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You could also use a small refractor and focal reducer. Say a second hand 80ED and a 0.5x (1 1/4") focal reducer which would give you a focal length of 300mm. By adjusting the placement of the FR you can control the focal length and so optimise your field of view to mach your webcam. It is then also easier to fit a solar filter and mount the optic. This way you will have a system with minimal chromatic aberration for relatively low cost. Any 'cheap' telephoto will have chromatic aberration that really shows up at the pixel size of a webcam.
You could also use a H alpha filter WITH a solar filter to minimise chromatic aberration.
Bert
Last edited by avandonk; 25-08-2008 at 08:36 AM.
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