Imaging the moon using webcam on CPC 800

[bigbaldyal]

Hi all, I've been trying to image the moon using an xbox live webcam that I've modified for telescope use on my Celestron CPC 800 but I'm having trouble getting the whole moon in shot. I've not used a barlow lens. I'm sure there's a way of doing it & wondered if anyone has any ideas. Please see image for my problem. Moon 1.bmp

[silios]

At the focal length of 2032 mm that your scope have, you would need a focal reducer in order to get the full moon in frame.

Use this field of view calculator to have a feeling of the objects you are about to shoot.

[ngwillym]

With the focal length of the CPC 800 and the small chip size of the webcam, you're not going to be able to get a whole disk view in one go. By the look of it even using a 0.5 focal reducer still won't show the whole disk. The other option is to stick multiple images of different parts of the moon together (a technique called making a mosaic).

[JamesF]

Yup.  From memory you need a focal length of about 400mm (and perhaps a bit less) to fit the entire lunar disc onto a camera sensor the size of the one in the Xbox camera.  You'd need something like a full-frame DSLR to get the Moon in one frame at the native focal length, or a crop-sensor DSLR should do it in two frames.

James

[bigbaldyal]

Thanks for your advice. I'll try my dslr. I've got a sony Donkey which I think I can use as a live camera.

[bigbaldyal]

That should read Sony Donkey camera

[bigbaldyal]

It's done it again. Try it this way. Sony alpha 55 camera

[JamesF]

You don't need to capture a video.  You can stack still frames.  I wrote up a little "how to" on the process some time back.  Ideally you want a T-ring for the camera and then you can put it straight on the visual back.  That will also mean you get a slightly shorter focal length when the image is focused which will help with fitting as much of the lunar disc on the frame as possible.  In fact you may get away without needing a mosaic as long as the Moon isn't too close to full.

James

[JamesF]

It's done it again. Try it this way. Sony alpha 55 camera

 Gotta love the forum's robot censor.  It can be excessively literal and brain-dead.  Took me a while to work out what was going on there

James

[knobby]

I reckon , two halves with a DSLR ... Full moon just fits my D7200 on C8 with 0.7 reducer

[JamesF]

Here you go.  This might help you along the way: http://stargazerslounge.com/topic/184192-full-disc-lunar-imaging-with-a-dslr/

James

[JamesF]

I reckon , two halves with a DSLR ... Full moon just fits my D7200 on C8 with 0.7 reducer

That's consistent with what I get using my 450D on my 127 Mak I'd say.

James

[JamesF]

In fact you may get away without needing a mosaic as long as the Moon isn't too close to full.

I meant to be clearer about this...  With tonight's Moon for instance, if you turn the camera so the image is "across" the frame rather than "upright", I reckon you'd get the entire visible part of the Moon in the frame and perhaps that might be possible for another three or four days.

James

[bigbaldyal]

Thank you everyone for all your comments. I'll take them on board. I'll try using my DSLR and maybe get a focal reducer to try with the webcam. Ultimately I'd like to get a decent CCD imaging camera but thought the cheapness of the xbox webcam was worth experimenting with.