Strange change in exposure on half of negative

I have this issue with Summarit-M 35 2.5 and Jupiter-12. The are very different lenses for interior part before shutter.
 
rick oleson said:
Your mention of bright sun strikes a note that had been occurring to me: could it be that the lighter areas are seeing a reflection of stray sunlight from the floor of the interior between the lens and the shutter? How well is that area baffled/flocked? The darker band might be the part that's properly exposed, protected from the reflection by structure below the negative frame in the camera (this band is at the top of the image but the bottom of the film negative in the camera)
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I've seen this phenomenon on occasion as well, and this is what I always figured was the cause. On my screwmounts at least there's a little step in the metal with a curved edge. If it's not perfectly dull (and few of them are at this point), it could reflect bright light up onto the film. The edge of the frame above it may shade the reflection from the edge of the film.
 
If it is determined not to be a developer volume problem, the light shield around the shutter has failed. Second clue will be if the darkness goes between frames.

You need professional repair
 
No doubt. I just want to be prepared financially. Two shutter curtains are much more expensive than light shield, I guess.
 
Sorry I never followed this up! In the end the 'CLA' was basically useless (I still swear they didn't even open it up) and I ended up selling the camera with a full disclosure about the line thing.

Sorry I couldn't be more help
 
Ko.Fe. said:
No doubt. I just want to be prepared financially. Two shutter curtains are much more expensive than light shield, I guess.
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Doesn't look like curtains to me.... I'd guess either light shields or reflections.
 
Are they light shields or designed to protect the shutter curtains/drums?

My Leica IIIa doesn't have the shields and doesn't leak any light.

I just checked my IIIf and they have the shields but there seems to be a large gap to allow for the channel on the shutter where the two curtains meet and move when the shutter is fired. If they are light shields wouldn't the gap to allow for this let in light?

My M4-P has shields but they look to me like their purpose is to protect the shutter drums.

Should there be shields installed? To me they look like they are installed to protect the shutter. Maybe added on units after my IIIa. Doesn't look like shields installed on this IIIa.
 
More comments I read, more uncertainty comes. I have very simple FED-2 with nothing but metal shields, for shutter curtains. No light leaks, no reflections.
If it is worn out something, curtain, seal - why certified and most experienced technician was not able to see it? I have my M4-2 CLA'd just recently. This particular problem started to show up few months before CLA, but after CLA it is worse.
 
The location rules out a curtain as the problem. I've looked carefully at my negatives and where I've had a similar situation it is almost certainly not a question of underexposure along the very edge, but rather overexposure just above it, with a hard delineation of the change toward the top edge of the photo and a soft, gradual delineation toward the center. This strongly suggests stray light reflected onto the negative, with the portion that would fall along the top edge of the photo being shielded by something.

Whether the light is coming from the front and being reflected by a not-fully-dulled piece of metal (as I believe), or possibly from the bottom via a light leak along the edge of the bottom plate, I can't say for sure. Direct sunlight does seem to be a factor. One might try taping up the edge of the bottom plate to see if it made a difference.
 
Bill Clark said:
Are they light shields or designed to protect the shutter curtains/drums?

My Leica IIIa doesn't have the shields and doesn't leak any light.

I just checked my IIIf and they have the shields but there seems to be a large gap to allow for the channel on the shutter where the two curtains meet and move when the shutter is fired. If they are light shields wouldn't the gap to allow for this let in light?

My M4-P has shields but they look to me like their purpose is to protect the shutter drums.

Should there be shields installed? To me they look like they are installed to protect the shutter. Maybe added on units after my IIIa. Doesn't look like shields installed on this IIIa.
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Yes, they are light shields. A IIIa (and a similar early Canon) will leak pretty easily if you change lenses outdoors, so these were added in the IIIC model. They aren't air tight, they just make the light bounce around a few more corners before it can reach the film. Generally they are pretty effective, though changing lenses on a rangefinder is still a bit less secure than on an SLR. I can't think of any way in which they can deteriorate, they are just black metal panels standing in place, nothing touches them in normal operation.
 
