M7 Metering Overexpose Compared to M11

[Levpush]

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Hello everyone, I recently acquired a used M7 and I found the exposure metering seems always one stop overexpose compared to my M11 using center-weighted metering. Is it normal and something Film Leica deliberately do? 

I did shot one roll with the M7 and it doesn't seem too bad. The sky was indeed overexposed a bit and I have to bring it down in LR for almost all of them. But I know film is in general ok with a bit of overexposure.

Thanks

Edited July 25, 2022 by Levpush
typo

[pedaes]

3 minutes ago, Levpush said:

I did shot one roll with the M11

M7?  I expect M11 to be more accurate - you do not want to overexpose a sensor and 'blow' highlights. The dynamic range of a sensor means shadows can be recovered, but if highlights are lost they are gone - zero information recorded.

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[Levpush]

1 minute ago, pedaes said:

M7?  I expect M11 to be more accurate - you do not want to overexpose a sensor and 'blow' highlights. The dynamic range of a sensor means shadows can be recovered, but if highlights are lost they are gone - zero information recorded.

Yes sorry, I meant M7. I feel the M7 overexposes by a stop compared to M11(which I use as the correct reference), should I consider sending it for a recalibration?

[earleygallery]

The two cameras meter rather differently. The M7 has what you could consider as a 'fat' spot meter - reading the manual will explain all.

[Levpush]

7 minutes ago, earleygallery said:

The two cameras meter rather differently. The M7 has what you could consider as a 'fat' spot meter - reading the manual will explain all.

I see, I don't have a grey card but I tried to point both cameras to my wooden floor which has an even brightness. M7 reading is still one stop overexpose compared to the M11, not sure if this method is fair or not to remove the metering method differences.

[adan]

Don't forget that film ISOs and digital ISOs are calculated somewhat differently, so if you are setting your M7 to "ISO 400" and your M11 to "ISO 400," there is no reason they will tell you exactly the same exposure.

Briefly, and thus incompletely - film ISO is (generally) measured and calculated based on the density of the shadows in a physical negative, as compared to unexposed-but-processed film (film-base density plus fog).

Digital ISO is measured and calculated by reading signal/brightness and noise outputs in .jpg files (not even raw/.dng values, since those will be adjusted by anyone, in post-processing). And there are 3-5 different-but-ISO-approved methods for doing that - manufacturers are free to use any of the 3-5 methods.

See: https://www.iso.org/obp/ui/#iso:std:iso:12232:ed-3:v1:en

And compare to : https://www.standards-pdf-download.com/iso-6-1993-download-free.html for B&W film speeds, or https://cdn.standards.iteh.ai/samples/11948/16e890e046374a689c753d3d8c88c0bc/ISO-5800-1987.pdf for color neg film speeds

All a user can really do (absent a laboratory setup for the whole imaging chain - densitometers, signal-processing gear) is compare final results - does the M7 meter give you a "well-exposed" film negative and print, and does the M11 give you a "well-exposed" digital .jpg, using each camera set to the same ISO?

Or use an independent method for setting exposure with both cameras (ISO, aperture, shutter) and compare those. A hand-held meter, or a "sunny 16" estimation exposure.

Edited July 26, 2022 by adan

[Knipsknecht]

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... not to forget the way the lab developed the film. 

[Levpush]

4 hours ago, adan said:

Don't forget that film ISOs and digital ISOs are calculated somewhat differently, so if you are setting your M7 to "ISO 400" and your M11 to "ISO 400," there is no reason they will tell you exactly the same exposure.

Briefly, and thus incompletely - film ISO is (generally) measured and calculated based on the density of the shadows in a physical negative, as compared to unexposed-but-processed film (film-base density plus fog).

Digital ISO is measured and calculated by reading signal/brightness and noise outputs in .jpg files (not even raw/.dng values, since those will be adjusted by anyone, in post-processing). And there are 3-5 different-but-ISO-approved methods for doing that - manufacturers are free to use any of the 3-5 methods.

See: https://www.iso.org/obp/ui/#iso:std:iso:12232:ed-3:v1:en

And compare to : https://www.standards-pdf-download.com/iso-6-1993-download-free.html for B&W film speeds, or https://cdn.standards.iteh.ai/samples/11948/16e890e046374a689c753d3d8c88c0bc/ISO-5800-1987.pdf for color neg film speeds

All a user can really do (absent a laboratory setup for the whole imaging chain - densitometers, signal-processing gear) is compare final results - does the M7 meter give you a "well-exposed" film negative and print, and does the M11 give you a "well-exposed" digital .jpg, using each camera set to the same ISO?

Or use an independent method for setting exposure with both cameras (ISO, aperture, shutter) and compare those. A hand-held meter, or a "sunny 16" estimation exposure.

Thanks that explains a lot of my confusion. Yes the only roll I shot with M7 seems fine in general. Cheers

[a.noctilux]

6 hours ago, Levpush said:

Thanks that explains a lot of my confusion. Yes the only roll I shot with M7 seems fine in general. Cheers

B&w or color negative film ?

