f stop recognition in Lightroom.

[dbeids]

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Using the M10-r with new (coded) and old (manually entered) Leica glass, I’ve noticed that Lightroom 4 isn’t recognizing the set aperture correctly. Not sure it actually effects the final result, but I’m curious about why that is. Anyone else notice this?

[Sailronin]

It's my understanding that with no electrical connection between lens and camera, EXIF is extrapolating the f-stop based on shutter speed, ISO and the resulting image "density" so it will be an approximation at best.  At least this was the case with my M9, the new CMOS cameras may have a completely different algorithm.  This will not impact final image quality at all in post processing via Lightroom, PS, Capture One, etc.

Someone please let me know if I'm way off base in these assumptions.

[dbeids]

Thanks for the helpful response. 

[Jeff S]

Frequent topic…

Six bit coding has nothing to do with it.

Jeff

[dbeids]

Thanks

[Camaro5]

The aperture "guess" displayed in Lightroom was added only with the most recent firmware update.  I was not seeing it at all before the update.  I know it's determined by an algorithm and sometimes it's close or right on, and other times it's off by a mile.   

The other day I purposely took a shot at f/11 on my M10 and Lightroom showed it as something like f/6.8 which is kind of odd.  It was a high contrast scene.  It seems like the more even the light is in an exposure the closer the aperture calculation is in the Lightroom display.   

I suppose it's nice to see the aperture in Lightroom but if the calculation is off by so much most of the time it's really kind of useless information.  

[Jean-Michel]

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Lightroom is not guessing anything at all. The f/stop approximation/guess is done by the camera. Do you see that little round window at the top front of the camera? That is the brightness sensor that the camera use to compare  with the ISO and shutter time used to estimate the aperture used. It is never accurate, has zero effect on anything and is really quite irrelevant.