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Edge 8 and Celestron OAG....Backfocus

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#1 SandyC8

SandyC8

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Posted 13 April 2021 - 11:01 AM

Hi,

 

I have read all of the posts here about back focus and the Celestron OAG. I'm trying to set up my first OAG on my Edge 8 (or any other scope for that matter). So, I have no idea what I am doing. I decided to use a Celestron OAG due to the mirror size and the fact that it's seems to be designed with Celestron products in mind.  

 

I put together the following in the imaging train.: .7 reducer, the OAG, Starizona filter drawer and an ASI 294 MC. the guiding camera is an ASI 290.

 

I have done a direct measurement from the lip on the reducer back to 6.5 mm from the front of the camera. It measures (as best I can) 105mm.  Using Sharpcap during the daylight on a cell tower a mile or so away, both the primary and guiding camera focus. I haven't tried it at night yet.

 

I have included a picture of the imaging train.

 

Hoping for a few comments and opinions.....

 

Thanks......

Attached Thumbnails

  • OAG.jpg

Edited by SandyC8, 13 April 2021 - 11:03 AM.


#2 nemo129

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Posted 14 April 2021 - 05:24 AM

It sounds and looks like you did everything right. For me, I usually set up a spreadsheet with the thickness of each imaging train component including the backfocus of the camera to get a idea of how I am doing for spacing, but it is not absolutely necessary. You just need a clear night to take a picture of a well focused star field and check the stars across the FOV. Good luck and clear skies!



#3 SandyC8

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Posted 14 April 2021 - 03:22 PM

The Starizona filter drawer is the one I used with my RASA 8......seems to fit perfectly.




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