Focusing on moon through a webcam

[ubertank]

Hi guys,

Was out with the SPC900 webcam with on the 200P dob this evening, however was having issues getting anything like a decent focus on it.

I had the webcam attached to the eyepiece holder, but it seemed that when I moved the focusing wheel (unsure of the proper name), it seemed like the webcam needed to go in a couple of turns further to get a focus. I think that if my eyepiece holder was a little shorter it may have been about right.

Am I right in assuming that I need a shorter eyepiece holder or am I missing something obvious here?

Thanks for any help guys. Tonight I was out with the webcam in the garden after being out in the country for an hour with the SLR and a tripod. So much to learn and so many questions to ask.

[JamesF]

It's a problem that seems particularly common to newts that cameras can't reach focus because the focal plane is too far down the focus tube to get the camera sensor to it.

One solution is a low profile focuser, but that tends to be expensive. Another is to move the mirror a little closer to the secondary, either by the drastic measure of shortening the tube, or by replacing the collimation bolts with longer ones. With a webcam I might be sorely tempted to cut/sand/otherwise remove the shoulder from the nosepiece to allow the camera to slide further down into the focus tube in the hope that would allow it to reach the focal plane.

Alternatively, using a barlow may shift the focal plane out far enough that the camera can reach it, but obviously you then have a much smaller field of view.

James

[ubertank]

James thanks again for your help and advice. It seems that imaging with the 200P dob and a webcam is just not going to be possible right now I guess.