I am currently doing a science fair project on variable stars. All I have to do is take a picture of a variable star. Since I only need to take a snapshot, I don't really need tracking. I recently bought a t-ring and a t adapter for my Canon EOS 400D to fit into my dobsonian. I tried it out last night on the moon, but couldn't get it to focus. As I turned my focuser in towards the scope, the imaged started to get in focus, but I was unable to fully focus the image since I was unable to turn my focuser any more. I know that this is a common problem in Prime focus astrophotography, and that I might be able to fix it by moving the primary mirror, but I don't really feel comfortable doing that. If I need to do that, I will, but are there any other alternatives? Any suggestions would help a lot. Thank you.
Prime Focus Help
Started by torocorgijr, 10/12/2008 04:13PM
Posted 10/12/2008 04:13PM
Opening Post
Posted 10/13/2008 10:42PM
#1
In most cases moving the primary up is the easiest solution. Another alternative would be to swap out the focuser for a low profile one (if it doesn't all ready have one).
At prime focus you're going to have a lot of stars in there. I would maybe try low power eye-piece projection to narrow the field down some, plus focus shouldn't be an issue. Only problem is you'll need a brighter variable star to minimize the exposure time since you have no tracking.
Robert
At prime focus you're going to have a lot of stars in there. I would maybe try low power eye-piece projection to narrow the field down some, plus focus shouldn't be an issue. Only problem is you'll need a brighter variable star to minimize the exposure time since you have no tracking.
Robert
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