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Old 19-04-2008, 03:31 PM
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Kirkus (Kirk)
Beginner-ish

Kirkus is offline
 
Join Date: Dec 2007
Location: California, USA
Posts: 207
Back focus problem

I learned a little something tonight on IIS (who needs Google?). After attaching my DSLR to my 6" Meade (Schmidt-Newtonian) I discovered that I can't rack the focuser in tight enough at prime focus to attain focus. Thanks to the search feature here, I learned that this is a "back focus" issue. I also learned that my options are to either move the primary up the OT (bleh!) or try a low-profile focuser.

I also have my 10" Celestron reflector that I'm able to use on my mount (I really wanted to use the 6" for my DSLR because it's so much easier to set up and is less strain on the mount). I took a rough measurement and the focuser on the 10" is about 50% the distance from it's base to the eyepiece hole than the focuser is on the 6". But there's also a focal length difference of about 500mm between the two scopes. I wonder if that will be enough for me to rack the DSLR in tight enough?

I'm going to try it on the 10" tomorrow night.

(I rambled on about all that just to get to this question) Are there any other options I might have other than moving the primary up the OT or trying a low profile focuser?
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