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Old 14-06-2007, 02:06 PM
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iceman (Mike)
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Quote:
Originally Posted by bkm2304 View Post
Thanks, Mike. So the camera will autofocus looking at say, a brightish star through, say, a 26mm eyepiece? Also, what would be a guestimate for seeing the faintest object after say a 7 -10 second exposure? I know this is very hypothetical but if I look and see visually a mag 12 object, will a shortish exposure as above, see any better?
I doubt the camera will autofocus - you'd need to manually set it to infinity or if it's a DSLR then manually focus it.

You won't be able to do a 7-10 second exposure - you won't have tracking remember You'll get star trails. You'll mostly be limited to shots of the moon and planets. You could try a 3 seconds exposure through a widefield eyepiece on something like a bright glob, and with a high ISO you might get something, but don't expect great results using this method on an untracked dob.

A shorter exposure means less light coming in, so the object will have to be brighter to register on the CCD.

For non-tracking dobs, stick to planets/moon - and get a webcam!
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