Webcam Sensitivity

Forgot to ask - anybody any idea what's the faintest magnitude of a star that a modified webcam can pick up with a 70mm refractor as a guidescope would you say??

or would I need a bigger guidescope, say 90mm?

Keith..

I can tell you now that I can just about pick up Neptunes disk in a 12" scope with my unmodified toucam, so with a 70 mm scope I'd imagine you'd be pretty limiteds as to what stars you could use, maybe mag 2 or 3 at a stretch ?!?

Thanks Dave, looks like i'll have to get a large guidescope so....

Keith..

Keith,

A modded webcam will easily pick up 10th mag stars, probably a lot fainter too. You'll be fine with a 70mm scope.

Thanks, where can I get a modified webcam?

Keith..

Keith - if you are piggy-backing a guide scope just beware of flexure between the two OTA's - make sure you you get a quality mounting system to mate the two. Just pointing it out to help you avoid a gotcha!

Dave