Questions about light leaks

[john7406]

Hi all, I've been lurking on this forum for some time, and thanks to you all, I've earned many things.

I've read through the light-leak section, but I have a few questions.

I'm currently using a Wisner 4x5 field and about 50% of my images contain light leaks. They appear to be random. For example, side A of a holder may show a leak while side B of the same holder produces a perfect image. The light leaks appear as a "spray" of light from the corner opposite the film notch. Sometimes it looks like just a spray, other times, half the negative is white. Other times there is a leak but it's barely noticeable. But in all cases, it seems to originate (or at least include) the corner diagonally opposite the ID notch. This tells me that the leak is originating from the upper part of the loading area.

In almost all cases, the leaks are "partial", in the sense that the image is still visible (though badly white-washed). I've had very few leaks that obliterated the image completely. All of this tells me that it has to do something with the way I'm handling the slides. The leaks appear to be transitory, momentary things rather than the result of prolonged exposure.

I'm fairly certain that the holders are well-seated before I remove the dark slide, and I remove the slide maybe 15 seconds before I fire the shutter, and replace it immediately. The leaks don't appear to be dependent on ambient lighting - photographing in bright sunshine doesn't cause any more leaks than shooting in a dark forest.

I also made many, many images with a Wisner 8x10 (with Lisco/Fidelity loaders) as well as a B&J 4x5 (with Readyloads), and I never had a single leak. Unless someone has a much better idea (a very likely possibility, believe me), I'm planning on doing a few dozen test shots in my basement to see if I can isolate the cause. But I'd rather shoot my images in the field :-(

There was one post in the light-leak section warning you to insert the dark slide squarely back into the holder. I admit that I sometimes put in a corner of the slide first before sliding in the rest of the slide. I was wondering if any of you had any experience or troubles with this type of thing.

I use only plastic holders, but I was wondering if some of them could be warped enough to prevent a tight seal inside the camera. I'm kind of hoping that I have a few duds and I just haven't been clever enough to identify them, but I think this is happening too often to be a holder problem. I guess this is another reason for a comprehensive test in the basement.

Any guidance or information would be greatly appreciated.
Thanks to all in advance -:)
-John

[Liquid Artist]

I can only guess here. The bellows has a corner light leak which gets bigger as you open the bellows up.
Covering up the bellows with your dark cloth will sometimes eliminate the problem. A corner leak is often easy to patch from the inside too making it impossible to tell by just looking

[Ken Lee]

When we remove and replace the dark slide, the holder can move and a slight gap can appear briefly. It only takes a fraction of a second.

For that reason, it's important when removing and replacing the dark slide with one hand, to pinch the camera back against the film holder with the thumb of the other hand. If this isn't clear, let me know and I'll post a photo.

Another trick is that because holders get stiff with age, greater effort is required to pull and replace the dark slide: polishing the edges of the slides with a bit of wax helps a lot.

Even when they're polished or new, it's important to hold the camera back against the holder so that nothing can budge, even on cameras that have strong springs to hold the back in place.

[Ken Lee]

http://www.kenleegallery.com/images/forum/SqueezeBack.jpg

Here's what I mean: we squeeze the back tightly closed before removing/inserting the dark slide, even with a Sinar whose back has a fairly tight spring.

[Jim Noel]

I agree with Ken about holding the back while removing and inserting the dark slide.
Additionally, I keep the bellows and back of the camera covered with the dark cloth at all times. I learned from Cole Weston the value of using a large dark cloth. His reached almost to the ground and he kept his film box under the tripod. When he opened the box to get a holder, it was shielded by the dark cloth so it was never struck by direct light. My largest dark cloth is 5x8 feet and accomplishes the same purpose. I don't get light leaks.

[biedron]

Another thing is to make sure that you are inserting the film holder from the correct side of the back. I have this issue with my Arcas. While you physically can insert the film holder from either the left or right side (or top / bottom) of the back, only one side leads to a properly seated holder and creates the light seal. Inserting the film holder from the incorrect side can lead to random light leaks. Not sure is this is an issue for you or not, but it might be worth checking. I recently added a label on the correct side of the backs to the effect of "insert film holder from this side" - hopefully I will see and heed that :)

Bob

[john7406]

I can only guess here. The bellows has a corner light leak which gets bigger as you open the bellows up.
Covering up the bellows with your dark cloth will sometimes eliminate the problem. A corner leak is often easy to patch from the inside too making it impossible to tell by just looking

Thanks. These days I'm doing a lot of shooting that doesn't require much extension, but I understand what you mean. I might do a "lightbulb-in-the-camera" test to see if I can see any bellows gaps.
-John

[john7406]

Thanks Ken, I hadn't thought of that, but it makes sense. Ironically, when I pull the slide I tend to hold on to the tripod, just to make sure I don't move the camera or even tip it over. That might give you some idea of how hard I have to pull some of the slides. So, you might be right about polishing.

I'll definitely start "pinching" whenever I'm "pulling" or "pushing". The photo you posted also helps a lot.
Thanks again
-John

[john7406]

Thanks Jim, and I hear you. I try to cover as much of the camera as I can, but I've never covered the loading slot. I have maybe a 5x6 heavy dark cloth (originally used with 8x10) and I use it with the 4x5. I tend to photograph in windy locations (Montauk - the eastern tip of Long Island) and the dark cloth acts like a kite. I usually wind up using rocks or other things as weights to keep everything from flying off.

I guess one thing I could start doing is cover the whole camera with the cloth and then reaching under and removing the slide by feel. It's the "putting-back" part that makes me nervous, but I guess I can practice. I've never had trouble loading holders in a changing tent (though 8x10 is much easier than 4x5 IMHO), so I guess I can figure out how to re-insert a slide by feel as well.
Thanks again.
-John

[Michael Roberts]

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.

[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