building my own "videotap"

Olivier Egli · March 12, 2004

hi everyone

I have this nice 16M that I love and I am going to use it some more for handheld shots where I need good control of the framing and composition. Not for anything else..

So I thought of using some kind of a lipstick camera attached to the viewfinder and connected to a LCD monitor.

I found a really tiny CCD camera that would fit with some minor modification into the eyepiece.

my question:

1.) do I have to detach the whole viewfinder for it or can it be done at the eyeglass?

2.) will the ccd camera (as it is probably autofocus) hold the focus or will it constantly change as it looks for focus?

3.) does it work at all?

4.) is there a better way to do it?

5.) Is the light sensitivity of 0,5 lux a problem?

the camera has a focal length of 3,6mm, has auto iris, weights about 27 grams and uses 12 volt.

If this works I will have my friend, a metalworker, to design and build a custom connecting ring of the camera to th eyepiece to shut down light. The idea is to pad it with some foam and/ or rubber so it nicely snugs over the eyepiece.

the camera I intend to use:

Phil Rhodes · March 12, 2004

Hi,

I doubt the camera you're thinking of has auto focus. It's probably so wide, so sensitive, and therefore such a small aperture, and has such a tiny CCD and therefore a huge depth of field, that it isn't required. At worst you'll have a threaded lens insert on the end to adjust with.

I'd just use one of those tiny, cheap security cameras for something like this.

Phil

Olivier Egli · March 12, 2004

hi phil, you are right

It probably doesnt have autofocus, dumb me!

and it is thought as a security camera. and the major pont is: it is really really cheap! About 50 bucks!! on discount. so I should run for it, you think?

what about the mount? to the eyepiece or take off the viewfinder for it? it probably doesnt matter, right?

March 12, 2004

How about using a waterproof digital still camera, in movie mode, set to macro, and attached to the viewfinder? I think that Pentax just came out with one. It may be available in the US already; or using a digital camera in waterproof housing.

Maybe you can get a complete security system, that is a small B/W camera with a monitor. But you need something that's waterproof.

How about using DVX 100a or PD170 (you can deinterlace the image later) in waterproof housing?

Mitch Gross · March 12, 2004

You will likely need a spacer lens to get it to focus properly and cover the image size correctly. Edmund Scientific is the place to go. You'll also need a ring clamp of some kind to attach it to the eyepiece. I've seen them made for both the eyepiece on and the eyepiece off, but your's would likely be eyepiece on.

You can buy ready-made versions for around $300, and by the time you work this out it may be cheaper & better to do just that.

Michael Nash · March 13, 2004

It sounds like the kind of thing you'll have to spend some time tinkering with. The final product can probably be build pretty cheap, but the trial-and-error period will cost you some time and expense. I'd say go for it, but don't expect it to be perfect right away.

Olivier Egli · March 13, 2004

alright, I bought the 3,6mm security cam and the 2,5 inch LCD monitor.

Should be here sometime next week. My friend builds a ring tap to attach to the eyepiece.

But Mitch, what is a spacer lens???

Mitch Gross · March 14, 2004

A spacer lens is a general term for a lens that focuses an image off of another lens as opposed to the open air world around it. This is essentially what you're doing when making an eyepiece tap. The question is what size lens you'll need and how close it must focus. I have no idea.

Olivier Egli · March 15, 2004

aha, I have never heard of this expression. I odered this pen lens with the 3,6mm optic.

I remember having taken still pictures and also some video off the eyepiece as a joke during my last music video shoot. And the pic was fine. So this will probably still work out...

TJ Williams · March 19, 2004

I built somthing similiar a while back to look into the viewfinder on Sony HD cameras

as a backup to downconverting. The lens was about 4mm Many of these little cheap cameras mount the lens on threads. If you unscrew the lens slightly it works like macro and you may be able to focus closer. The big challenge was placing the camera far enough down the eyepiece to cover the correct area. If you remove the outer eyepiece and put a black painted cardboard tubo over it with tape place the camera on a stick and move it down in the tube trying to find the sweet spot, then measure how far up and how far off angle. Try machining the holder out of deldrin a cheap black easily machinable plastic which is very rugged.

TJ