Mysterious M5 Light Leak

[StephenH]

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I recently acquired a Three Lug Chrome M5 in what I would call "user" condition and have been generally happy with it so far, although the infinity focus seems to be off --which may or not be relevant here.   On the first few rolls I noticed in the lower left hand corner a conical shape (see examples below from a more recent roll) on only a few exposures per roll.    The apparent fogging only appears within the frame of the picture and not in the sprocket area which would seem to  rule out a leak through the back.  Nevertheless, since the lower left in the negative would be at the upper right in the camera, I suspected that the upper right hand corner of the back door may have had a  leak since it roughly corresponds to the affected area of the film which might might be fogging  while it "dwells" in that position before being moved into the film gate to be exposed.  My M5 has a strip of mohair along the right side of the door which may or may not be original--i'm sure many of you can tell me if it is.  Original or not, it seems to have been overly compressed in the upper right hand corner due to its proximity to the hinge.  I added some foam rubber strips to that corner in an attempt to fix the leak, if it was a leak at all.  Since then,  perhaps coincidentally, the frequency of this phenomena has decreased.  On my most recent roll, only these two frames are affected.  They are adjacent to one another.  In the frame with the church steeple (later exposure),  the sun was in front of me.  In the other, it was behind me.  While I did change lenses between the first and second exposures, i don't think that was a factor because the exact same defect has appeared when I hadn't changed lenses.  Also the defect has appeared in both horizontally and vertically held camera positions--and it has a consistent shape and position in the image.   I have researched this on various forums and one fellow with a similar problem was advised that this was caused by leak from the rangefinder window which the forum member claimed was essentially a latent defect in the camera.  I found that hard to believe due to the fact that its very sporadic and appears in vertical orientations when the view finder window would be far less susceptible to sun light from above.  Any thoughts? 

 

 

 

 

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[radialMelt]

This type of light leak seems to plague the M5. From my research it would seem that in most cases the source of the leak is failing light seals in the rangefinder window to viewfinder path. Sometimes it is easy to identify. In a darkened room, open up the shutter (SS = B, shutter depressed, with a locking cable ideally) and shine a bright light into the rangefinder illumination window. Take a look around inside the film path and chamber while you're doing this. Pay particular attention to the upper right hand corner of the chamber (when viewed from the back of the camera that is). Sometimes there is a little tiny gap where the light finds its way in. 

Not sure if you can see the images in this thread on RFF, but there's a good illustration of what I'm referring to: https://www.rangefinderforum.com/forums/showpost.php?p=2962204&postcount=35

Good luck!

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[StephenH]

24 minutes ago, radialMelt said:

This type of light leak seems to plague the M5. From my research it would seem that in most cases the source of the leak is failing light seals in the rangefinder window to viewfinder path. Sometimes it is easy to identify. In a darkened room, open up the shutter (SS = B, shutter depressed, with a locking cable ideally) and shine a bright light into the rangefinder illumination window. Take a look around inside the film path and chamber while you're doing this. Pay particular attention to the upper right hand corner of the chamber (when viewed from the back of the camera that is). Sometimes there is a little tiny gap where the light finds its way in. 

Not sure if you can see the images in this thread on RFF, but there's a good illustration of what I'm referring to: https://www.rangefinderforum.com/forums/showpost.php?p=2962204&postcount=35

Good luck!

Thank you--that seems to be consistent with what I've been reading but I have been unable to confirm with the flash light test, most likely because i'm not that dexterous.  What puzzles me, though, is why it so sporadic and unrelated to camera orientation.  Perhaps i'm afraid that if it is what you suggest, it will be unfixable.  

[radialMelt]

Just now, StephenH said:

Thank you--that seems to be consistent with what I've been reading but I have been unable to confirm with the flash light test, most likely because i'm not that dexterous.  What puzzles me, though, is why it so sporadic and unrelated to camera orientation.  Perhaps i'm afraid that if it is what you suggest, it will be unfixable.  

It's not inconceivable that the light has to hit the rangefinder window at just the right angle to reproduce the problem; there's lots of variables at play here. Meaning perhaps it only happens when the sun is hitting the RF window at precisely the "right" angle to exacerbate the issue. Same thing for your test. Admittedly it can be a challenge to hold the shutter open and shine the flashlight in the right spot whilst manipulating the camera. A simple test, but perhaps not an efficient one, could be to put your finger over the rangefinder window every time you take a shot-- see what happens! 

And worry not, I doubt it is unfixable. If it is indeed a leak like what is suggested in that RFF thread you could always apply some material (be it liquid or otherwise) to the "hole," effectively patching it up. Or you could send it off to DAG and have him replace the seals in the rangefinder light path. Food for thought.