Adapted lenses on Leica SL (Typ 601)

[LCM94]

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Hello,

As mentioned in my other thread, I have several vintages lenses for which I bought an adaptor:

- Pentax 28mm f/2.8

- Pentax 50mm f/1.2

- Minolta 35mm f/2.8

Seems that my Leica is guessing or calculation somehow the aperture value even though there are no contacts of course on these lenses.

It is pretty inaccurate though.

Do you report the same?

Thanks

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Edited May 4 by LCM94

[BernardC]

19 minutes ago, LCM94 said:

Seems that my Leica is guessing or calculation somehow the aperture value even though there are no contacts of course on these lenses.

It is pretty inaccurate though.

Do you report the same?

Yes, it's a well known thing.

There's a light sensor on the body of the SL which is used for this calculation (top right when viewed from the front). The camera compares ambient light levels with the levels coming through the lens, and guesses the aperture.

The aperture estimate is used for lens correction on M lenses, because some corrections are aperture-dependent (for instance: vignetting). Even then, the aperture value doesn't need to be 100% accurate.

That's all that the aperture information is used for. Maybe Leica should have created a different/hidden field in the EXIF for "estimated aperture."

You may wonder how the SL comes-up with numbers like F:1.0 when you have a humble F:2.8 fitted. It's because the on-body meter was shielded, so the camera thought you were getting a lot of light from a dark scene. It doesn't really matter in the end, the number is ignored by the software.

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[LCM94]

Thanks a lot for this thorough explanation 👍. Indeed when testing f22 I was getting on the exif something like f32 😀
I don’t mind the incorrect values these lenses are very special. I just thought that the camera had an issue or that the lenses were off in their real aperture values. 

Edited May 4 by LCM94

[mark harverson]

I had a moment after your comment when shooting my FE Auto-Topcor 35mm on my SL. See pic. Lol just realised I had a PL

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filter on the lens. Idiot!