Thread: Focal Reducer
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Old 06-04-2007, 08:16 PM
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Blue Skies (Jacquie)
It's about time

Blue Skies is offline
 
Join Date: Nov 2005
Location: Melbourne
Posts: 1,221
Hmm, I'm surprised no one else has jumped in on this yet, perhaps they're all away for Easter.

I am curious about the fact that you were sold a focal reducer for a newtonian. In my previous experience focal reducers were only for Schmidt-Cassegrains (SCTs). SCTs have HEAPS of focuser travel and this issue you're experiencing wouldn't occur. So if someone has anything to say about this I'd be interested too.

Otherwise I have a couple of suggestions:

1. If you can't acheive enough intravel with the focuser in the dob you will ned to move your primary mirror up the tube when you plan to do imaging. When you want to do some visual viewing you will need to move it back down again. A bit of a hassle, and you would need to collimate every time you shift (so if you're not confidant with that I'd get practising). I would not be able to tell you how far you need to shift, though, in this situation.

2. Buy another scope that has a short focal ratio already and use that for widefield imaging. Don't laugh or scoff, thats what a lot of serious astrophotographers do - get the right tool for the job.

3. Forget about the focal reducer and invest in some good software that will stitch your smaller images into a larger mosaic. Perhaps a visit to the software forum here will help you out.
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