light leak, or how best to stick my finger in the dike

[Tom Foley]

Hello all,

I'm new here. This is my first post.

I have a tiny light leak sneaking in between the lens board and the lens. It is so small that I cannot see it, but I can locate the area by going into my darkroom and putting a lit flashlight inside the camera. Then I can see clearly.

My question: what is the best way of repairing this? Is there usually a rubber gasket or washer between the lens board and the mounting flange, or is usual to tighten the flange directly up against the lens board? If a gasket is not the solution, I'm thinking of painting the area with an opaque nail polish on the inside of the lens board. Any thoughts.

Tomasino

[James E Galvin]

Paint might get into the threads making it difficult to get the lens off in the future. I would use modeling clay. You might take the lens off and see if there is anything holding the lens or flange clear of the lens board. A small screw on the back of the lens can do this, it is supposed to fit into a little hole in the lens board to prevent the lens rotating. Most people remove the screw. If there is a large gap between the threads on the lens and the hole in the lensboard (the hole is too big) I have stuffed some black shoe lace in.

[Stephane]

I use vulktape for this kind of task (self vulcanizing tape that only "glues" to itself and leaves no residue and is stretchable).

[Gem Singer]

Sounds like the hole in the lens board is either too large, or was not cut to the proper shape.

Also check to see if there is an index pin on the back of the shutter that is interfering with the shutter seating completely. If so, remove it.

You could use some sort of thin washer or gasket to close the gap, providing you have enough thread length on the shutter to work with.

You can use a larger diameter flange. Before you do that, try loosening the present flange and moving it around until it completely blacks the light leak. Then tighten it in that position.

Finally, if nothing else works, find another lens board with the proper size and shape hole.

[jmcd]

It sounds to me, also, as if there is a problem with the mounting that should be mechanically corrected, as Gem suggests.

Is this a lens that screws into a mounting flange? If so, the mounting flange should be screwed snug to the board. There should be a circular ridge on the mounting flange, and the hole in the lensboard should be sized to just accept this ridge: the pair acts as a light trap. Combine this with mounting the flange snug to the board, and there should be no light leak. Then, the lens should thread into the flange.

[Ty G]

I have dealt with that many times. Sometimes the flange just ain't flat, or the wood have a low spot. Two things that work well..... Plumbers putty; easy to use, doesn't hurt wood or metal. OR go to Waly-World and get a sheet of that self adhesive felt (black) and stick it to the back of the flange, then cut the hole out and cut around the flange. Mount it and it will never be seen, and will not hurt the flange.