[Levpush]

1 minute ago, a.noctilux said:

B&w or color negative film ?

Color negative, but the discrepancy I mentioned at OP is probably irrelevant to which type of film it’s loaded

[a.noctilux]

Yes, I know.

Tolerance of color negative can be so great that the results can be acceptable even if the meter is out of whack.

If I follow well your M7 is gone for repair ?

I have some interest in buying one M7 soon 😄.

Edited July 26, 2022 by a.noctilux

[Levpush]

1 minute ago, a.noctilux said:

Yes, I know.

Tolerance of color negative can be so great that the results can be acceptable even if the meter is out of whack.

If I follow well your M7 is gone for repair ?

No it hasn’t. I was just messing with it and M11 the other day and realized the difference in the meter reading, thought the M7 might be acting weird.

funny story with my experience with the M7, I bought a used one from B&H the first time and found a dark vertical line on every frame when using shutter speed > 500, returned it, and bought another one which is this one. So I was indeed a bit more nervous about M7 than my other cameras given experiencing issue first time 

[Helge]

It’s clear that the difference is independent of the film used. From my point of view you could only verify the difference by using a grey card or any other surface that shows a completely even and undirected reflection behavior combined with an as equal as possible illumination.

Otherwise you won‘t be able to eliminate different weighting between the two meters. And still, at the end a difference of 1/2 a stop seems still correct.

The idea that ISO values are differently calculated seems to me a myth, since it would prohibit using a separate meter which don’t distinguish between analogue and digital.

Edited July 26, 2022 by Helge

[a.noctilux]

Thanks @Levpush.

Or I'll delay for some more time, having read so many complains from M7 users, and so many happy M7 users.

[Levpush]

7 minutes ago, Helge said:

It’s clear that the difference is independent of the film used. From my point of view you could only verify the difference by using a grey card or any other surface that shows a completely even and undirected reflection behavior combined with an as equal as possible illumination.

Otherwise you won‘t be able to eliminate different weighting between the two meters. And still, at the end a difference of 1/2 a stop seems still correct.

The idea that ISO values are differently calculated seems to me a myth, since it would prohibit using a separate meter which don’t distinguish between analogue and digital.

I agree. For me the only realistic way is to look at the shots from the M7, and so far I probably shouldn’t be worried

[Levpush]

7 minutes ago, a.noctilux said:

Thanks @Levpush.

Or I'll delay for some more time, having read so many complains from M7 users, and so many happy M7 users.

I would say if you can find one from a reputable source with some sort of warranty or return policy and later version(with MP finder) it is a such a pleasurable camera to use. I enjoy shooting with it more than M11 tbh

[ktmrider2]

There will be differences between any two meters reading the same scene, even if they are identical models.  I believe there is a tolerance of up to a stop.  Why sweat it if your M7 is producing exposures which result in good negatives and prints?

[andrew01]

I found this article interesting in relation to metering strategies for film:

http://www.johnnypatience.com/the-zone-system-is-dead/

 

The key message for negative film is that it is better to bias towards overexposure, and therefore avoid thin negatives.

Do this by pointing the meter towards darker tones in the scene.  As long as there is enough detail in the negative you can achieve whatever look you want (high or low key) during scanning/printing.  

 

I wouldn’t stress about meter differences between film and digital cameras.  Judge the results by shooting a few rolls and looking at the density of your negatives.

Edited July 26, 2022 by andrew01

[Levpush]

3 hours ago, andrew01 said:

I found this article interesting in relation to metering strategies for film:

http://www.johnnypatience.com/the-zone-system-is-dead/

 

The key message for negative film is that it is better to bias towards overexposure, and therefore avoid thin negatives.

Do this by pointing the meter towards darker tones in the scene.  As long as there is enough detail in the negative you can achieve whatever look you want (high or low key) during scanning/printing.  

 

I wouldn’t stress about meter differences between film and digital cameras.  Judge the results by shooting a few rolls and looking at the density of your negatives.

Thanks for the article, it was a nice read. And I agree with your pov

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[250swb]

10 hours ago, andrew01 said:

I found this article interesting in relation to metering strategies for film:

http://www.johnnypatience.com/the-zone-system-is-dead/

 

The key message for negative film is that it is better to bias towards overexposure, and therefore avoid thin negatives.

Do this by pointing the meter towards darker tones in the scene.  As long as there is enough detail in the negative you can achieve whatever look you want (high or low key) during scanning/printing.  

 

I wouldn’t stress about meter differences between film and digital cameras.  Judge the results by shooting a few rolls and looking at the density of your negatives.

It's an 'interesting' article, he's constructed his argument like a person with two screws left over from building a flatpack cupboard, it still a cupboard but somewhere along the way he's not paid attention. To demolish the Zone System as comprehensively as he thinks he has he needs to understand it, and he doesn't, he's working on hearsay, making fundamental errors, and then making his theory fit as a talking point. All he has done is make another theory, like many photographers do who each have their own way of working, but it's no way the heroic effort that slays dragons and rescues the Princess from Zone V.