Light leak on Yashica FX-3 Super, even after new seals

[Vonder]

Ok, so, here is an example. I replaced the light seals around the film chamber to correct a light leak, but the light leak is still there. Any suggestions on where else to look? Thanks! Note, only 2 frames out of 36 had the issue. One "test frame" was shot with the camera back facing the bright sun, and no leak showed up. In this picture the sun is in front of the camera. On the other leaked image, it was on the side.


Light Leak by Howling Wolf, on Flickr

 

[Neil Grant]

...that's a nasty looking one. Is it always the same or do other streaks occur? Poorly fitting back? Cracked top or bottom plate?

 

[Kino]

What sort of shutter does this camera have and how does it move? Is it a curtain or a segmented metal or ...?

I can't imagine how this leak occurred via a hole in the body, but maybe one of the shutter elements has a defect that is exposed depending upon shutter speed?

 

[Theo Sulphate]

Due to the geometry of the leak, which is so precisely defined, it doesn't seem that it would be from a simple gap around the camera back. I think the leak may be always present when the camera is oriented a certain way, but strikes the film only at the moment of exposure.

As Kino wrote, check the shutter.

If possible, hold the shutter open at B or T and with the back open move a strong flashlight around the camera as you look from the back. Try different speeds, as Kino suggested.

 

[ic-racer]

One could tell if the leak were from the shutter if the negative were examined. Could we see the negative?

 

[shutterfinger]

What sort of shutter does this camera have and how does it move? Is it a curtain or a segmented metal or ...?

Take a look at page 2 of this manual http://www.cameramanuals.org/yashica_pdf/yashica_fx-3_short.pdf , its a vertical travel segmented shutter.
Cock the shutter, in total darkness with the mirror up shine a bright light in through the lens opening with the back open. Observe the shutter from the rear of the camera. Release the shutter and check the second curtain in the same manner. Any hint of light (anything other than black) is a light leak.
What is the condition of the foam around the pentaprism where the mirror rest during exposure? Weak/deteriorated - replace it.
Many/most cameras the mirror can be lifted up from the down position, if not trip the shutter on a slow speed with the lens removed and hold it up while checking and cocking the shutter.

 

[Vonder]

Thanks for all the suggestions!

Well. I shot another test roll after replacing the foam around the mirror area. No luck. Oddly though, the very worst image was one where I mounted the camera on a tripod and used flash which was bounced it off a low white ceiling. That photo has a bolt of lightning across it like you wouldn't believe! So, I'm thinking maybe it's something on top of the camera. Weird. I may have to take it apart and look inside.

 

[MattKing]

If the flash was mounted in a camera top hotshoe it may have flexed the top of the camera.

 

[Theo Sulphate]

One could tell if the leak were from the shutter if the negative were examined. Could we see the negative?

Yes, please show or describe the negative. Is the light leak only in the image area or does it extend to the rebate area around the sprocket holes?

If you get to the point of taking the top plate off, check the foam around the prism as shutterfinger suggested.

 

[kmg1974]

I would propose the following test (with a cheap b/w film)
place the camera on tripod, with lens cap. Hold a very strong light at different angles while taking one picture (make a diagram so you know exactly which picture has the light arranged where). then you can repeat it with a lens.

the strange discharge when you used the flash could suggest that you have an electric discharge from the flash unit through the film...
curious and hope you get it fixed