Monochrom Long Exposure Issue

[MarkP]

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I think a bit of experimentation covering and uncovering the VF windows should be enough to determine whether the light is leaking through the flange (I agree it seems unlikely) or coming from the RF area (IMO more likely). This has been an interesting and timely thread because I have recently dug out a 13 stop ND filter and was planning on using it tomorrow for some landscape stuff. I'll try and remember to wrap the camera body when doing long exposures.

 

Please report back to us

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[MarkP]

Please report back to us

 

OK. So I did some experimenting with an exceptionally bright torch (LedLenser M7), M9/Monochrom/M240, 1.5/50C-Sonnar and 1.4/50 Summilux ASPH.

 

Exposed each mount quadrant directly to bright light, and passed light around the mount i circles. with & without protecting VF windows from light. Also exposed VF windows to light with the lens mount protected.

 

No light leak through VF windows

Light leak through left upper quadrant of mount under VF window. Little if any leak at any other quadrants. M9 with marked sensor blooming) worse than Monochrom, don't know why. M240 much better but still leaks a bit through this quadrant.

 

The conditions are indeed forced but would simulate a long exposure in bright daylight with a 10-stop ND filter

 

kd is indeed correct and now I know how to protect the sensor from the light leak in such conditions.

[Al Leb]

That is a very useful contribution, thank you very much.

[kdriceman]

Here is what I did this morning. Both are 32 s dark exposures (MM and 50 summilux) with the lens cap on and a bright light shining on the upper left corner of the camera (flange and vf included). The first is with the flange exposed and the second is with the flange protected with a tight hair band (see additional pictures).

 

I have wrestled with this issue with both my M9 and my MM and have found protecting the flange from light will usually get a usable image. I am convinced that the flange is the culprit. Yes, I know light does not curve around corners, but we all know it reflects endlessly off reflective surfaces... and both flange surfaces on MM, M9 and M lenses are very reflective.

 

I encourage you to experiment yourselves to be convinced.

 

Thanks,

 

KDR

 

PS: Both images processed in LR with only adjustment being a +3 stop exposure adjustment.

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[MarkP]

KD,

 

I also found my daughter's black fabric hair elastic worked quite well. . A small roll of Blu Tack is also easy to apply and works quite well.

 

If you expose just that corner of the mount to an extreme light source you can get severe flare/blooming across much of the sensor radiating from the bottom right hand corner of the image.

 

Thanks again for identifying the problem. It never would have occurred to me that the lens /mount interface could possibly leak light onto the sensor.

 

Regards,

Mark

Edited September 17, 2013 by MarkP

[kdriceman]

KD,

 

I also found my daughter's black fabric hair elastic worked quite well. . A bit of Blu Tack is also OK

 

If you expose just that corner of the mount to an extreme light source you can get severe flare/blooming across much of the sensor radiating from the bottom right hand corner of the image.

 

Thanks again for identifying the problem. It never would have occurred to me that the lens /mount interface could possibly leak light onto the sensor.

 

Regards,

Mark

 

It was someone else on the forum that alerted me a year or so ago. The forum has been a tremendous resource for me on many occasions.

[MarkP]

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It was someone else on the forum that alerted me a year or so ago. The forum has been a tremendous resource for me on many occasions.

 

 

Agreed.

[Bill W]

Leica! Hello. Perhaps this should not be happeneing. They need to issue hairbands or black rubber bands with every camera body

[wattsy]

Here is what I did this morning. Both are 32 s dark exposures (MM and 50 summilux) with the lens cap on and a bright light shining on the upper left corner of the camera (flange and vf included). The first is with the flange exposed and the second is with the flange protected with a tight hair band (see additional pictures).

 

Pretty conclusive. Thanks for sharing. Looks like I shall have to pinch one of my daughter's hair bands to put in my camera bag.

[fotografr]

I think a bit of experimentation covering and uncovering the VF windows should be enough to determine whether the light is leaking through the flange (I agree it seems unlikely) or coming from the RF area (IMO more likely). This has been an interesting and timely thread because I have recently dug out a 13 stop ND filter and was planning on using it tomorrow for some landscape stuff. I'll try and remember to wrap the camera body when doing long exposures.

