EXIF data oddity with lens detection off

[helohe]

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Today I took some pictures with the M10-P and a Voigtlander ultra wide 12mm, to do this I turned lens detection off. This was also confirmed when I looked at the information display.

However now upon reviewing this photos, I noticed that the EXIF data (can be checked for example here: http://exif.regex.info/exif.cgi) shows the lens as Apo-Summicron-M 1:2/90 ASPH. This is the lens I used before that. It does not have any effect on the quality as far as I can see but when I want to organize my photos by lens type it goes to the wrong category now instead of uncategorized.

Anyone else notice such behavior with lens detection turned off?

[farnz]

It started back in 2006 with the first 6-bit flange that was on the M8.  It's normally owing to where a screw in the lens flange happens to be and the 6-bit system detects the lens as a 90 Summicron.

Pete.

[jdlaing]

Wait a minute Pete.

If lens detection is off it shouldn’t read the screw.

[adan]

The M10 series (unlike earlier M digitals) will revert to the last manually-selected lens, if it does not detect a coded lens mounted. Which is good - it allows one to have a single uncoded lens and have it show up in EXIF along with all the other lenses like a coded lens, without having to mess with the menu at all. I.E., it automatically swaps between manual and auto lens selection depending on whether it detects a code or not.

The "screw-head as coding dot" does not code for the 90 Summicron, but for the 90 Tele-Elmarit-M v.2 (thin). The oh-so-convenient ooo•oo pattern. (If you have a dirty lens mount, it might read it as the Summicron - ooo•••). But you were close - and generally correct as to the mechanism.

In any case, Voigtlander's flange screws are not positioned the same as Leica's - CV uses 4 screws at 90° apart - Leica uses 6 at 60° apart (approximately) - or 5 on coded lenses, to leave the gap for the coding.

As to the OP"s question:

1) which 12mm Voigtlander lens are you using? There have been three since 1999: v. I screw-mount that needs an M adapter, v. II native M mount with v. I glass, and recent v. III with optics totally re-designed to be more digital-friendly. Gotta know exactly what you're working with.

2) if the first, the M adapter may be what's fouling up the lens detection.

3) the M10 "feature" of always being able to detect and label one uncoded lens has changed the logic of the M10's lens detection firmware - it can become confused by poor coding or no coding (I had a hand-coded 90mm pre-ASPH Summicron lens that was occasionally ID'd as a 35 f/1.4 ASPH - which makes no sense at all - not even the correct frameline group.) The R-lens adapter or 90mm Macro extension ring also occasionally show up as the detected lens, for no obvious reason.

4) additionally, there have been other examples of a "disconnect" between what the camera INFO says, and what appears in EXIF on a computer later. E.G. at one point the exposure comp used would be "forgotten" if the image was replayed later on the camera, and show as "zero." And a 135 f/4 lens would show as "135 f/4.0" in the info immediately after the picture was taken - and then as "135mm f/3.99" if viewed on the camera later - and then revert to "135.0mm Tele-Elmar 1:4/135" in Bridge or Lightroom on a computer.

[helohe]

16 hours ago, adan said:

The M10 series (unlike earlier M digitals) will revert to the last manually-selected lens, if it does not detect a coded lens mounted. Which is good - it allows one to have a single uncoded lens and have it show up in EXIF along with all the other lenses like a coded lens, without having to mess with the menu at all. I.E., it automatically swaps between manual and auto lens selection depending on whether it detects a code or not.

The "screw-head as coding dot" does not code for the 90 Summicron, but for the 90 Tele-Elmarit-M v.2 (thin). The oh-so-convenient ooo•oo pattern. (If you have a dirty lens mount, it might read it as the Summicron - ooo•••). But you were close - and generally correct as to the mechanism.

In any case, Voigtlander's flange screws are not positioned the same as Leica's - CV uses 4 screws at 90° apart - Leica uses 6 at 60° apart (approximately) - or 5 on coded lenses, to leave the gap for the coding.

