does the Leica branded R to SL adapter apply aperture-depedent adjustments

[cpclee]

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ROM contracts supply information about what lens it is and what aperture is being used.  There was an article specifically about this in LFI years ago, and the aperture information was used by the R8 / R9 to adjust metering reading to account for vignetting for some lenses at wider apertures.

 

In theory, the Leica branded R to SL adapter should be able to do this as well.  Meaning in addition to applying a lens profile, the SL should be able to apply aperture-dependent adjustments to counter vignetting.   Has anyone actually seen this work?  

[LD_50]

How would you “counter vignetting” with a meter reading? Would that not simply brighten or darken the overall image by changing the shutter speed or ISO?

 

You can do this now with an SL with exposure compensation in real time.

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[scott kirkpatrick]

Unfortunately, not all of that function was implemented in the Leica R adapter-SL.  I just tested it with an 80 SX-R.  It recognizes the lens model but does not show the aperture setting, although it writes an estimated aperture in the EXIF data (it estimated f/3.5 just now but actually I was set at f/5.6).  With some of the R zooms, it will report the current focal length, and uses that information in distortion corrections which are included in the DNG file or used for in-camera JPEGs.

 

Leica is not currently making visible any aperture information that is not originated in the camera (as with SL, TL, and S lenses).  That way the information doesn't have to be read from the lens over the electrical contacts.  And with the aperture estimated by comparing an outside with an inside exposure reading, they seem to hide it.  It now shows only in EXIF (since firmware 3.0).

 

Vignetting is aperture dependent, seen most strongly at wide open apertures, and usually no longer present when the lens is stopped down 4X or more.  Leica's in-camera profiles do apply vignetting corrections across the image, but they use the estimated aperture for this on M and R lenses.  You can observe this happening by putting a finger over the blue spot on an M or the little window on the left hand corner of an SL.  This makes the camera think it is very dark outside yet there is still a bright image, so it chooses the widest aperture.

[cpclee]

This was mentioned in the LFI article I mentioned.  It means the meter would know that the corners are naturally darker by a little and would adjust its reading to account for that (to avoid overexposure).  

 

How would you “counter vignetting” with a meter reading? Would that not simply brighten or darken the overall image by changing the shutter speed or ISO?

You can do this now with an SL with exposure compensation in real time.

[cpclee]

Thanks for the details.  I should test the vignetting compensation myself.  I'm surprised that the ROM contacts aren't utilized in getting the aperture.  One would think that's better than estimating.  Perhaps this is because Leica wants a universal way to handle R lenses whether they have ROM contacts or not.

 

 

 

 

Unfortunately, not all of that function was implemented in the Leica R adapter-SL.  I just tested it with an 80 SX-R.  It recognizes the lens model but does not show the aperture setting, although it writes an estimated aperture in the EXIF data (it estimated f/3.5 just now but actually I was set at f/5.6).  With some of the R zooms, it will report the current focal length, and uses that information in distortion corrections which are included in the DNG file or used for in-camera JPEGs.

 

Leica is not currently making visible any aperture information that is not originated in the camera (as with SL, TL, and S lenses).  That way the information doesn't have to be read from the lens over the electrical contacts.  And with the aperture estimated by comparing an outside with an inside exposure reading, they seem to hide it.  It now shows only in EXIF (since firmware 3.0).

 

Vignetting is aperture dependent, seen most strongly at wide open apertures, and usually no longer present when the lens is stopped down 4X or more.  Leica's in-camera profiles do apply vignetting corrections across the image, but they use the estimated aperture for this on M and R lenses.  You can observe this happening by putting a finger over the blue spot on an M or the little window on the left hand corner of an SL.  This makes the camera think it is very dark outside yet there is still a bright image, so it chooses the widest aperture.

[LD_50]

This was mentioned in the LFI article I mentioned.  It means the meter would know that the corners are naturally darker by a little and would adjust its reading to account for that (to avoid overexposure).

 

That’s what I mentioned, it would simply adjust the exposure. I can’t see that being incredibly useful.

 

Matrix metering should already account for this in the SL. Or simply adjust manually or with EC.

 

The full electronic transmission mentioned by Scott Kirkpatrick I would see as useful for automatic correction via lens profiles.

[Leicaiste]

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Thanks for the details. I should test the vignetting compensation myself. I'm surprised that the ROM contacts aren't utilized in getting the aperture. One would think that's better than estimating. Perhaps this is because Leica wants a universal way to handle R lenses whether they have ROM contacts or not.

On the R8/R9 the ROM could not transmit the actual aperture in use. That information was transmitted by the moving R cam. As there is no reading cam on the Adapter to convert the mechanical information in digital information, the SL and M can only guesstimate the aperture. Edited September 27, 2017 by Leicaiste

[cpclee]

I see. But the contacts can communicate the focal length being used on a zoom so somewhere behind the rom contacts there is still some sort of mechanical linkage?

Edited September 27, 2017 by cpclee

[scott kirkpatrick]

I see. But the contacts can communicate the focal length being used on a zoom so somewhere behind the rom contacts there is still some sort of mechanical linkage?

I was told by an R expert that the information about the focal length was passed to the electronic flash, in order to adjust its spread angle.  Don't know how they did it and I don't know if this also worked with cammed lenses (non-ROM).

[Leicaiste]

I see. But the contacts can communicate the focal length being used on a zoom so somewhere behind the rom contacts there is still some sort of mechanical linkage?

Or electronics.

 

By the way, the ROM R Extender 2X transmits the resulting focal length when used with ROM R lenses on the R8/R9 but not on the SL.