M10-D metadata about lens aperture is suddenly incorrect or even static in DNG files

[fenykepesz]

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i experience a sudden new problem with my M10-D for the last 24h or so : the lens aperture (for years the same 50/14 Summilux) is not recorded properly in the DNG raw file.  not sure if the problem could be with the lens or the camera body.  i detached the lens twice, played with its dials, no prevail.  lately the number stays 4.0, a static value, despite going from 1.4 up to 16 for  the purpose of testing.

i will need to locate my other lenses to see how they perform in this respect - so that's the next step of testing.

but what can i do meanwhile ?  i am not terribly disturbed as light metering works independently and i work anyway exclusively manually - but it would be nice and useful at times to see the aperture settings show up correctly recorded in my photo manager database...

[fenykepesz]

in FOTOS the actual f-number is empty - just a dash '-' is displayed.  everything else works via FOTOS (which i never use), and also all other metadata entries look fine.

now i really need to find my other lenses...

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[fenykepesz]

while playing with the aperture ring on my 35/1.4 Summilux the f-values are not correctly read either by the camera.  the values are allover the place, inconsistent, though they do appear to be less 'static' on with the 50/1.4 with its 'static' "4.0".

is this something mechanical or optical ?  how is the aperture setting conveyed to the M camera body ?

what else can i do ?  any suggestions ?

[RobW0]

12 minutes ago, fenykepesz said:

while playing with the aperture ring on my 35/1.4 Summilux the f-values are not correctly read either by the camera.  the values are allover the place, inconsistent, though they do appear to be less 'static' on with the 50/1.4 with its 'static' "4.0".

is this something mechanical or optical ?  how is the aperture setting conveyed to the M camera body ?

what else can i do ?  any suggestions ?

There is no mechanical connection between the camera and lens in the M mount. It is just a best guess that is put in the meta data. My best guess, is that it is done by using the brightness sensor and the meter reading in some way. The only thing the camera knows is what the max aperture of an encoded lens is.

Edited November 8, 2023 by RobW0

[fenykepesz]

vor 2 Minuten schrieb RobW0:

There is no mechanical connection between the camera and lens in the M mount. It is just a best guess that is put in the meta data. My best guess, is that it is done by using the brightness sensor and the meter reading.

thank you, RobW0 - i also saw such a note when googling the problem earlier but i thought it was joke !  wow, so the interplay between brightness sensor and the meter reading on the curtain has to be perfect so the camera can approximately determine the lens aperture - wow !  hard to believe - but i believe you

what's next now ?  as far as i know there is no issue with the brightness sensor nor is its window more dirty than usual (i just wiped it)....

[RobW0]

1 minute ago, fenykepesz said:

thank you, RobW0 - i also saw such a note when googling the problem earlier but i thought it was joke !  wow, so the interplay between brightness sensor and the meter reading on the curtain has to be perfect so the camera can approximately determine the lens aperture - wow !  hard to believe - but i believe you

what's next now ?  as far as i know there is no issue with the brightness sensor nor is its window more dirty than usual (i just wiped it)....

I am not sure if that is how it comes up with what to put in the meta data, but I do know that it is some kind of educated guess by the camera.

[fenykepesz]

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i see, thank you for the feedback.

in any case, the brightness sensor seems to work properly, as it scales the red LEDs and the white frame lines (slightly lagging) accordingly, as expected.

[evikne]

5 hours ago, fenykepesz said:

but what can i do meanwhile ?  i am not terribly disturbed as light metering works independently and i work anyway exclusively manually - but it would be nice and useful at times to see the aperture settings show up correctly recorded in my photo manager database...

I use an LR plugin called LensTagger. It won't remove the cause of your problem, but it can help you correct the metadata afterwards so it appears correctly in your image organizer.

[newtoleica]

The aperture reading is always approximate for the reasons discussed…. Actually pretty useless…. It doesn’t matter. 

[fenykepesz]

vor 5 Stunden schrieb evikne:

I use an LR plugin called LensTagger. It won't remove the cause of your problem, but it can help you correct the metadata afterwards so it appears correctly in your image organizer.

