is a sweet idea in a small package. 
 

I’ll mock it up and try it myself soon. I’m testing plate solving using an old ASIair, ASI120MM, and a WO 50mm guidescope next.  Trying to get it working as cheap as possible. 



#4 rgsalinger

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Posted 26 October 2020 - 12:16 AM

It's unlikely because the FOV is small and because there are few stars. You might get it to work occasionally under optimal conditions. The only reason I know of to do that is to determine exactly how the FOV of the main camera and the guide camera relate to each other. 



#5 bobzeq25

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Posted 26 October 2020 - 01:03 AM

I am experimenting with using my ASIair to control my mount for visual go to, making star alignment unnecessary and polar alignment easy.  It works so far. See thread below. 
 

https://www.cloudyni...sual-astronomy/

 

So, I figured if I can do the same thing with an OAG, I only need one main scope, but maybe a lot of other issues.  I am considering a flip mirror or ONAG too, but the inexpensive OAG and guide camera giving a visual rig plate solve capability is a sweet idea in a small package. 
 

I’ll mock it up and try it myself soon. I’m testing plate solving using an old ASIair, ASI120MM, and a WO 50mm guidescope next.  Trying to get it working as cheap as possible. 

You'd do better with a guidescope than an OAG.  Widefield, more data for the platesolving program.  You would have to align it to the main scope, but with the usual mounting rings, that's not hard.



#6 alphatripleplus

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Posted 26 October 2020 - 07:37 AM

It the star shapes are distorted in the OAG, that may also not help the platesolve. I agree it would be easier to platesolve through a well-aligned guidescope if you have one.



#7 Gobo333

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Posted 26 October 2020 - 12:49 PM

It's unlikely because the FOV is small and because there are few stars. You might get it to work occasionally under optimal conditions. The only reason I know of to do that is to determine exactly how the FOV of the main camera and the guide camera relate to each other. 

 

 

You'd do better with a guidescope than an OAG.  Widefield, more data for the platesolving program.  You would have to align it to the main scope, but with the usual mounting rings, that's not hard.

 

 

It the star shapes are distorted in the OAG, that may also not help the platesolve. I agree it would be easier to platesolve through a well-aligned guidescope if you have one.

 

I've done this with a guide scope and it works very well.  

 

I was just thinking a device that slips into the main-scope's light path in front of an eyepiece might be a slick solution and eliminate with the need for a separate scope and the alignment of the two scopes.  

 

I'm beginning to think an ONAG or a flip mirror is the better solution to eliminate the need for scope alignment.

 

Thx for the replies.  I appreciate it.



#8 descott12

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Posted 26 October 2020 - 12:51 PM

I use my guidescope as a plate solver/e-finder all the time. But it is an external guide scope, not an OAG. I switch between platesolving and phd2 as needed. Works quite nicely.



#9 Bob Denny

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Posted 26 October 2020 - 12:58 PM

To follow up on @rgsalinger's post above, consider the field of view on your OAG. Any plate solver must match a star pattern against a star catalog to find the same pattern. So many stars (in the entire sky) so many "close matches" when only a few stars are showing, and consider that the guide camera could be mounted at any arbitrary angle with respect to the equatorial coordinate system (the position angle). Imagine trying to plate solve an OAG with only 2 visible stars in it. Impossible.


Edited by Bob Denny, 26 October 2020 - 12:59 PM.


#10 bobzeq25

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Posted 26 October 2020 - 01:03 PM

I've done this with a guide scope and it works very well.  

 

I was just thinking a device that slips into the main-scope's light path in front of an eyepiece might be a slick solution and eliminate with the need for a separate scope and the alignment of the two scopes.  

 

I'm beginning to think an ONAG or a flip mirror is the better solution to eliminate the need for scope alignment.

 

Thx for the replies.  I appreciate it.

It might be a slick solution, but it's not better.  It's complicated and a potential headache.  The separate guidescope is cheap, easy, and will work reliably.  Alignment borders on trivial.  Get a bright star in the field of the main scope, and adjust the guidescope.

 

Why make life hard when it can be easy?
 



#11 rgsalinger

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Posted 26 October 2020 - 03:30 PM

I think that you're confusing a few things. You do not have to plate solve an OAG image to get good guiding. It's not like using a guidescope where you need the two scopes well aligned, at all. The mirror or prism in the OAG means that the two cameras and the scope are all orthogonal to each other. So, all you do is to calibrate and you're good for the night. That's one of the advantages of an OAG. There's no alignment step. 

Rgrds-Ross



#12 Gobo333

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Posted 26 October 2020 - 10:54 PM

It might be a slick solution, but it's not better.  It's complicated and a potential headache.  The separate guidescope is cheap, easy, and will work reliably.  Alignment borders on trivial.  Get a bright star in the field of the main scope, and adjust the guidescope.

 

Why make life hard when it can be easy?
 

Its easy for you and I, but I’m a product designer and I’m thinking it would make a good product, so I’m rooting around for ideas. The thought of a single accessory all inclusive and drop in is appealing. 

 

I think that you're confusing a few things. You do not have to plate solve an OAG image to get good guiding. It's not like using a guidescope where you need the two scopes well aligned, at all. The mirror or prism in the OAG means that the two cameras and the scope are all orthogonal to each other. So, all you do is to calibrate and you're good for the night. That's one of the advantages of an OAG. There's no alignment step. 

Rgrds-Ross

Not confused but thank you regardless. I use OAGs for guiding and love them. Once set they are great.  What I am digging for here is not for AP, but as a plate solving system for VISUAL Goto.  I have a nexus push to, and I use ASIair for my photos, and plate solving is SO much easier than’ star alignment that I had to try it with visual. Worked great with a separate scope, and I was just looking to get rid of the second scope. 
 

Loving the input. Thanks everyone.



#13 rgsalinger

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Posted 26 October 2020 - 11:41 PM

Well, you could buy a flip mirror (if they still make them) and with the right adaptor you'd be able to use a large enough camera to be able to plate solve. 

Rgrds-Ross


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#14 TelescopeGreg

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Posted 27 October 2020 - 10:30 PM

If it helps, I have plate solved using my guide scope and its camera.  ZWO 60mm f/4.6 and ASI174MM Mini.  Plenty of field of view and good sensitivity for lots of stars.  By carefully aligning the guide and imaging scopes, I would center an object exactly in the imaging camera.

 

I needed to do this because the imaging camera (an older DSLR) wasn't supported by the computer interface.  It would work just the same with an eyepiece.



#15 Gobo333

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Posted 28 October 2020 - 04:00 PM

Occam’s razor, and the good sensibility found around here, all point to the simplicity of a guide scope.   After sketching out a handful of ideas and iterations, I think that may be the case.  Separating it from focusing duties eliminates a lot of complexity.  I will work on minimizing and compacting it as much as possible for the next mockup.


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#16 Gobo333

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Posted 29 October 2020 - 12:15 AM

Thought I’d share the mock-up with you. Works great. Fastest plate solve ever. 
 

 

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