Contax 137 MD light leak (SOLVED)

[truls]

I have two of these, both leaking light. The seals are replaced, and I have done this lots of times. First seals from Aki Asahi - leaking. Replaced them with my own more generous cutted seals - also leaking. Here image samples:





Could there be leaking from another location? Prism housing or something?

[Stephen]

No direct experience of the Contax, but looked up the kit etc., and photos of the back. The marks suggest the camera ends, either the hinge or the catch end, and spread along the frame evenly, so a small slit is still open at one end or the other. The prism etc can be discounted, but the shutter cannot, it may be slitting open as wind on is occurring.

You can test for this by putting a lens cap on after each shot.

But it is far more likely to be the catch end of the back leaving a gap due to the camera back being slightly bent. If it's not a good fit it may leave the catch unable to pull the back tightly in to the light traps.
So check the back and gently bend to a good tight fit, and check the catch is pulling on it. Really this should be done before fitting the light traps in place, to be able to see if the gaps left are even.

Foam kits relieve making seals, but personally I prefer black cord or Wool tightly wound into a cord. Black felt can be used where "plush velvet" is used on most cameras.

A remoter possibility is the door hinge has moved, often riveted on, but maybe this one has screws and they have come loose, allowing a slit at the hinge end, worth checking.

Stephen.

[Stephen]

Are these home processed? It could be the film cassette leaks light, or the film tank on some makes can leak, especially daylight loaders!!! Never trust the tanks, load in the dark.
If it is an old cassette and re-loaded with film, the plush may be tired or even missing inside the cassette body.
If it is a type that "pops" the end off, check the plush is still there.

Don't forget the remote chance that if processed by a shop, the processor has faulty machinery!!!!

Stephen.

[Stephen]

I have spoken to a friend who services cameras, and his bet is a slightly distorted back, added to the hinge, which is a removable type, which always have more play in the pins.
Contax and Yashica are prone to leaks due to the "loose" floating design of the back, which rely on the seal to position itself.
Check the back is not "askew" i.e., the ends are actually in line and parallel to each other, with no twist at all, then very gently bend the whole back till it sits level at all points.

If all fails , then use black adhesive tape along the joints on the outside, gradually removing bits till the fault comes back, and you then know exactly which seal is still giving trouble.

Stephen.

[truls]

Thanks for your help Stephen!
The film, Fomapan in facory made cassette, I only used half of the film. The other half in another camera, ruling out darkroom bag or developing error. The other half film came out perfect, in another camera of course.

I cannot put a lens cap on, it has motor drive, too fast for attaching the lens cap between shots. I also think the fault is in the back somewhere, as you suggest. So I will work from what you suggest. Will come back with more information later, hopefully I can fix this. It is a good camera and fast shooter on the go.

[truls]

Small update, light leak solved.

It seems the door and hinge seals are critical in what way it is fitted. The material used can also play a role. I used a more opaque type light seal, and made a cut to fit end to end at the hinge. Also at the door I made a slightly bigger seal, the opaque type.