Questions about light leaks

[john7406]

John, have you tried a flashlight test in your darkroom? Place one of your holders (empty of film--if you have film in the holder, you will produce light leaks on the film doing this) in the back of the camera, then, with lights out, insert a mini flashlight into the front of the camera (through the lens board opening). Aim the beam at the upper right of the back (where your leak is, if I am following the opposite-the-film-notch description), and see if any light is coming through. Move the flashlight around until you get a strong beam aimed right at the corner. (note: you may need an assistant to handle the flashlight while you focus on inspecting the back.) Wiggle the film holder a bit as it might move with you insert/pull a ds. Try this with the bellows at different extensions as well.

Since you have an inconsistent leak, it seems to me you've got a very, very slight gap that should show up with this test. Also, try this with several of your holders. They may have slight differences in size that could be causing/masking the problem at times.

If you can find the gap, a piece of adhesive-backed felt strategically placed could eliminate your leak.

Thanks, Mike, you read my mind. I think this is the first thing I'm going to try. I don't have a darkroom, but I can cover one window in a small bathroom and that should be dark enough. Someone mentioned getting a cheap marine strobe light, that flashes once every few seconds. The good thing about that is that it's small enough to put into the camera,which would allow me to put on a lens board to make the camera completely light-tight. However, I think that your flashlight idea makes a little more sense, because I can aim it right where I think the trouble is. I can probably jury-rig some kind of clamp to hold the flashlight and keep it pointing where I want; that would free up both my hands.

I have a couple of dozen 4x5 holders. Some are relatively new and some look as old as I am (I'm 60). Some of the slides go in and out easily but others are so tough that I almost pull the camera over when I pull the slide. I'm sure the flaps are the same - some great, some horrible. If I can get this flashlight test to work efficiently, I might invest the time to test all of my holders. I'm tired of ruining images.

If I do need to fill a gap, could you recommend a particular brand of felt? I've never done anything like this before.

Thanks again, and I'll let you know how it goes.
-John

[Liquid Artist]

John,
If you have a decent sized closet it's all you really need to check for light leaks.
That is saying your wife doesn't have them all stuffed like mine does.

[john7406]

John,
If you have a decent sized closet it's all you really need to check for light leaks.
That is saying your wife doesn't have them all stuffed like mine does.

I gave up on closet equality about 20 years ago :-(

Actually, my basement is mostly below ground and has just a couple of tiny windows. It'll be dark enough for what I need to do.

[Jim Andrada]

Are you sure it isn't the holder itself? I've had a couple of corner leaks that seemed to follow the holder and I concluded that the light seal was giving up OR that I was wiggling the slide around too much while pulling/inserting.

[muihlinn]

I had a similar issue with a 5x7 back for my 8x10. Making a long story short, check the spring tension, mine felt fine but it failed doing enough pressure against the holder causing random light leaks, more common towards the top as I pulled up or down the darkslide

[Michael E]

Does your typical light leak cover the film all the way to the edge? Or is the part covered by the holder unexposed? This might help to narrow it down to the holder (seal) or the camera/camera-holder connection.

Some people file indivual marks in the hinge of each holder. If your light leaks always occur on the same side of the same holder(s), it helps to find the culprit.

Good luck!

Michael