I have done similar experiment with a webcam, and indeed it works great.
You can also use the camera with its lens, focussed on the main mirror,
put a small razor blade a few cm in front of it (distance depends of
size of the video CCD and focal length as well as telescope F/ratio) and
make a nice foucault test system. You can also integrate several images,
and stack them afterwards to obtain a nice foucaultgram on the sky.
Works great.
Alain

Taras Hnatyshyn a écrit :
>
> One thing I found is that when collimating my 8" LX200 that I need to wear my eyeglasses (my right eye has astigmatism). I sometimes do not view with my glasses on and my first collimation attempt actually uncollimated the scope while collimating the optical system which included my eye.
>
> I just bought a Galileo video CCD camera the other day and found that it is a convinient tool to take my eye out of the equation. The image is projected on a 5" b/w monitor so I can see the defocused star image and see the collimation screws without having to move around too much. This camera does not appear to have much application beyond this other than sharing views of the moon, but for its price, it beats the pants off the various laser collimators, at least as far as SCTs are concerned, as a collimation aid (not a tool). And since the eye is basically out of the loop (the image is focused on the CCD instead of the retina) the collimation should be better for photography/imaging.
>
> Compared to the more professional CCD cameras (Meade, SBIG, etc.) this device gives immediate feedback, no need to wait for an image to download. I have only tried this on magnitude 1 and brighter stars, the contrast in New York City's light polluted skies just doesn't allow me to see the defocused images of much dimmer stars.
>
> Now if I can get this camera parfocal with my imager or my camera body... I may have a focusing aid too... Just a thought.
>
> Taras
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