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Old 10-09-2010, 05:38 PM
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higginsdj
A Lazy Astronomer

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Join Date: Mar 2006
Location: Canberra
Posts: 614
Quote:
Originally Posted by Terry B View Post
Yes. I can image the 0th order image. The problem though was that when I image such bright stars my ST9E camera instantly blooms. I tried putting my Bahinov mask on and was able to use this to focus.
You have to focus 2 different things. The star image needs to be focussed on the slit and the CCD needs to also focus on the slit. At present I can easily focus the star using the normal scope focusser. To focus the camera requires a second focusser between the camera and the body of the spectroscope. I have rigidly connected the 2 together at present so my ability to focus the camera is limited to using different length connecting tubes with T threads on each end. I can make a fine focusser on my lathe but am still thinking about a design for it -Some sort of threaded rings that go inside each other that can be locked and have T threads on each end.
OK, I'm confused. How can you be focused on the star AND on the slit?

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