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light leak

S

sixbysix

New Member
I just returned an original 12 back to Adorama because it fogged a roll of film. I exchanged it for an A12 back, but before I ruin another roll of film can anyone describe to me in detail how to check for light leaks in the back?

Thanks
 
I wonder too if there is a way to check for leaks without shooting a roll of film.

I haven't been able to think of one so I've just run a roll of b/w film through each newly acquired back on a sunny day. (as I process these myself and don't invest too much effort into the images - hence a lot of pictures of my back yard - the cost's not too high considering the typical investment in the back.)
 
Use cheap film. I give the magazine plenty of exposure to direct sunlight, with the darkslide in place of course, then fit the magazine to the camera, remove the darkslide, and again give it plenty of exposure to direct sunlight. I do this a few times in the course of shooting the test roll. If it comes through that test it's probably going to reliably keep out the unwanted light.
 
Okay, thanks for the advice, guys. I heard there was a way to check with a flashlight -- has anyone heard of that?
 
Ugh. Tried to run a test roll through the new A12 back and the film wouldn't advance, so it's back (no pun intended) to Adorama. I've wasted two rolls of film (and the processing fee on one) on two backs already. I should have tested the the advance before I loaded it!
 
The light seal is in most cases the cause of the trouble. Although the price for original seals has gone up quite a bit recently get a couple of these seals and replace any dubious seals.
Replacing the seals every 4-5 years is the best guarantee against light leaks.
I check the operation of the seal by using a desklamp to shine into the frame part of the back with the darkslide removed.
Hold the darkslide at a 90 degree angle with the back just over the opening for the darkslide and look for any signs of light emitting from the opening.

The best method method to check the light seal is to remove the frame plate from the back and see how the seals look.
If the foam is not firm but is starting to fall apart fit a new seal. Do not forget the best light seal can be ruined by warped or otherwise damaged darkslides.
Not to replace those is false economy, the new seal will be damaged sooner tham you think.

Anybody who is able to hold a small screwdriver without danger to himself or his environment should be able to fit new seals in a film back.

I will post a step by step description to replace seals if readers are interested.
 
It starts with the way the demonstrator holds the screwdriver etc.

Secondly I do not advise the use of home made foam strips for lighttraps as long as original parts are available.
 
i though he was using an original foam replacement?
but appart from that (and the way he handles his tools), is the step by step working method correct?
or does he do things that can harm the back or a better approach?

maarten.
 
Original foams are black and are fitted with a thin metal strip that is modelled to give the correct pressure.
The metal strip makes fitting easier as well.

The small screws are often quite strongly tensioned.
To release those the screwdriver needs to be pressed down tightly to avoid damage to the screwshead.

To carry out a repair job succesfully without causing damage requires a certain amount of experience.
 
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