2.0 Firmware Bug?

[Captain_EO]

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I updated my SL to the 2.0 firmware last night. Now all of my M lenses are getting an incorrect aperture reading the camera. In manual mode the aperture reading is jumping around depending on the available light. If I put the lens cap on it jumps to F16, if I point it directly at a lightbulb it jumps to F1.4. Obviously the camera body isn’t adjusting the M lens aperture, but the reading on the camera is changing and recording incorrect values in the EXIF. 

 

Is there anyway to revert to the previous firmware so I can rule out if its a hardware issue or not.

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[dkCambridgeshire]

Are they 6 bit or non-6 bit M lenses?

 

dunk

[digitalfx]

The aperture is an estimate only. There is no way for the camera to know the exact f stop

[Captain_EO]

Are they 6 bit or non-6 bit M lenses?

 

dunk

 

They are 6 bit. I never had this problem on my M240 or the SL until I updated to the 2.0 firmware. 

[jonoslack]

How far out is the Aperture reading?

[trond]

With the Summilux 28 it is pretty darn close.

 

f1.4 reads f1.7, above that, each and every half stop is exact up to f16.

 

Best regards

 

Trond

[ramarren]

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I tested with coded 'Lux 35 v2 and Summarit-M 75 lenses, trying to replicate your reported behavior and see if there was any difference from the R lenses I've been using. I was unable to obtain any unusual behavior—the SL reports aperture used with either R or M with exactly the same accuracy as it did before: presuming that I don't accidentally put my finger in front of the external sensor, it's usually within 1/3 stop of the actual setting. 

[Sandokan]

I always had 'problems' with the M240 too. It was rarely accurate for the actaual f stop used. Maybe the IR filter I have on all lenses had an impact? 

[ramarren]

Since any adapted lens on these cameras has no way to tell the camera specifically what aperture is being used, it's best not to be too picky about what gets written to the EXIF data and realize that it's just an estimate. Coded M lenses produce marginally better estimates of working f/number on the M than the SL does—after all, they're the lenses that the M was designed for. 

 

The SL (and T) lenses, of course, relay precise information about focal length, maximum aperture, working aperture, focus distance, etc etc, to the SL body, so with those lenses the EXIF data will always be precise and exactly on the mark. 

[Captain_EO]

Thanks guys. This is just my own ignorance. I didn't have a complete understanding of how 6 bit coded lenses work and never noticed the inaccurate readings before. Sorry for the red flag!

[Suteetat]

I never had accurate F stop reading with my old MM240. SL was the same but I agree that there is a difference after fw2. I notice after the update that F stop is jumping up and down quite a lot while I was taking pictures yesterday with R lenses. In the past, I don't recall seeing F number changes in view finder so often but then again, in the past, I never paid any attention of F stop number in viewfinder or LV before when using manual lenses.