 

I tried that while on my trip. I covered the viewfinder windows separately, then together, then I tried covering the eyepiece. I still had the problem. Interestingly, I was in a darkened hotel room doing these tests and was still getting the problem. I'm going to try further tests today with a covering (hair band) over the area where the lens mounts to the body. If my results are the same as KDR's, and I think they will be, then we will have a definitive answer.

Edited September 17, 2013 by fotografr

[wattsy]

If my results are the same as KDR's, then I think we will have a definitive answer.

 

I'm already persuaded by KDR's findings but it won't hurt to have corroborative evidence.

[MarkP]

Well mine were on three cameras with two different lenses.

[kdriceman]

Leica! Hello. Perhaps this should not be happeneing. They need to issue hairbands or black rubber bands with every camera body

 

An official Leica accessory rubber band flange seal... black with a Leica red dot - priced at $179.95!

 

I tend to agree that it should not be happening. I wonder if it happens on an MP or other film camera using film. I'm trying to remember the last time I tried a similar exposure with my film cameras, but I don't recall seeing this on film. But, you would think the flanges are the same, thus the leak would be the same.

 

At the same time, I have been able to work around it fairly well once it got figured out.

[fotografr]

 

At the same time, I have been able to work around it fairly well once it got figured out.

 

And that's really all that matters. My desire in starting this thread wasn't to give Leica another black eye--just to figure out what the problem was and what to do about it. This would seem to be a pretty easy and inexpensive solution.

 

I'm still absolutely delighted with my M Monochrom. The prints I've made from my last trip are exquisite.

[250swb]

Well done with the testing guys!

 

This isn't the same problem that the older leaky Zeiss lens flanges caused, where a screw hole on the mount and one on the lens flange coincided, but looks like light could eventually be getting into the camera from the cut out in the flange for the focusing cam. In fact the shape of the artefact does have a curve to it. All of which means the lens flange and bayonet mount can't be a very accurate fit together.

 

Steve

[brill64]

Both these types of flare could also be caused by filters in front of your lens? Is it an nd or ir? Remove them & reshoot. They can cause internal reflections. Probably from the shutter box or lens throat combined with a light source, however slight, just out of your frame, heightened by the long exposures. There's nothing wrong with your camera.

Edited September 17, 2013 by brill64

[algrove]

Well, I went into a store near me buy some black hair bands and the clerk, a guy who likes to play with hair I guess, was all over me about getting a black hair band for my silver hair and why not get silver, etc. I told him I liked the contrast and had made my decision on the color before leaving home. He went around and around while holding up different hair bands to my head so much that I left in disgust.

 

I still do not have a black hair band yet and must drive to Walmart where no one helps you so I can shop for a black hair band in total peace. What I will do for my camera and images!

[wattsy]

Both these types of flare could also be caused by filters in front of your lens? Is it an nd or ir? Remove them & reshoot. They can cause internal reflections. Probably from the shutter box or lens throat combined with a light source, however slight, just out of your frame, heightened by the long exposures. There's nothing wrong with your camera.

 

KDR's test was conducted with a lens cap in place.

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[kdriceman]

KDR's test was conducted with a lens cap in place.

 

Yep, lens cap on for both images. Additionally the light was directed right at the upper left part of the camera. I've had plenty of experience with unwanted reflections caused by filters and this is different. Additionally I have done this with and without filters (although not today) and the result is the same. In fact when I first noticed this artifact with my M9 my initial reaction was that its a filter reflection, so I took the filter off. It had no effect whatsoever.

[MarkP]

Well, I went into a store near me buy some black hair bands and the clerk, a guy who likes to play with hair I guess, was all over me about getting a black hair band for my silver hair and why not get silver, etc. I told him I liked the contrast and had made my decision on the color before leaving home. He went around and around while holding up different hair bands to my head so much that I left in disgust.

 

I still do not have a black hair band yet and must drive to Walmart where no one helps you so I can shop for a black hair band in total peace. What I will do for my camera and images!

 

Get a daughter!