Patch on photos HELP!

[daniel_aj7]

Hi RFFers,

I have been having this problem with my M6 where there is a patch on my photos, in approximately the same place, about the same shape. It appears on about 4 to 5 shots a roll when i shoot at 1600. 1 or 2 or sometimes 0 when i shoot at iso400.
I sent it to Youxin Ye and he said he did not find anything to cause a light leak. But after getting the camera back the symptom is still there. This guy in the other thread with an M6 of a different serial number has the exact same problem:
http://www.rangefinderforum.com/forums/showthread.php?t=94997&page=2

This got me thinking.. How likely is this a light leak? Shouldn't light leaks be random? What are the chances of 2 different cameras having the exact same light leak? Anyone has any idea what this could be?

 

[sevo]

If the pictures are from two different cameras, chances would be small that that is due to a curtain pinhole each both at the same location - but it is far from impossible, as curtain burn holes tend to occur within the central image range, so that there are only maybe 40-50 patches of that size within the likely area.

Still, the more likely explanation is a constructive light leak, as these will always occur in the same location. A likely suspect in M Leicas is the back door, as most users forget about its existence after a while and won't check it for dirt, wear or warping.

 

[nobbylon]

Back door leak, top left, would be my guess. Take the door off and check the ribbon at the top on the camera, sits behind the hinge line is flat and not rucked up in any way. If that's ok, take a test roll at 1600 replicating the conditions. First as is and then same frames with the back taped with black gaffer tape.
My M6ttl had a problem like this. If you use colour film and the leak is orange it's from the back. I think if it's blue it's from the front. Looks very similar shapes to mine.