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OAG Advice

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#1 Cdnpilot

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Posted 07 July 2020 - 10:11 AM

I continue to have problems with good guiding data and oblong stars - especially when overhead. I have a Meade LX200GPS permanently mounted (if that matters) and a Meade DSI camera for guiding. Currently I have an Orion ST-80 as my guide scope.

 

Can someone recommend an OAG that works that they are using? Second question, and this may be in the neighborhood of dumb, but how do you focus the camera?

 

Any help or pointing me in a direction would be appreciated!



#2 rgsalinger

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Posted 07 July 2020 - 10:45 AM

They all "work". I'd get one with a helical focuser which makes life easy. Check also the size of the prism - that will determine the field of view. Then it's up to your budget!

 

Basically you need to place the guide camera chip at the same distance from the back of the scope as the main camera chip. Some people spend time carefully measuring that distance with calipers. I just have so many spacers around after using OAG's for 10 years that I trust I can find one if I need it. So I just eyeball it to get a quick starting point. NB -- It does get more complicated when using a focal reducer or flattener because now you not only need the two cameras to be par focal, but they also have to be an exact distance from the back of the reducer or flattener..

 

What I recommend is that people use the moon to get started - it's easy to find it in the guide camera (just slew to it and follow the light) and then you can see what you are doing. When the terminator is sharp you're close enough to go to stars instead. Otherwise, it's really just trial and error. Either you are too far in or too far out. What I do is start with the camera pushed all the way into the OAG. I  then back it out in small increments using fairly high gain and use at least 5 second exposures. Once it focuses I lock it down. If it never focuses then I almost certainly know that I need more spacing for the MAIN camera. I usually prove this by moving the focuser in until the guide camera does come into focus.  

 

Rgrds-Ross



#3 scadvice

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Posted 07 July 2020 - 11:15 AM

Here are two post and threads on the subject.

 

This one post #4

 

https://www.cloudyni...be-please-help/

 

And on this one post #4 also:

 

https://www.cloudyni...s-guide-camera/


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#4 Cdnpilot

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Posted 08 July 2020 - 05:54 PM

They all "work". I'd get one with a helical focuser which makes life easy. Check also the size of the prism - that will determine the field of view. Then it's up to your budget!

 

Rgrds-Ross

Thanks Ross - I have done a lot of reading and appreciate your suggestions (e.g. moon).

 

Here are two post and threads on the subject.

 

This one post #4

 

https://www.cloudyni...be-please-help/

 

And on this one post #4 also:

 

https://www.cloudyni...s-guide-camera/

Thanks for the links! The video (embedded in one) was very good. I did try to search here on OAG before I asked the question, no idea why I did not see these! I appreciate it!



#5 the Elf

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Posted 10 July 2020 - 03:43 AM

Here is a video.

https://www.youtube....h?v=S3lZcLt_zDU

plus update:

https://www.youtube....h?v=vob9IW9i4uc

I tried to pick up everyone from zero level. Hope it helps!



#6 Cdnpilot

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Posted 10 July 2020 - 09:13 AM

Here is a video.

https://www.youtube....h?v=S3lZcLt_zDU

plus update:

https://www.youtube....h?v=vob9IW9i4uc

I tried to pick up everyone from zero level. Hope it helps!

Thanks for the videos.... Watched them both.


Edited by Cdnpilot, 10 July 2020 - 09:13 AM.



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