My M8 recognizes my uncoded 35 mm Summicron v4!

[roelandinho]

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Hi fellow M8 users, 

Some time ago I got my Leica M8 and 35 mm Summicron v4 back from a maintenance trip to Wetzlar. I was using camera and lens together with a Leica UV/IR filter attached for accurate color. On the camera I set the Lens Detection setting to "On+UV/IR", even though my lens is not coded because I figured maybe for uncoded lenses it still tries to do some default (i.e. minimal, conservative) corrections. I was amazed to find out my camera actually "recognized" the v4 Summicron! Could it be that this lens is the default when Lens Detection is set to on but no lens is actually detected, or is this just something weird with my camera? 

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[pippy]

My first suggestion would be to give both the rear surface of the lens-mount as well as the 6-bit code reader on the body a thoroughly good clean and see whether the results afterwards are the same.

Philip.

[roelandinho]

7 hours ago, pippy said:

My first suggestion would be to give both the rear surface of the lens-mount as well as the 6-bit code reader on the body a thoroughly good clean and see whether the results afterwards are the same.

Philip.

Thanks for the suggestion, but for me this is actually welcome behaviour.
 

My most used lenses on the M8 are this uncoded 35 Summicron v4 (for small and light) and a 6 bit coded 35 Summilux Asph pre-FLE (for more light gathering and nicer image quality). If I put on the Summilux it is also correctly recognised so the reader is working (it’s not stuck on v4 Summicron). If I switch back afterwards to the uncoded Summicron it recognises that lens again. So I like the behaviour and don’t want it to change, I was just wondering if this is normal. 

[pippy]

1 hour ago, roelandinho said:

Thanks for the suggestion, but for me this is actually welcome behaviour...

Oddly enough I understand your reasoning.

A short while ago I found myself in the situation where a body, for no apparent reason, started to 'identify' an old (1953) 50mm f1.5 Summarit as one of the recent 50mm f2.5 Summarits. As handy as it was for lens-recognition this new behaviour shouldn't have been / couldn't be possible.

Although I had thought that both lens-mount and code-reader were clean it transpired that there must have been a small amount of 'gunk' on the mount (the reader was correctly identifying coded lenses) and after giving the flange a thorough clean the lens was once more 'unknown'.

FWIW I had an M8.2 and (as might be expected) it wouldn't recognise uncoded lenses. If your camera 'knows' the Summilux then don't clean the Summicron!......😸......

Philip.

[evikne]

2 hours ago, roelandinho said:

Thanks for the suggestion, but for me this is actually welcome behaviour.
 

My most used lenses on the M8 are this uncoded 35 Summicron v4 (for small and light) and a 6 bit coded 35 Summilux Asph pre-FLE (for more light gathering and nicer image quality). If I put on the Summilux it is also correctly recognised so the reader is working (it’s not stuck on v4 Summicron). If I switch back afterwards to the uncoded Summicron it recognises that lens again. So I like the behaviour and don’t want it to change, I was just wondering if this is normal. 

For my M10 this is normal behavior, because you can select an uncoded lens from a list in the menu, and every time you attach an uncoded lens, the camera will remember it. But this should not be possible on your M8 (I recognize two LUF members in this old thread from another forum 😉).

https://www.photo.net/forums/topic/236477-is-it-possible-to-enter-m8-lens-info-via-menu/?do=findComment&comment=2485914

[adan]

13 hours ago, roelandinho said:

Could it be that this lens is the default when Lens Detection is set to on but no lens is actually detected...... 

No.

The "uncoded lens default EXIF" from the M8/9 is: a fictitious lens of "blank" focal length and f/1.0 max. aperture.

I know it well - I have about 30000 M8/M9 pictures made with uncoded lenses, that show that reading. 🤪

However, in some cases, one of the 6 screws on the back of an uncoded lens's silver mounting flange can acquire dark grime in its countersunk depression,and "appear" as a 6-bit dot to a digital M's lens detector array, because it is in just the right position. And being in a screw depression below the surface of the flange  ---___--- it can stay there forever, unless intentionally removed by cleaning the lens mount thoroughly.

Most usually, the lens involved is the 90mm f/2.8 Tele-Elmarit-M v.2 - or any 90 that has a dirty screw in the right place (which will be also detected as a "90TE f/2.8 v.2," regardless of which 90 it really is, and what the real max. aperture is). Because that lens has a single black dot as its code.

More complex lens codes (like ••••••) are harder to "fake" with dirt.

(For reference in this discussion, the actual lens code patterns can be seen here: https://lavidaleica.com/content/leica-lens-codes )

However, that brings up a factor not already mentioned here. The detecting of lens type in the M8/9 depends on two things about the lens. The B&W 6-bit dot pattern - and also the framelines which that lens brings up (detected by a microswitch attached to the manual frame-line selection-lever mechanism).

A 135 or 35 or 50 or 75 will never be detected as a 90 - wrong framelines. However an uncoded 28mm lens (whose framelines are paired with the 90mm lines), or uncoded 21mm (which shares the setting and flange, even though it shows no lines in the finder) will sometimes appear in M8/9 EXIF data as........a "90mm Tele-Elmarit-M f/2.8 v.2"

If they have the right dirty screw.

Correct flange, correct pseudo-dot of grime - the camera doesn't know any better. 😃

And yes, it is "welcome behavior" when it occurs  - if one happens to be using an uncoded 90 of any kind, with grubby screws. At least the right focal length shows up in EXIF.

Edited April 9, 2024 by adan

[roelandinho]

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31 minutes ago, evikne said:

For my M10 this is normal behavior, because you can select an uncoded lens from a list in the menu, and every time you attach an uncoded lens, the camera will remember it. But this should not be possible on your M8 (I recognize two LUF members in this old thread from another forum 😉).

https://www.photo.net/forums/topic/236477-is-it-possible-to-enter-m8-lens-info-via-menu/?do=findComment&comment=2485914

Indeed, the menu for manually selecting lenses was added from the Leica M9 onwards. For the M8, only coded lenses should work.
 

Perhaps I am just very lucky to have dirt on the detector in such a way that it “recognises” the uncoded v4 Summicron and also recognises the coded Summilux pre-FLE when it is attached… 

[roelandinho]

43 minutes ago, adan said:

However, that brings up a factor not already mentioned here. The detecting of lens type in the M8/9 depends on two things about the lens. The B&W 6-bit dot pattern - and also the framelines which that lens brings up (detected by a microswitch attached to the manual frame-line selection-lever mechanism).

Thank you for this. Interesting, I didn't know the frame line selector lever was electronically connected. 

The code for the 35 Summicron v4 is ••••••, which should also be easy to accidentally register if there is a "wide (i.e. around the length of 2 bits)" dark spot in the right place. 

[jaapv]

2 hours ago, jerrybro said:

It's pretty normal for cameras to have fallback options like that, you know, just to make sure things work smoothly, especially with lenses that are popular like the Summicron v4. Your camera sounds pretty clever in that department.

I'm afraid it is not a fallback option but a freak coincidence.