 

vor 5 Stunden schrieb newtoleica:

The aperture reading is always approximate for the reasons discussed…. Actually pretty useless…. It doesn’t matter. 

i am truly somewhat baffled by the current lens aperture 'reading' solution in M cameras - i had no clue.  it also looked pretty functional and 'correct' for the last few years, till 1-2 days ago.  anyway, perhaps it doesn't matter, the photos look ok. 

now, just purely from a technical point of view, what happened 2 days ago ?  how come this problem doesn't affect other functionalities in my M10-D ?  as said, the brightness sensor appears to be pretty responsive...

[RobW0]

1 hour ago, fenykepesz said:

 

i am truly somewhat baffled by the current lens aperture 'reading' solution in M cameras - i had no clue.  it also looked pretty functional and 'correct' for the last few years, till 1-2 days ago.  anyway, perhaps it doesn't matter, the photos look ok. 

now, just purely from a technical point of view, what happened 2 days ago ?  how come this problem doesn't affect other functionalities in my M10-D ?  as said, the brightness sensor appears to be pretty responsive...

The meter does not care what the lens aperture is set at. It measures the light that it sees and then sets the exposure. It is not like an SLR camera that has the aperture open and only closes it when the picture is taken. The aperture opens and closes as you turn the ring.  If the lens is 6-bit coded then the electronics in the camera know what the min and max apertures are for that lens, that is all. From that it can make a guess as to what aperture was used. That guess is not used for anything other than putting it in the meta data for reference. 

[RexGig0]

One thought: Check to see that code on your Summilux 50mm is clearly readable, so that the camera fully recognizes the lens.

[fenykepesz]

vor einer Stunde schrieb RexGig0:

One thought: Check to see that code on your Summilux 50mm is clearly readable, so that the camera fully recognizes the lens.

that's what i did first, checked those (optical) contacts, thank you, RexGig0 - and they look fine, on the camera and on both 35/1.4 and 50/1.4 Summiluces.

now, in both FOTOS and produced DNG files the inserted lens name and specs are picked up properly, so that seems to be fine.  but as said earlier, in FOTOS in Remote mode the f-tops aperture field is blanked out with two dashes '--'.  i never used FOTOS before so i am not sure what the default behaviour is in this respect - still, it looks fishy anyway, as the camera does not seem to do any 'guess' work regarding the lens aperture reading. 

as i just took some test pics some seconds ago, i see that the lens is picked up correctly, while the F-value can range from noctiluxi 1.0 to 1.5 for example ?  these are not values that correspond with a 50/1.4, right ?  i may need to take out the battery for a minute which may reset the camera 'memory'.

the only reason i continue this thread here is that i am curious and try to explain what did supposedly happen technically 2d ago, for no reason apparently...?

Edited November 8, 2023 by fenykepesz

[mujk]

As already noted by @RobW0, the indicted F value is a guesstimate based on the readings by the exposure meter and the brightness sensor. I don't know if the camera actually uses any information about the lens in this process. Using an ND or other filter that reduces the amount of light going through the lens will cause a systematic error in the reading. Blocking the brightness sensor will of course also disturb it.

If I understand it correctly, everything else is working fine and images are correctly exposed. In that case I would suspect the problem to be somewhere in or around the brightness sensor or in the way the output from this is read/interpreted by hardware or software for the purpose of producing the F value guesstimate (using sensor output for frameline and OVF led display brightness may be a different process). A software problem might me cleared by a full power off (taking out the battery) as you suggest or by a reset to factory settings.

[fenykepesz]

thank you for your feedback @mujk !  yes, i fully agree with all your points : the path for the F-value guesstimate process must go on a different track as the computed F-values can vary totally meschugeneh while at the same time the LED/frames are processed as expected, suggesting that the little brightness sensor works normally.  strange !

and thanks to your replay i also finally found out how to create those oval @ referrals like you had one for @RobW0 for example !