[Leica] IMGS: Tests with MM and M246 - Howard and Peter

[Jay Burleson]

I am stretching my DNG knowledge here, but what I THINK is going on is 
that the MM handles some aspects of writing exif info in a non-standard way.
Perhaps Capture One is looking for the aperture info where it is 
supposed to be, per Adobe DNG exif standards, and it isn't there.
LR may have a workaround developed with Leica.
I know that MM DNG files are not standard because they (still!) cannot 
be used by the LR CC merge to panorama tool because of incorrect exif 
parameters that the merge tool uses to work with blending layers.

Jay

On 2/11/2016 8:18 PM, Peter Klein wrote:
> Jay:  I mentioned this in the other thread that in which Howard's question
> appeared, but I'll ask you here as well:
>
> Do you know why Capture One displays my M8's estimated f-numbers, but not
> my (MM) Monchrom's?
>
> --Peter
>
> On Thu, Feb 11, 2016 at 7:51 PM, Jay Burleson <leica at jayburleson.com> wrote:
>
>> Top center left on the front of an M body is a small window which contains
>> a metering cell that meters the environmental light, in order for the
>> camera to be able to guesstimate the lens aperture. This is relevant for
>> in-camera vignetting correction as well as EXIF data.
>> It compares the light coming to it with the value of the max aperture as
>> reported by the 6-bit coding and comes up with a (sometimes spurious)
>> number. For example, use of the exposure compensation will really throw it
>> off. I run -2/3 almost all the time on my MM and it reports to me that my
>> Summilux wide open is f/1...
>>
>> Jay
>>
>> On 2/11/2016 5:35 PM, Howard Ritter wrote:
>>
>>> Can anyone explain how Lightroom reports an aperture for images made with
>>> M cameras, which don’t have a way to report their aperture setting to the
>>> camera? All the camera knows is what the lens’s maximum aperture is, as
>>> reported by the 6-bit code or manually.
>>>
>>> I just ran off a series of images with a coded 24/2.8, one at each usual
>>> stop from 2.8 to 16. LR reports the apertures as 2.8, 3.4, 4.8, 6.8, 9.5,
>>> and 13. The aperture could be inferred from the integrated light intensity,
>>> but only if the camera knows the intensity of the illumination of the
>>> subject, which of course it doesn’t. I’m puzzled not only by the fact that
>>> LR reports an aperture setting, which the camera has no means of knowing,
>>> but even more by the fact that the values are different for each exposure,
>>> increasing continuously in the right direction, and most of all by the fact
>>> that the values are, as Tina says, in the ball park. And the Mac’s Preview
>>> app reports an Aperture Value, which for the same sequence of images also
>>> increases correctly, but ranges from 2.97 to 7.4.
>>>
>>> With a non-coded 35/1.4 and lens data entered manually, LR reports the
>>> apertures as 1.4, 2, 2.8, 4, 4.8, 8, 9.5, and then drops to 4 for f/22.
>>> Preview does much the same thing but less accurately, reporting a
>>> progression from 0.97 to 6.5, but then dropping to 6 for f/22.
>>>
>>> With the same non-coded lens, but the lens data manually entered
>>> incorrectly as 90/2, LR gave the apertures as 2, 2, 2.8, 4.8, 5.6, 8, 9.5,
>>> and 4. Preview gave them as 2, 2, 2.97, 4.5, 4.96, 6, 6.49, 4.
>>>
>>> I am completely baffled. Anyone have an answer? How do the programs
>>> derive a value for f/stop? Since LR and Preview report different apertures
>>> for the same exposure, it can’t be just information supplied by the camera.
>>> The camera knows what the maximum aperture of each lens is, but what, the
>>> camera or the program, or both, decides that a lens is set to that, or to
>>> anything smaller?
>>>
>>> —howard