More noob issues - web cam ccd

[Insane Climber (Jason)]

Hi guys me again with another problem, i have made a camera useing a webcam ccd, i machined up a housing and mounted it to a 32mm camera projection lens (1 1/4") The idea works quite good. However i cannot get enough field onto my ccd, mainly because the webcam ccd is so small. I tried a 0.5x reducer but it just totally stuffed my focal range. Can anyone suggest a way to focus the field correctly onto my tiny ccd.

[Blue Skies (Jacquie)]

Yes, get a different (smaller) sized telescope.

I'm not sure what you are trying to achieve, but there is not much you can do to increase the field of view without changing the scope. That's why the short tube 80mm refractors are so popular! They give a wide field of view. And thats why astronomers get so excited about how big they can get their CCD chips!

Or you could become an expert in mosaics...

[Insane Climber (Jason)]

Well this ain't goin too good. i have been trying hundreds of different combinations of barlows, camera projection lenses, reducers, even built a sleve so as i could drastically move my focuser, and of course tried prime focus. and now you tell me that i just have to make do with what i get? surely there is a way to correct the field.

[Insane Climber (Jason)]

Here is where im at, this is the widest FOV i can get

[Zuts]

Hi,

I assume you are doing everything at prime focus. The problem you have is that you cant increase the chip size as it is fixed, all you can change is the focal length of the scope. You can try using focal reducers but how far can you go?

I guess if you didnt want to use a telescope and could somehow fix a telephoto lens to your webcam you may get a better field of view, say an 18 mm lens but what would the quality be like with so few pixels on the webcam.

Most people use webcams for planetary stuff or accept the magnified view they get.

If you want to see how your FOV changes with chip size and FL then download a free program called CCDCALC. It gives standard pictures of DSO's and you can vary the chipsize and FL to see what your result would look like.

Cheers
Paul

[Insane Climber (Jason)]

Thanks paul, i will try that programme you mentioned. The way i have been thinking is that if i were to place a small convex lens in front of the ccd it would, if it could be moved, allow me to correctly size the field of view onto my ccd. I went looking for such a device and found that field correction lenses do exist for some cameras. however no one makes any thing for a small crap web cam ccd.

[iceman (Mike)]

hi Jason

That's normal - in fact with webcams, most people want a MORE magnified view - not less.

You'll need to use a DSLR rather than the webcam, or use a 300mm lens attached to your webcam, if you want to fit the whole moon on.

[Insane Climber (Jason)]

After doing alot of reading i have discovered that a 0.7 - 0.5 reducer should give me a good focal reduction without warping the image too much. This just leaves me with a focus problem. I see that some astrophotographers shorten there newt's, is this why?

[iceman (Mike)]

Hi Jason

Newts are normally shortened (by 50mm or so) so DSLR's can come to focus at prime focus. It may be the same for a webcam with a reducer.

[bmitchell82 (Brendan)]

I think we have another Project& Article to put up

[StevenA (Steven)]

This is just a thought, but why not take several images of the moon and put them together using a mosaic program such as IMerge. or take an AVI moving around the entire surface and then seperate them and finally mosaic them together using forementioned program. It's easy to find on the net.
Just an idea and it saves money.

[Insane Climber (Jason)]

unfortunatly the web cam auto adjusts its own exposure and gain. which makes it very hard to match in a mozaic. However i have gotten sick of the poor sensitivity of my web cam, and purchased myself a DSLR. So now i just need a T-mount adaptor, I hope. Anyways I was never worried about fitting the whole moon in, it just seemed to me that i was only useing about 1/10th of my Apature?