View Full Version : Flare? or Light Leak?

jon walker
11-Feb-2004, 04:32
Hello everyone. This is a question from a relative newbie, but not I think as obvious as that might imply. I am getting what look like light leaks down one (and sometimes more) edges of my sheets of 5 by 4. Most commonly, they are on the edge closest to where the dark slide goes in, but can sometimes be on the other edges too, or even on one of the other edges instead of the dark slide edge. They are always in diffuse bands parallel to the edge of the frame, but not necessarily starting right at the edge. However, the slides are all new Fidelity ones, so it seems unlikely that they would be at fault, and also the problem is worse when shooting into the light and worse again when the light sources are diffused by fog. The effect combines with what are probably condensation streaks on some of the shots in fog. Does this mean it's flare rather than light leaks? I should add that all these shots are taken at night with exposures up to 30 minutes. Any ideas? I would be grateful if there's something definitie I could do about this. Thanks.

11-Feb-2004, 06:53
While there's a chance that the film holders are the problem, I would have to say that if you're getting 'light leaks' on film shot in all your holders, then it's probably the camera. If it's only on one or two sheets, then perhaps the holders are the problem.

I would suggest that a careful inspection of the camera is in order. Take the camera into your darkroom, or if that's not an option, a dark room (!). Remove the lens board and shine a flashlight into the camera. Then look around the outside of the camera for any signs of light. Note that you'll have to move the flashlight into all sorts of interesting angles, and you'll have to move your head around a lot too, since a light leak may occur only at a particular angle.

If you find any light leaks, then you may have found your culprit. I say 'may', because there could be more than one. Repair any light leaks as best you can - black electricians tape works well, as does gaffer tape.

Extend the bellows as far as you can, checking for pin holes in the bellows using the flashlight. If you can remove your camera back, do that, replace the lens board with a lens, and then check the front of the camera. I had serious light leaks around the front of my camera that was fogging my film, so make sure you do this check.

In other words, check everything you can.

Once you've done that, you need to take some test shots to check for leaks. Instead of burning film, use paper. Take a sheet of paper and expose it to white light under the enlarger until, when developed, you just start to get density - in other words, take the paper just over the exposure threshold. Then, carefully cut the paper into film-sized pieces that will fit into a film holder.

Take your camera outside, or under a very bright light, and insert the film holder. Making sure the shutter is closed, pull the darkslide, and move the camera around, making sure that light hits every part of the camera. You can even use a flashlight to shine light into the various nooks and crannies. Re-insert the darkslide, and develop the paper. If the paper is anything other than just barely off-white, then you have a light leak.

If you have leaks, repeat the process again.

If you've iterated a few times and you still have light leaks, then there may be a problem with your film holder(s). Or, there may be a problem with how the film holder seats in the back. Stick with one holder to minimize the number of variables - or, better still, try and borrow a holder from a fellow photographer that is known to be light tight. If you still have light leaks with this holder, then it's something to do with the camera, most likely how the film holder sits in the back.

Is your camera a wooden camera? If so, you may have an out-of-square problem witht the back - perhaps the back isn't flat. Does the film holder sit perfectly flat when inserted into the back?

Unfortunately, finding light leaks is a lot like being a detective. Poor pay and lots of time consuming frustrating work. However, when you *do* solve the problem, it sure feels good.

You could also try covering the camera with your darkcloth during the exposure. Doing a night shot, it should be pretty easy to keep the camera dark using your dark cloth. If you still get light leaks, then you may very well be looking at a flare problem. Not too much you can do about that, other than shielding the lens from any extraneous light sources.

Hope that helps. Good luck!

David Richhart
11-Feb-2004, 07:37
Gee whiz Ken... you didn't leave much room for the rest of us to answer so we can look smart ...

Rich Long
11-Feb-2004, 11:15
Well, Jon, it could be.... Oh, I see Ken covered that.

Then there's always the.... yeah, he explained that also.

Well, as a last resort you can always.... oh, wait. Ken's described that one, too.

Never mind. I'll go back to lurking now.

Ole Tjugen
12-Feb-2004, 00:46
Everything is covered - except the one that took me two years and countless ruined negatives to find: Around the back of my camera, under hte groundglass, where the holder slides in, there are strips of black felt along three sides. One of these was missing. I finally figured it out when I realised that the fog was always parallell to the long side of the film, and never occurred when shooting into the sun...

jon walker
12-Feb-2004, 11:18
Thanks guys. I take it that the specific pattern of contamination here (diffuse bands parallel to, but not necessarily extending all the way to, the film edge) is not ringing any bells then?

Brian Ellis
12-Feb-2004, 18:29
This is a real long shot but did you by chance recently remove a normal bellows and replace it with a bag bellows or vice versa? I recently had a massive light leak problem on a three month old Ebony camera and traced it down to not properly securing the normal bellows at the back of the camera when I put it back on after using the bag bellows. I mention this only because the problem manifested itself as straight diffuse lines that were parallel to the film edges, kind of like what it sounds like you're getting.

Even if you haven't replaced the bellows lately, you might check how it is attached to the back of the camera. I'd hazard a guess that the problem lies with something that has a straight edge and that isn't being properly attached to the camera so that light is getting through at an edge - maybe the bellows, maybe a lens board, maybe something else. When I've had light leaks from pin holes and also from a small hole in a lens board the problem has manifested itself as something that looked like a lot of overall flare, not straight lines. But then I haven't had every possible light leak, it just seems that way sometimes.

Doug Pollock
12-Feb-2004, 19:16
If an international/graflok back is removed from the backplate of some cameras that allow you to remove and rotate that backplate, and that backplate is rotated 180 degrees, and the international/graflok back is replace in its original position, then the film holders will be held up slightly by a ridge which is designed to stop the film holder from being inserted too far. This results in ruinous leaks in almost any light conditions which are located parallel to the film edge but about 3/8 inch away.

13-Feb-2004, 08:57
All I can say is that it doesnt sound like any film holder leak that I've had, and Doug or Brian are probably right. The leaks I've seen due to leaky holders are usually streaks or comet-like marks coming in from the film edge at various angles, not parallel.