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Monochrom Long Exposure Issue


fotografr

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I'm hoping someone my technically savvy than myself can help solve a mystery for me. I was recently in Oregon photographing the northern coast area and did a large number of long exposures of 30 seconds to one minute. This was done using a B+W ND filter that reduced the exposure by 10 stops.

 

Many of the images done in this manner exhibited an overexposed area. I'm including samples below. In trying to recreate this at home, I've had the same thing show up, along with a different area, also shown in one image below.

 

I can't tell if this is a camera issue (light leak?) or something to do with the filter, or something else. It happened with different lenses both with and without lens shades. Anybody out there got a clue what's going on?

 

Thanks,

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Interesting (or, perhaps not...). Which lens did you use? See here and here for some discussion about reported/speculated light leakages.

 

Thanks very much. This happened primarily with my 24mm, but the image I shot at home trying to recreate the problem was done with the 35/2 asph. That one showed up in a different place.

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I'm so glad you posted this. I have had the same problem with the identical artefact pattern recently using a 10 stop B+W ND filter during daylight. I was going to post about this problem earlier but forgot.

 

This occurred on my M9 and Monochrom, and with a number of lenses including 1.4/21 SEM ASPH, 2.0/28 Summicron ASPH, 1.4/35 Summiux ASPH, 1.4/50 Summilux ASPH, 2.8/25 ZM Biogon, and1.5/50 ZM C-Sonnar.

 

It made no difference as to whether light sources entered from one or the other side of the lens.The filter was screwed on under the lens hoods (if they were fitted) so it was not a problem of light leakage and in many situations there were no strong light sources entering the lens. It was dependent only on the duration of exposure, ie the longer the exposure the more prominent the artefact. I. could not reproduce this with weaker filters

 

I assume that this is a result of internal reflections between the back of the filter and the sensor, and that one just can't use 10x ND filters for longer exposures on this digital sensor. Why this specific pattern I don't know.

 

Very frustrating - back to film for these shots.

 

I've just received my M240 so I'll test it out as soon as I can.

Edited by MarkP
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This is an issue with both the M9 and the MM. It is a light leak on the flange... I believe right where a small screw sits on the lens flange in the upper-left (over-exposing the lower right corner of the frame). I have been able to mitigate this on my M9 and MM by sealing the flange with a thick, black rubber band or one of my wife's rubber hair bands.

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That's outrageous if correct.

It would certainly explain why the artefact is so reproducible across the two cameras and all of these lenses & shooting conditions

 

Have you noticed this problem in any other situations?

 

I'll test it out myself this afternoon if I can.

It would be great to know that I can go back to using the 10XND filter.

 

 

Thanks so much kd

Edited by MarkP
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Hello Brent,

 

Nice photos.

 

A while back Karl-Heinz who writes as "k-hawinkler" wrote about the issue of filters & reflections from the sensor surface pertaining to the 280mm F4 Apo. If I knew enough about computers I would pop it up on the screen here. It might be instructive.

 

Best Regards,

 

Michael

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That's outrageous if correct.

It would certainly explain why the artefact is so reproducible across the two cameras and all of these lenses & shooting conditions

 

Have you noticed this problem in any other situations?

 

I'll test it out myself this afternoon if I can.

It would be great to know that I can go back to using the 10XND filter.

 

 

Thanks so much kd

 

Long exposures in bright sunlight. It doesn't happen on my long exposures at night because light isn't beating down on the camera. Others on the forum have had this happen and also recommended similar solutions. (That is how I learned about it).

 

I had a similar issue with my Nex 6 using a 21mm Super Elmar and a Voigtlander adapter. It was worse with the Nex, but of course adding the adapter adds multiplies the light leak risk.

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Hello Brent,

 

Nice photos.

 

A while back Karl-Heinz who writes as "k-hawinkler" wrote about the issue of filters & reflections from the sensor surface pertaining to the 280mm F4 Apo. If I knew enough about computers I would pop it up on the screen here. It might be instructive.

 

Best Regards,

 

Michael

 

Michael,

 

This particular issue is not filter reflection. I struggled with this for weeks... Removing filters, changing filters, cleaning sensors, building lens hoods, ... . Finally I asked about it on this forum and another forum member (sorry, I can't remember his name) explained the problem and offered a solution.

 

KDR

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This is an issue with both the M9 and the MM. It is a light leak on the flange... I believe right where a small screw sits on the lens flange in the upper-left (over-exposing the lower right corner of the frame). I have been able to mitigate this on my M9 and MM by sealing the flange with a thick, black rubber band or one of my wife's rubber hair bands.

 

That's very interesting and I appreciate the suggestion. My first thought when I discovered the problem was to try putting one of my wife's hair bands around the lens and push it tight against the mount. If that solves the problem, it certainly would be an easy solution.

 

Thanks to everyone for responding to this and helping clear up the mystery. I'd much rather be able to apply a fix myself than send the camera in for what could be a long repair period.

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Hello KDR,

 

Thank you for your response.

 

I wasn't necessarily thinking that this problem might only be causd by a problem with a filter. Altho I think that was what seemed to be the problem there.

 

As I remember: This Thread from around 2 years ago dealt with a number of possibilities as to why the problem occured. Karl-Heinz & the others who analyzed it with him are smart people, just like you & the other people in this Thread. There was a discussion of a number of possibilities just as is going on here.

 

I thought reviewing this prior Thread might be helpful because: Sometimes it is easier to fix a bicycle:

 

If you don't have to invent it first.

 

Because somebody already did.

 

Best Regards,

 

Michael

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Are these artefacts always showing on the right side of the image (meaning on the side of the sensor, closest to the battery, which sits on the left from the sensor in a Leica M9/MM) ?

 

You could try an experiment at home with two sets of batteries - one warmed up to body temp., the other cooled down in a fridge.

Have sufficient time between the test exposures, to have the entire battery-less camera at the same starting temp. before inserting the battery and commencing the exposure.

 

If you don't see artefacts on the unaltered exposure, you can likely expose them by pushing the DNG file in Lightroom further (with noise reduction dialled down) for your analysis.

 

This is just a poke in the dark of course.

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I have had exactly the same artefact appear on an image made with a 32 second exposure with my MM, but not my M9. It seems to only happen in bright light, or at least a bright sky as 40 second IR exposures under a dark canopy of trees are fine.

 

I don't buy the filter reflection argument, it doesn't look like a filter reflection, and I don't buy the bayonet flange light leak argument, it doesn't look typical of the case.

 

My first instinct was to see if an internal light leak might be doing it, say coming in via the viewfinder and through the rangefinder mechanism, because upside down and reversed that is where the artefact appears, next to the rangefinder arm. But comparing my MM with my M9 I see that certainly one of the operating arms and a screw head are both shinier on the MM that the duller finish on my M9, so I'm leaning towards an internal reflection off the rangefinder mechanism when there is a bright light entering the camera over a long period of time. If anybody who has both an MM and an M9 could also compare the factory finish of the rangefinder mechanism it might be helpful?

 

Steve

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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.:)

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Not to advert from your problem, but those are incredible landscape images. Some of the best yet that I've seen with the MM.

 

sorry this is off topic, but I wanted to express Jeffry that I really enjoyed his LFI gallery - great selection!

How do you usually post-process your files?

Edited by Xavier Forcioli
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It must come from only long exposures. I used the same filter on my Noctilux and MM for the past few days and haven't seen it. My exposures were all less than about 1 second.

 

These were all exposures of over 30 seconds. As mentioned above it does not occur at night but only daylight long exposures

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