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Cleaning & Repairs
Fixing Light Leaks

Is all your darkness spilling out? You may need to revitalize the light seals and do some upgrades to ensure you have a light proof enclosure that will hold all the darkness inside. There are a series of black paper baffles which over time may have been displaced or have creased and are ineffective. As well, the Yak hair yarn use against the body is probably not doing a very good job either.



Depending on which year Kiev you have there may be subtle different applications of light baffles. The main top casting will have to come off to reveal the following. See: The Basics - Top Casting Removal. Again, depending on year you may find a paper baffle shown by Yellow Arrow. Note the little bit of Yak hair yarn just below the viewfinder window indicated by Blue Arrow.


I usually replace this small paper baffle with something a little more substantial. Black paper or plastic bag material from photographic paper is useful for this application. I glue it down or use tape along the edge to make sure it seals.


To replace the light baffle inside the rangefinder window you must remove the rangefinder glass. Remove the four screws indicated by Yellow Arrows. To get to the one screw on the right side lift off the exposure indicator gear circled in Red.


To get access to the rangefinder window baffle you can sneak the rangefinder glass out as shown above.


The rangefinder window light baffle is shown above with a few assemblies moved out of the way to make it clear. Check the condition of this paper baffle, it may need replacement. 


Here's a couple views to show the black plastic material I use. It is cut a little larger than the original paper and has a couple folds and cuts to help it lay down against adjacent assemblies.


Other areas to have a look at, does anything interfere with the back film plane casting from seating down flush against the camera body casting? Here we see the shutter delay timing assembly interfering enough to cause a gap. By the way, how flush is the surface of the back film plane casting and the mating camera body casting surfaces? If I at the very least sand the back film plane casting with 400 grit sand paper on a smooth glass surface. If I have the shutter removed, I do the same to the mating camera body casting surface as well. Note, that if you do anything to these surfaces you are changing the film plane to lens flange distance and will have to be adjusted.


This area is always a problem and is the number one place for light to show on your negative radiating from the sprocket on your negative.


Remove the film plane back casting and check, there is a thin flat metal washer acting as a light baffle as shown, and depending on year there may be an extra light baffle bent into a funky stepped shape just behind that. These may be bent and probably need some extra help.


To augment the feeble light baffle at this location add a piece of closed cell foam as show by Red Arrow. As well, depending on the gap size between the shutter assembly and the body casting you may need some light sealing as indicated by Yellow Arrow as well.


The original Yak hair twine that was used for a light seal at the location shown by Yellow Line was an interesting application but it probably is the main source of light leaks. We can do better with modern materials that perform better.


I replace the light seals with more modern synthetic materials. This urethane foam made by Rogers Corporation under the Poron product name has an adhesive back and comes in many thicknesses, densities and cell structures. The top-most one I find most appropriate for replacing light seals. Samples may be acquired from Rogers that will last a lifetime.


More information on Poron Urethane Foam can be found on Rogers Corporation web site.



June 05, 2006