Finally, I was able to see it.
Pointing flashlight to the lens or to the shutter directly and looking from behind was never showing it. Few minutes ago I decided to get my eye close to the shutter (camera back) and look down. Vuala, huge light leak. I cocked the shutter and it is not curtains. The light leak doesn't change, it stays. And only on the bottom, this is were I have this horizontal light leak. With smaller aperture it is less and less light, less it is going to be as well.
 
Had the same problem. Seems to have been cured by:

1. replacing the light baffles/shields (DAG calls them that way) just below the curtain

2. replacing light baffles in between the lens mount

3. never changing lenses in bright sunlight
 
This is definitely NOT caused by too little developer in the tank. When there is not enough developer, you get a vaguely similar effect but far less clearly defined because the developer moves around in the tank. Insufficient developer results in a softer, not so clearly defined line.
 
Ko.Fe. said:
Finally, I was able to see it.
Pointing flashlight to the lens or to the shutter directly and looking from behind was never showing it. Few minutes ago I decided to get my eye close to the shutter (camera back) and look down. Vuala, huge light leak. I cocked the shutter and it is not curtains. The light leak doesn't change, it stays. And only on the bottom, this is were I have this horizontal light leak. With smaller aperture it is less and less light, less it is going to be as well.
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Glad you found it. Just so I understand, you're looking down into the film gate and seeing light leaking in under the curtain, correct? And this light appears to be coming from the lens itself, not via a leak in the bottom plate?
 
Lens on or off, doesn't matter. Hinged back door needs to be off. Flashlight upfront, through the lens or into the lens mount. Looking at the camera back. Turning camera (flashlight is following) to see the space between curtain and camera film channel. To see the lower part of the film frame. Light leak becomes visible right away. Turning it to see same space but on the top and left-right doesn't show any light leaks.

Now... I took my M3 and FED-2 for the same test. M3 has it as well, maybe slightly less. FED-2 is shining light on the bottom, corners and top. But M3 and FED-2 are leaks free...
 
Interesting. I wonder if the light getting to the film via the path you describe is also determined in whole or in part by the design of the lens. I know the J-12 has a huge rear element that could easily throw light all over the place, especially above and below the frame; I don't have a Summarit-M 35/2.5 to compare it to. I have to go back and look to see what lenses I was using when I saw the same sort of leak. What lenses do you use on the FED and the M3?
 
FED-2 was shining it without lens. I din't put lens on M3, either.
M4-2 was tested without lens and with I-22.
All three cameras have it on the bottom part of the film frame.
 
I understand, but when it appears on the film, the light has had to pass through a lens. I'm curious if some lenses might be more prone to causing it than others depending on the distance of the last element from the film gate.
 
That could be possible; a J-12 or Biogon with the rear element close to the shutter will be spreading the light in a very broad cone, which might find its way through a baffle more easily than the narrower cone coming from a normal lens. A tele, on the other hand, might cover a wider area than is needed for the 35mm format - this would result in light striking the sides and floor of the area behind the lens mount, which might then reflect off of the walls and find its way around the baffles. Worst case of course is when the lens is off.
 
The problem is progressing. It was present before it left for CLA. On ten rolls I took in Moscow it was on couple of frames. After CLA it is on multiple frames at every roll.
My most used lens on M4-2 is Summarit-M with very small optical part and it is not protruding anywhere. J-12 was on camera only once after CLA and here is no difference how flare, leak looks between J-12 and Summarit-M 35.

Summarit 35 in 2016 summer, before CLA:

29860759676_1e369e4800_o.jpg


Very first roll after CLA in 2017 with J-12:

M4-2_J12_RPX400hcB_AGFA8x10BroviraII_AristaLith_17952.JPG
 
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