Webcam - too much zoom and cannot be adjusted?

[Jasp05 (Aaron)]

Hi guys,

I picked up an 8 inch Dob over christmas, which came with a whole bag of goodies. one of them being a webcam for the scope.

Now its one of these chinese ones. No real brand name on it. I've only tried it on the moon and it worked quite well. However it is zoomed right in and I cannot get it to zoom out.

It came with some software called Future Winjoe. Has very few settings for adjustment none of which have anything to do with zoom.

Does anyone know of some other software that can be used for webcam capture, or know how to adjust the zoom?

[billdan (Bill)]

Hi Aaron,

There's not much you can do about the zoom I'm afraid.

Webcam sensors are small, usually 640 x 480 pixels (VGA standard) that's why it looks zoomed in. The only alternative to get a wider FOV is to use a camera with a larger sensor.

Cheers
Bill

[sil (Steve)]

Firstly, Sharpcap or FireCapture are both free camera capture software used by many astrophotographers.

Secondly, it could be the camera is not at the focal point for the focuser on the telescope. Because of the small sensor size it may mean your focuser can't wind in far enough to focus properly. Equally it could be focusing just fine, also because of the small sensor size the magnification amount is huge and as you increase magnification there is a rapid degradation/blurring of the image as atmospheric conditions affect what you can see clearly. eg look at the moon with a 20mm eyepiece or 10mm and it should looks clear and sharp to your eyes but if you have a 6mm eyepiece or smaller it'll look swimmy and blurry. webcams tend to behave approximately like a 5mm eyepiece and they only see a small area inside that field of view. Its why you need to capture video then stack the best few hundred frames to try to average out the blur movement and run wavelets to focus or sharpen up the resulting data.

Its not like taking a photo of you dog in the backyard with a regular camera.

[Jasp05 (Aaron)]

Thanks guys. Your response about the webcam acting like a 5mm eyepiece is about the magnification I'm getting too. It focuses fine. But it's just got huge magnification.

Are there any webcams that have a wider field of view? wide enough to get the whole moon?

I'm thinking the zoom of this webcam will be ok for the likes of Jupiter & Saturn however.

[Jasp05 (Aaron)]

oh and another thing. I have the option to change the resolution the webcam operates at. it can go 1024x768 i think it was. It's set on the highest resolution at the moment anyway. And still way too much zoom.

[billdan (Bill)]

There are webcams from Microsoft or Logitech that have a wider sensor, but adapting them to fit a telescope becomes an issue.

The Moon is 30 arcmins wide so you would need a large sensor to cover that area with your 8in scope (almost APS-C size).

Better off getting a camera designed for telescopes, check out this ZWO buyers guide that has heaps of info on FOV of different cameras.

http://agenaastro.com/zwo-astronomy-...a-buyers-guide

Cheers
Bill

[jsmoraes (Jorge)]

when you use telescope with camera you HAVEN'T magnification (nor zoom). Cameras are flatten surface, not lens.
The "apparent magnification" is resolution (image scale, arcsencod per pixel). Large sensor can "see" larger field.
To do wide field with camera (or webcam) you must use reducer.

With lens and with magnification: magnification = Fo/Fe
http://jsmastronomy.30143.n7.nabble....91/optica1.jpg

With cameras: (there isn't Fe, so there isn't magnification)
http://jsmastronomy.30143.n7.nabble....onlycamera.jpg

note:
"webcam acting like a 5mm eyepiece "

Warning: if the 5mm eyepiece has an AFOV of 80 degrees, it will show more field than an 5mm eyepiece with AFOV of 50 degrees.