As to the OP"s question:

1) which 12mm Voigtlander lens are you using? There have been three since 1999: v. I screw-mount that needs an M adapter, v. II native M mount with v. I glass, and recent v. III with optics totally re-designed to be more digital-friendly. Gotta know exactly what you're working with.

2) if the first, the M adapter may be what's fouling up the lens detection.

3) the M10 "feature" of always being able to detect and label one uncoded lens has changed the logic of the M10's lens detection firmware - it can become confused by poor coding or no coding (I had a hand-coded 90mm pre-ASPH Summicron lens that was occasionally ID'd as a 35 f/1.4 ASPH - which makes no sense at all - not even the correct frameline group.) The R-lens adapter or 90mm Macro extension ring also occasionally show up as the detected lens, for no obvious reason.

4) additionally, there have been other examples of a "disconnect" between what the camera INFO says, and what appears in EXIF on a computer later. E.G. at one point the exposure comp used would be "forgotten" if the image was replayed later on the camera, and show as "zero." And a 135 f/4 lens would show as "135 f/4.0" in the info immediately after the picture was taken - and then as "135mm f/3.99" if viewed on the camera later - and then revert to "135.0mm Tele-Elmar 1:4/135" in Bridge or Lightroom on a computer.

Its the version 2 of the lens. The problem looks very much like what you describe in point 4. The INFO says no lens / lens detection off. But then the exif shows Summicron-M 1:2/90 ASPH. Funnily enough the exif somewhere else also shows the focal length as 0.0mm (at least that is what is shown for the pictures I put on flickr).

[adan]

4 hours ago, helohe said:

Funnily enough the exif somewhere else also shows the focal length as 0.0mm

That is "normally" normal for an undetected lens. Means "unknown focal length."

Anyway, as to making your 12mm pictures searchable or categorized...let me go sideways for a moment

• Except for the missing or incorrect EXIF, are you happy with how your 12mm pictures look? Do you notice any obnoxious color stains or excess vignetting once in Lightroom? One of the important functions of ID'ing lenses (especially superwides) on a digital M is that they can produce edge color stains - the 15mm CV v.1/2 is horrible in that regard. But, 1) the 12mm always behaved a little better, and 2) the M10 sensor has been improved somewhat (not completely). ID'ing them allows the camera to remove the "known" patterns of stains for every given Leica lens back to 1980 or so. But if your pictures look OK to you "as is," you don't need that aspect of the coding to work.

• What other lenses do you use - Are they all 6-bit coded?

• Is there some older Leica lens and focal length that you know you will never use? But appears in the M10's M-lenses menu? E.G. 135mm Elmarit. (You want a "dummy" focal length longer than 50mm to do this.)

Because, as I mentioned in my previous post, point (1), the M10 allows you one "freebie" uncoded lens. If you are fine with how your 12mm pictures look when tagged as "90mm" or "0.0mm," and with having your 12mm pix tagged as "135 Elmarit," and all your other lenses are coded, then you can set up your camera to always be in Auto Lens detection (instead of Lens Detection OFF), but with the default setting for uncoded lenses being "135 Elmarit."

Then: the M10-P recognizes your coded lenses correctly. When it sees your 12mm mounted, it says to itself, "A-ha - uncoded lens - use the current menu selection = 135 f/2.8." Applies virtually zero corrections (since the 135 is a tele, not wide). And tags your 12mm pictures that way. And then you can sort or categorize for "focal length = 135 Elmarit" - and see only your 12mm pictures.

That is just a way of forcing the camera to apply a fixed lens ID to your 12mm, rather than randomly using "90 APO" or "0.0mm." Without messing up your pictures with weird unneeded corrections.

 

[mujk]

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On 8/8/2019 at 6:33 AM, adan said:

Because, as I mentioned in my previous post, point (1), the M10 allows you one "freebie" uncoded lens. 

You can actually have a separate "freebie" for each profile. So if you don't use profiles for other purposes you can select the uncoded lens by changing profile. Works pretty well unless something else messes up automatic detection.