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Old 13-12-2009, 06:13 AM
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pmrid (Peter)
Ageing badly.

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Join Date: May 2008
Location: Cloudy, light-polluted Bribie Is.
Posts: 3,742
Quote:
Originally Posted by multiweb View Post
Hi Tommy, best thing is to remove the back of the finder all together, stick the QHY5 flash with the tube and check if you can reach focus with the front rings. That should give you an idea of how far you are in or out.
I cut 35mm off the back of a cheap 9 x 50 and turned down a bit of aluminium to slide snugly inside the tube (with a couple of locking screws) and to give a 1 1/4 inch slot for a DSI that now sits happily in place, finds focus with the help of a lock screw and also adjusting the primary lens cell a bit. I'm going to test the theory that guiding systems operate at a level of about 1/15th of a pixel accuracy so according to theory (with seeing rarely being better than 1-1.5 arcsec/pixel anyway) that this system (with a focal length of about 150mm) should be able to guide anything up to 2000mm FL or so. I know this conflicts with conventional wisdoms, but what the hey!! It'll be interesting to see the results.
Peter
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