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Light leak through mount:


hmzimelka

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Hi again.

Today I wanted to try my hand at taking long exposures with an ND 3.0 10 stop filter. 

I used my new Summicron-m 50mm V, and got some light leaks. I tried covering different parts of the lens and camera and noticed an almost complete reduction of it when covering the mount of the lens/camera. 

I then came home and tested some lens and camera combinations with the lens cap on at f/16.

The Summicron-M 50mm was the worst. The Voigtlander Ultron 28mm ASPH and Color-Skopar 21mm f/3.5 were much much better but not free from light leaks either. 

 

Anyone brave enough to try this on their M11 and better yet other cameras too? 😮

 

 

 

First image: Summicron 50mm lens. 15sec exposure at ISO 64 with the lens cap on. No exposure compensation in Lightroom.

Second image: Ultron 28mm ASPH. Same exposure. No exposure compensation in Lightroom.

Third image: Ultron 28mm ASPH. Same exposure. A +4 exposure compensation in Lightroom.

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I experienced something similar with my M10 monochrom.  This is a long exposure with 10- and 3- stop stacked filters attached to a 21 SEM with the hood attached.  I'd attributed it to the filters being stacked as this did not happen when using only one.  I never would have thought of light leaking through the mount.  You may be on to something though.  

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It's a longstanding known issue. There were long discussions about with the (I think) M9. IIRC the conclusion was that the mount was designed in 1950 or so at a time when such stress testing at long exposures was not thought about. Either its inherent design or specification tolerances were not good enough for this sort of exposure.

The solution was simple: put a broad rubber band or a hair tie (my kids called them 'scrunchies') around the mount. Light leak eliminated!

Edited by LocalHero1953
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This is common with the M mount from when the coding window was introduced with the M9. 

I guess nobody notices this unless you use long exposures on a tripod, hence the often recited 'it's never happened to me' response when the same sort of flare is questioned, but the leak comes from the critical sealing gap between the coding window and daylight. But go back to the days of the M9 and you can see discussions about the very same thing, and every now and again the same questions have cropped up ever since. The flare can be erratic because of the direction or intensity of the ambient light, but if the exposure is long enough it will happen. The old solution and one that still works is to use a hair scrunchy around the base of the lens. And I see @LocalHero1953 has just beaten me to the answer, grrr! 

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11 hours ago, hmzimelka said:

Hi again.

Today I wanted to try my hand at taking long exposures with an ND 3.0 10 stop filter. 

I used my new Summicron-m 50mm V, and got some light leaks. I tried covering different parts of the lens and camera and noticed an almost complete reduction of it when covering the mount of the lens/camera. 

I then came home and tested some lens and camera combinations with the lens cap on at f/16.

The Summicron-M 50mm was the worst. The Voigtlander Ultron 28mm ASPH and Color-Skopar 21mm f/3.5 were much much better but not free from light leaks either. 

 

Anyone brave enough to try this on their M11 and better yet other cameras too? 😮

 

 

 

First image: Summicron 50mm lens. 15sec exposure at ISO 64 with the lens cap on. No exposure compensation in Lightroom.

Second image: Ultron 28mm ASPH. Same exposure. No exposure compensation in Lightroom.

Third image: Ultron 28mm ASPH. Same exposure. A +4 exposure compensation in Lightroom.

 

 

Every lens I own does this at least to some extent. As noted, the primary source is near the 6-bit code reader. It is only ever an issue with astrophotography (if there is much local light pollution) or when shooting through a dark ND filter. For those situations, a scrunchie (pony tail clip) has always reduced the issue to a negligible level. As mentioned, it’s pretty universal for Leica M’s since the 6-bit coding was added.

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  • 1 year later...

I have tried some long exposures of 2 to 10 min with the M11 staking polar and nd filters up to 16 stops with 2 different lenses so far and found out that the light leaks are mostly related to the lenses.

The lens I have most leak problems with is the tri-elmar 16-18-21. This lens is leaking already at 2 minutes exposure and light seems to leak through only one area

With the Voigtländer 50mm f2 APO I had no issue. The lens is well sealed and leaves only light through the glass itself.

Needless to mention the frustration from the price difference...

Next time I will try covering the tri-elmar with a cloth as I do with my SLRs.

Hope this helps

 

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1 hour ago, Lopezso said:

I have tried some long exposures of 2 to 10 min with the M11 staking polar and nd filters up to 16 stops with 2 different lenses so far and found out that the light leaks are mostly related to the lenses.

The lens I have most leak problems with is the tri-elmar 16-18-21. This lens is leaking already at 2 minutes exposure and light seems to leak through only one area

With the Voigtländer 50mm f2 APO I had no issue. The lens is well sealed and leaves only light through the glass itself.

Needless to mention the frustration from the price difference...

Next time I will try covering the tri-elmar with a cloth as I do with my SLRs.

Hope this helps

 

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Can you confirm if the leak is consistently at the same place on the mount? The 6-bit code reader?

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It is a common technique with any camera to cover the camera (including the lens mount) with a dark cloth when shooting in strong daylight and strong ND filters.

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  • 1 month later...
On 4/16/2024 at 12:22 AM, LocalHero1953 said:

Can you confirm if the leak Issue consistently at the same place on the mount? The 6-bit code reader?

yes, that seems to be the case. Same place on the mount with the same lens where the 6-bit-code reader is located.

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