M3 shutter needs adjustment - need help explaining what’s happening

[AZD]

Ah well, nothing is perfect I guess. Just getting around to developing a few rolls from my recently purchased M3, and I noticed a problem. The negatives all have an underexposed band, 2mm wide, on the far right side - which is the far left side in camera. I opened the back an fired a few shots on B. Sure enough, I can just make out the first shutter curtain slowing down on the last 2mm of its travel. You wouldn’t see it unless you were looking for it.

What is the cause of this? Is it the shutter brake? I don’t know enough about Leica shutters to be certain, but I’d like to describe it to the shop I bought the camera from. Anyhow, let’s call this Problem #1, because…

I also noticed another curtain issue, which I’ll call Problem #2. When the shutter is set to 1 second, I can see the second curtain creep maybe 2mm into the frame on the right side during the mechanical delay, just before it releases to close. Seems to be happening at 1/2 second as well, but it never enters the frame. What is the cause of this?

Other than this, the frames are evenly exposed and speeds seem accurate.

Hopefully these are minor issues that can be worked out easily. I rather like the camera, but I’m also not irrationally attached to it. So, strike #1. On #3 I’ll just go back to my big, heavy Nikons.

 

[shutterfinger]

The M3 uses a horizontal travel focal plane shutter. The shutter consist of 2 curtains. When cocked both curtains are wound on the right side of the frame. When the shutter is tripped the first curtain is released and spring tension in the take up roller pulls the curtain across the frame opening the film plane to light entering through the lens. The second curtain is released by a timing cam based on the speed selected. The 2 curtains form a slit that is swept across the frame at a specified rate. The curtain travel rate and slit widths may vary from manufacturer to manufacturer.
The shutter curtain material may swell with age (rubberized silk) resulting in the curtain becoming too thick for the cavity it fits into. The bearings in the curtain rollers need lubrication to turn smoothly. The tensioning springs in the take up rollers can weaken with age.

The shutter in this camera needs servicing. The exact cause can only be speculated until it has been opened and inspected.

 

[gone]

I bought an M3 from someone years ago that had just been serviced by Youxin Yee for just this problem. I shot a roll of film and there it was again, so I sent it back to Yee. He went back into it for free, since he had just worked on it. Well, it did the same thing when it came back the second time, so I sent it to John at Focal Point Optics. John said the shutter had been way over-tightened and was getting shutter bounce. He did another CLA on it which ran $250 plus shipping both ways, and it worked perfectly for years after that.

I sold the M3 and bought a Bessa R3a after all that

 

[donotpaint]

I had a similar issue with my Fed 3. I noticed that the first curtain stopped a few mm short of the end of the frame. The reason was that the spring that pulled the curtain across was not strong enough to pass the brake latch, therefore causing the shutter to stop early.

I'm not an expert on Leica shutters, but soviet ones were very similar. If, like in soviet cameras, the first curtain is responsible for releasing the second one, you might be able to fix issue #1 by tensioning the first curtain's spring.

Here is the link to my post regarding the Fed 3's shutter issue.

Edit: I just read momus' reply and it might also be possible that the first curtain is bouncing. In that case, my advice to tension the curtain would obviously not apply.

 

[Nicholas Lindan]

My M3 had the same curtain creep on low speeds. Never seemed to be any sort of a problem so I never did anything about it.

 

[AZD]

Thanks for the information. Good to know it’s probably something “normal”. After looking closer I’m pretty sure the first curtain is bouncing. The best option is to have the shop I bought it from address it. They’re a reputable dealer, so shouldn’t be a problem.

In the future I’d like to become more familiar with rangefinder adjustments and repairs just as a matter of self reliance, so to speak. I have completely disassembled - and reassembled(!) - two Synchro Compur shutters, so tiny screws and springs don’t bother me. Maybe I should pick up a FED for practice?

 

[donotpaint]

Maybe I should pick up a FED for practice?

As an owner of multiple Feds, I give this idea two thumbs up!