Film SLR body as webcam host - pros & cons?

[omaroo]

Hi all

After musing over a photo of the Pentax film body with the webcam PCB mounted inside shown below, I've been thinking of doing the same to my Nikon N50 - which I will probably never use again as a day to day unit as I still have two other film bodies that are far more valuable to me (Nikon F and Nikon EL) and now the D40 DSLR. I paid $50 for it on eBay so it's absolutely perfect for the job. It still mounts all my Nikon lenses - which is why I'm interested.

After getting involved in my peltier-cooled webcam project I think I'd also like to try doing the film-CCD conversion on the N50 as a bit of fun. It looks relatively easy to mount the webcam PCB with the CCD still mounted where it should be right on the film plane from the back. If I remove the film pressure 'sled' then it would leave plenty of room for the board.

Now - what would I end up with? Do the camera's electronics become irrelevant just because I'm exposing to CCD rather than film? I guess so as the webcam isn't designed to be exposed for a brief time, but rather outputs a constant video stream. What if I were to perform a long exposure mod on the webcam - would it work the way intended then as the shot would trigger the mirror to flip and the shutter to open - exposing the CCD for a brief time?

The N50 doesn't have mirror lock-up, but it does have a bulb setting - so normal video streaming mode would work if this were set. I've just tried it and the mirror stays up with the shutter open until I re-press the shutter button.

The bulb feature works to keep the mirror up and the shutter open - and once I replace the battery with an externally-wired 6v DC source power shouldn't be a problem. At this stage I don't plan to use the timed shutter - but to just keep it open so that the webcam can operate as a normal streaming video device to capture moon or planets - only with a nice Nikon lens up front.

I don't plan to actually remove anything as such - it's purely a mechanical job to mount the CCD and board on the film plane with very minor modification. There's even four beautifully-placed screws on the backplane that will aid in mounting the board. I'd have to remove the little speaker from the webcam's PCB - but that's a no brainer as it serves no purpose anyway.

The question I have is what reaching focus will be like - as the focal plane is in the same place - the only difference being the size of the sensor in comparison to the size of a 35mm frame. I hope that I can center the CCD to picj up a 640x480 pixel "window" within the 35mm frame.

Any ideas anyone?

Cheers

Chris

The Pentax (from "Digital Astrophotography: The State of the Art" by David Ratledge (Ed) from Patrick Moore's Practical Astronomy Series, published by Springer)

The Nikon N50 - nice and cheap on eBay!

[Ant]

Hi Chris,

There is a guy in Australia who makes webcam adapters so that you can match up your webcam to camera lenses.

I bought one a year or two back to "mate" a Toucam Pro to the Olympus T thread. Worked a treat the focus point is the same (so infinity on the lense was in focus for the webcam).

http://moggadapters.com/astro/adapter.asp

I know that this doesn;t answer your question, but it might help.

Ant

[omaroo]

Thanks Ant. Yes, I've seen these before and they certainly look very useful. They even include the tripod mount thread.

I still like the idea of experimenting with setting the webcam up in long exposure mode and using the shutter at various speeds to see what happens. I'd like to think that I could use single frames as it were. Even if the camera was set to normal video streaming mode at say 30 fps, the shutter could be used to "still capture" moving objects.

I guess it's coming down to the experimentation factor that I like the idea of....

Cheers

Chris

[Ant]

Hi Chris,

I've just been reading all about your webcam cooling mod. I thought to myself then that you're not going to be too interested in buying and "off the shelf solution".

I wish you luck. Certainly looks like you have a lot of fun making things yourself. Me, I couldn't even re-house my toucam into a project box with doing damage... it was never the same again!!!

Ant

[omaroo]

Thanks Ant

Half the reason I wanted to do this was because of the viewfinder. When centered, I could mark the effective FOV of the CCD on the prism somehow - and that would give me a way to focus without seeing output to a screen.

[Naz]

If I remember correctly, KK has already modded a film camera for this purpose 8)

naz

[omaroo]

If I remember correctly, KK has already modded a film camera for this purpose 8)

naz

Naz - was there a thread about it?

Cheers

Chris

[Kaptain Klevtsov]

Take a look here http://www.gas.uk.net/webcam/index.htm

I fixed the webcam to a lump of wood so that I could centre it. The best bit is that if you look through the viewfinder of the camera you get a much bigger FOV than the webcam sees. Centre the planet and open the shutter (which got bashed offf in my case). This moves the mirror up and the planet is bang on the chip (well, close, anyway).

Have fun, and I hope it works for you.

Kaptain Klevtsov

[omaroo]

Take a look here http://www.gas.uk.net/webcam/index.htm

I fixed the webcam to a lump of wood so that I could centre it. The best bit is that if you look through the viewfinder of the camera you get a much bigger FOV than the webcam sees. Centre the planet and open the shutter (which got bashed offf in my case). This moves the mirror up and the planet is bang on the chip (well, close, anyway).

Have fun, and I hope it works for you.

Kaptain Klevtsov

Thanks for that Kaptain! I didn't realise that you'd done it before. Great info. Can I ask - what was the reason you removed the shutter for?

Yes - the expanded FOV is what I was after - and in my case I'll find my object with the mirror in position and then fire off the bulb feature to lift the mirror and open the gate (shutter).

Cheers

Chris

[Kaptain Klevtsov]

The chip in the webcam that I used is recessed into a hole in the plastic case. To get the chip in line with the film transport rails I had to have the camera too far forward so that the shutter caught on the webcam. I was hoping to be able to centre AND focus using the viewfinder but in hindsight I'd go for just centring and do the focus later. That would allow the SLR to be used more or less unbutchered with the webcam further back out of the way of the shutter.

Kaptain Klevtsov