Shutter issues with the M3; Tell me if I’m being picky

[Erwin Park]

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Okay so, a month ago, when I had my M3 serviced (again), I wrote the following post: 

So the 2nd and 3rd issues (since they are owing to the same reason) I mentioned in the previous post still remains even after the service this time round.

The photo I uploaded here is one of the 76 frames that I only took a bright sunny blue sky to test the performance of the shutter. (I’ve used two rolls only for this, they look practically almost the same so I only present one here). The settings were f/8 and 1/1000s (ISO 400 film), and the lens was Summicron 50 mm. We can assume that vignetting can be ruled out.

You can see the left upper side of the frame is much darker than the other part of the frame. The right side of the frame is also slighted darker probably because of the same shutter issue, but it is not as severe, so let’s ignore that for now.

What I wanna ask you is, if you were me, would you just ignore this shading issue and just use the camera or try your absolute best to fix this?

Somewhere in RangefinderForum, I read someone saying “even at Leica, the tolerance limit for the 1/1000 shutter speed is 20% as it is prone to be out of calibration”. (Link: https://rangefinderforum.com/threads/leica-m-1-1000-uneven-shutter-issues.79230/) Also, the experiment was conducted under a very extreme conditions, so I presume in practice it won’t be as noticeable. Additionally, I’ve seen many people saying that even for newer Leica M film bodies, the 1/1000 speed tends to be an issue quite frequently.

Considering all this, does this seem to be an acceptable condition that you’d use this camera after biting the bullet, or would you try your absolute best to fix this issue by trying other servicemen as many of you suggested?

I’d like to see what you guys think. Thank you.

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[jgeenen]

I see the darker shades, but they are not aligned parallel with the edges. Instead - albeit not perfectly centered - you can see a central somewhat  brighter spot. So I assume the lighting differences are caused by normal light scattering in the sky and not by uneven shutter movement. A correct test should be done against an evenly lit monochromatic matte surface, not against the sky. It is merely impossible to get even lighting in a blue sky (even fog or cuds do have gradients in brightness most of the time).

if you can‘t observe the shading under real conditions, leave it as it.

[Erwin Park]

I understand this might be because of the light scattering, like you mentioned. However, the same shading pattern has been observed in different situations as well, so that's how I concluded this is owing to the shutter issue.

and for the thought, yes I guess I'll just have to try not to use 1/1000 for landscapes.

[Erwin Park]

I also should add that my serviceman said the camera’s mechanism is worn out and it is old, so this issue cannot be fixed completely even if I replaced the shutter curtain to a new one. He said this is the best condition he could put the camera in. But, that’s just what he claims, so I don’t know whether that is actually true or there’s another way.

[jgeenen]

vor 31 Minuten schrieb Erwin Park:

However, the same shading pattern has been observed in different situations as well,

I assume, different root causes are overlapping and form the visible effect altogether:

• a worn shutter, creating some sort of uneven exposure (haven’t noticed the banding effects seen in your first samples)
• light scattering
• light falloff (even at f/8 light falloff is not 0)

All of this can add up to create a visible effect. Remember, at a 1/1000s, the exposure slit of the focal plane shutter is just 3mm wide and a +/- of a fraction of a mm can easily pile up to 1/3 stop exposure difference. At 1/500 the same wobble would create only barely visible 1/6 stop variance. Best to use the camera at 1/500 under critical situations.

[250swb]

It wouldn't be unusual to limit yourself to 1/500th top speed, lots of people do it on any older camera because many types of mechanical shutter become inaccurate at their extreme ranges. But at the same time you've done the test shooting a blue sky, and despite it looking to the eye an even blue the brightness and blueness of the sky does vary quite a lot and maybe you are just seeing something you expect to see or are suspicious of and are making two and two equal five?

[Erwin Park]

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16 minutes ago, 250swb said:

It wouldn't be unusual to limit yourself to 1/500th top speed, lots of people do it on any older camera because many types of mechanical shutter become inaccurate at their extreme ranges. But at the same time you've done the test shooting a blue sky, and despite it looking to the eye an even blue the brightness and blueness of the sky does vary quite a lot and maybe you are just seeing something you expect to see or are suspicious of and are making two and two equal five?

I've used two rolls (hence 76 frames) and one roll was used when the sky was cloudy as you can see in this image attached to this reply. I picked one where this particular issue is prominently exhibited. Here, the setting was f/16 and 1/1000.

1 hour ago, jgeenen said:

light falloff (even at f/8 light falloff is not 0)

You can also see the faint streaks from the left side as well, which was a problem as well. This issue has remarkably improved as the shutter curtains were cleaned.

When the sky was more gloomy, the issue appeared more clearly here.

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[TomB_tx]

Even exposure side-to-side at high shutter speed is hard to achieve, which is why Leitz had to modify the shutter on the IIIa - the first Leica to offer 1/1000 speed. As the curtains move across the frame their speed is not constant, so for fast speeds the slit width between the curtains must change as they move across the frame in order to keep the exposure constant. I gave my 1955 M3 to my son last year, and when processing film for him recently noticed side-to-side shading very similar to the above post, and he verified he had used 1/1000 speed on some shots. My advice to him was to try to stay 1/250 maximum unless he wanted to have the camera rebuilt - not just a CLA, as worn parts may need to be replaced to fully cure the issue. Many techs who do a "CLA" only don't fully disassemble the camera to examine the parts, etc. - which is what a full service (or historic CLA) would do. Maybe 10 years ago I sent a basic Pentax S1a to a Pentax tech and he sent a picture of it fully disassembled and spread out on the workbench, which is how he did a service. (It does now work like new.)

I'm sending my 1929 1A to DAG for a full service for that reason.

[jerzy]

picture on film stripe is flipped, horizontaly and verticaly. So the darker part of the picture is when shutter starts to run, Slit width is too narrow there, therefore underexposed. During the run the opening curtain becomes too fast (or closing curtain too slow). Unless the shutter is really heavily worn I believe that it can be adjusted, at least a bit better. Firstly  the release moment of closing curtain shall be delayed a bit and then the tension of the spring of closing curtain  increased.  It is nothing what you can do at home, you would need to have testing device that shows you slit width accros the frame.

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