Light leak - please help diagnose

[Eric Wagner]

I agree with DJ and Tracy. If you are patient and persistent, you ought to be able to spot the leak in the darkroom. If not, then you will have to test with film. Set the camera up in your backyard, pull the darkslide, wait five minutes and then replace the slide. Do the same with another film, except this time make an exposure. Then do the same with your dark cloth wrapped around the rear standard and the rear 2/3 of the bellows, and another with you dark cloth wrapped around the front standard (make a tunnel in front of the lens) and the front 2/3 of the bellows. By studying the developed films you ought to be able to zero in on where the leak is coming from.

[John Cook]

Several things can cause this. And I don’t know all your circumstances.

But a common problem I and my fellow students had as LF beginners in school looked exactly like this and was caused by a very small light leak between the film holder and the camera back.

The light leak, in turn, was caused by the holder slightly separating from the camera back while tugging on a stubborn slide.

Three cures. First, wax the holder slides with automobile wax. After years of experimentation, I have come to prefer Meguiar’s High Tech Wax 26.

Second, keep the focus cloth draped over the top of the camera in bright sun for extra protection.

Third, while removing (and inserting) the dark slide with the right hand, get in the habit of squeezing the ground glass frame and holder against the camera back with the left hand.

[bob moulton]

Guy;

Another testing possibility: Set camera up for image and then encircle bellows from lens standard to film plane in your darkcloth or something large enough and preferably dark enough to cover the whole bellows. Make your images. Then duplicate that procedure without the dark cloth wrap on another set of images. If the first two are ok and the latter are not at least you have a suspicion it is the bellows.

Another thought: How new are your film holders and dark slides? It is possible though I would not say probable that the slides leak light. Still another possibility. Check the room where you load film. (I assume you aren't using ready/quickloads.) If light gets in there could your problem.

If all your negs were loaded at the same time that solution seems less possible, but hey!

You might open your film box, set a couple of sheets out, let them set in the dark for about the time it would take you to unload one -three holders, and then process those films together to see if any problems appear.

good luck, Bob

[David G. Gagnon]

Guy,

As in your previous qustion posted about this problem, I'm saying that this is a double image being produced by a void around the lens somewhere, even more so now that I've seen it. Have you tried a different lens/lensboard? Try that, and I'll bet that it will not happen.

DG

[Richard Fenner]

Further to John's comments, I once had a series of similar patterns on my slides, and with a polaroid back, eventually realised I could only insert the holder into one side of the back, not both sides - it went into both, but was very slightly loose on one, and that's the side that always produced the pattern.

[Scott Walton]

I was getting the same fogging about a year or so ago. It did turn out that I had some corners that were broken getting light in when the bellows was out and the sun hit it just right. In the photo, nice shot BTW, the sun is coming in from your right/rear so I would look for folds towards the rear of the bellows. In a darkened room, use a flash light on the outside of the bellows and looking inside (or visa versa if that is easier), move the flash light in every angle. At first, I thought mine came from not correctly seating my holders but it turned out to be the bellows. Camera Bellows (in the UK) is the place to get a new bellows. They are excellent craftsmen, very fast and a beautiful product! One other thing, check to make sure your back has good tension holding the back tight...

[Ole Tjugen]

I had a similar light leak - always parallel to the long side of the film. I eventually traced it to a strip of velvet which was missing from one side of the camera back. It originally had velvet light traps around three sides, but one had got lost somehow.

[Guy Tal]

Thanks everyone. I found and fixed the problem! I removed the bellowd and found that the leather separated slightly from the plastic frame near one corner. I haven't noticed it with my other lenses since the bellows wasn't fully stretched (as it was with the 300). A little super glue fixed it right up and I just got a couple of clean chromes back from the lab.

Thanks for your help!
Guy