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Edge hd external focuser

Beginner Celestron Catadioptric Accessories
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#1 TintiNite

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Posted 18 June 2021 - 10:46 PM

Real newbie here!

 

If focusing via primary mirror movement is not ideal, can you lock the primary permanently and use an external focuser?

 

Thanks



#2 james7ca

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Posted 19 June 2021 - 02:59 AM

Yes, I have that exact setup on my 9.25" EdgeHD. I still use the built-in focuser for rough focus, but then I lock the mirrors and use a 2" Feathertouch Crayford focuser for final focus. That said, the mirror locks on the EdgeHD won't really keep the primary mirror from moving, they just make it less likely to move. I also unlock the mirror at the end of the session.


Edited by james7ca, 19 June 2021 - 03:04 AM.


#3 rmollise

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Posted 19 June 2021 - 01:28 PM

It really shouldn't be an issue. In most modern scopes, focus shift--if that is your issue--is less than 45". Also, the Edge has different requirements for spacing on the rear cell compared to the standard scopes. Be sure to take that into account.


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#4 Linwood

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Posted 19 June 2021 - 07:33 PM

And especially if you are new to using it, just wait until you settle into a routine, i.e. what kind of imaging train you plan, since backfocus and potentially rotation (auto or manual) become a thing, and the train (mono or color, filter wheel, etc.) can make a lot of difference. 

 

Also, as @rmollise says, make sure you are fixing a problem you have, not just one you read about.




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