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Started by dan janosick, 06/06/2006 11:57AM
Posted 06/06/2006 11:57AM Opening Post
am at my wits end and could really use the expertise of this group. I own a vixen 8" 800 mm reflector f/4 and all stock accessories to include the coma corrector. When I use it visually and with a dslr it performs perfectly. However, I recently purchased a st-2000xm camera with a gerd neuman filter drawer and cannot reach focus. I cannot rack the drawtube in any further to reach focus. I purchased the 2" nosepiece (baader) along with the 2" low profile adpater (vixen) and still cannot reach focus but I can see I am going in the right direction.
I was told maybe the Denkmeier OCS is the answer but I was also told not to use the coma corrector along with that, I was also thinking of the Clement low profile focuser but then that would add alot of cost (500) plus I could not use the stock coma corrector unless they could make a special adapter so I could attach my coma corrector.
I love the idea of a native f4 scope and I do not want to change the configuration that would impact the focal length any all?
Posted 06/06/2006 12:49PM #1
Hmmm, that's a tough one Daniel... (nice scope, by the way! 8) )
I'm not sure what other options would be there, besides changing the focuser assembly, or moving the primary mirror forward?

Lets hope some of our imaging gurus have some other answers...

Ivan Gastaldo 8)
Coconut Creek, FL

Ivan's Observatory
Lat 26N 16' 48" Long 80W 10' 48"
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CCD Imaging and Processing/Deep Sky - Moderator
I like to complain about everything - Moderator
Posted 06/06/2006 02:15PM #2
I would move the primary forward. It should be a fairly simple and quick procedure. However, depending on how much forward movement you need it may cause your secondary to be undersized thus robbing you of photons from the primary. You will know when you look through the collimation tools after you move the primary, or you can use the newt program and see how it affects the light cone.

even if you do have to get a larger secondary its still probably cheaper than a new focuser, although upgrading the focuser is always a good thing for imaging IMO. Will the ST2K come to focus without the filter wheel? I agree, having a native F4 system would be real nice, so I would forget about the Denk OCS or any barlow for that matter.

just some thoughts, Vince