Webcam imaging without removing its lens

[smolloy]

Hi all,

I found a webcam in a second-hand shop today for under 2 pounds, so I reasoned that even if it doesn't work, I'm only out by the price of a coffee!

It's a Logitech V-UAP41 (I don't have the box or instructions so I don't know its full name), and it looks like I would have to break the plastic to remove the internal lens. Since it was so cheap, I don't really mind doing this, but I was wondering if there was a way to use it without doing this.

If I think of trying to image with the telescope EP still in, then the light rays emerging from the EP will be parallel. In this case, I would have to set the focusing of the webcam to infinity to get a good image. If this wasn't possible, then I could set the webcam focus as far out as it allowed, and play with the focusing of the telescope to get the rays to diverge a little when emerging from the EP.

Trying to image without a telescope EP would require me to set the webcam focus to a point very very close to its lens, but I have just confirmed that it is possible to set the focus only a few mm away.

So, if my reasoning is correct (HA!), then it should be possible to image without breaking the webcam open. Is this true? Perhaps the quality of the webcam lens is too poor for this?

I'd appreciate any comments you have.

Thanks for reading,

Steve

[Merlin66]

I think the pain would exceed the gain.....

[smolloy]

I think the pain would exceed the gain.....

What would the pain involve?

[Merlin66]

Supporting the webcam, aligning it with the exit pupil, setting the lens to the 'correct' focus and then actually taking the image. The FOV will be very small.

It's much easier to work without the webcam lens and add a nosepiece, mount it iin the focuser and have fun.

[smolloy]

Thanks Merlin66.

I took your advice and hacked it apart, as you can see in the attached pics.

Now I just need a T-ring adaptor, and a metal box to store it in, and I'm good to go, right?

[Merlin66]

Mounted in a small plastic box, you could use an old film canister (cut the bottom off) as a 1.25" nosepiece.

I'd suggest a 1.25" nosepiece rather than a T thread adaptor...gives you more flexibilty...

[smolloy]

Interesting. So I would just have to mount it in a box, and glue on an old film canister (or anything else that will fit snugly into the telescope EP holder), and then start having fun?

I guess the main things I have to be careful of are to get it well centred in the nosepiece, perpendicular to the light coming from the secondary, and well shielded from stray light. Anything else?

Thanks for all your help with this. I really appreciate your time.

Steve

[Merlin66]

Steve,

I think you've covered most of the bases...have fun!

[RikM]

Could you stick back in the original casing and glue a tube on the front or (case being round) would that make it much more difficault to get the chip perpedicular?

[smolloy]

Could you stick back in the original casing and glue a tube on the front or (case being round) would that make it much more difficault to get the chip perpedicular?

That's a very interesting idea. Enough of the outer casing survived my hacking that that is definitely a possibility, and it would certainly make it a lot easier to centre the CCD. Also the front face of the casing is flat, so that should make it possible to keep the sensor square to the light path.

Now all I need is a suitable tube with a face that I can cut a hole into. Time to raid our garage (full of junk) I think!

[Planet Reach]

You didn't have to strip it from its casing. The front lens just snaps off.

Get a 35mm camera film the canister is what you want. Cut the bottom off and tape it or crazy glue it to the camera .

[smolloy]

You didn't have to strip it from its casing. The front lens just snaps off.

I thought that, but once I had the thing open, I could see that the lens was physically screwed to the circuit, so the only was to take it out was to do what I did.

I kinda wish I'd taken pics of the process now I'll post pics of the final construction.

[smolloy]

In fact, you can see the lens holder in one of the photos I posted. It's the circular black object at the bottom left, and it screws into the two holes you can see in the circuit board on the other photo.