adaptor ring

[kengai]

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which ring to use the old screw lenses, such as the Summaron 5.6 / 2.8 cm, on an M-P body?

[jaapv]

Nearly any LTM adapter will do Voigtlander makes nice ones. Get a codeable one. Old Leitz adapters may not be recognized by the camera because of the cutout. Make sure you buy the right focal length adapter, although this will only influence the frameline selection.

[250swb]

The above +1

 

I get mine from Ebay but the main thing is to get one that can be coded, then even if you don't code it you know the cutouts will be in the right place.

[bocaburger]

Make sure you buy the right focal length adapter, although this will only influence the frameline selection.

Did this change with the M240/M-P?  I thought they used the 6-bit coding together with frameline cam position to determine which lens was in use, as the M8 and M9 did. 

[ayewing]

I have always understood that the frame line selection was a purely mechanical process not involving electronics and largely unchanged since the days of film cameras.

[pop]

I have always understood that the frame line selection was a purely mechanical process not involving electronics and largely unchanged since the days of film cameras.

So it is, but the processor in the camera senses the frameline that has been selected and uses this information to determine - for example - the focal length selected in a tri-elmar. Or so I'm told.

[microview]

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I think Voigtländer LTM adapters are now discontinued, although they were excellent. Red Dot (London) shows some Chinese made alternatives on its web pages. And Rayqual are current although I had one once where the tolerances were out, affecting focus accuracy.

[jaapv]

Did this change with the M240/M-P?  I thought they used the 6-bit coding together with frameline cam position to determine which lens was in use, as the M8 and M9 did. 

The frameline selection is mechanical, however, the position of the frameline is taken into account together with the six-bit coding to determine the lens mounted. As pop says, this is done to sense the three positions of the MATE. Additionally it multiplies the number of lenses that can be recognized.

[jaapv]

Did this change with the M240/M-P?  I thought they used the 6-bit coding together with frameline cam position to determine which lens was in use, as the M8 and M9 did. 

Yes, but most users do not code for LTM lenses as they are not corrected - or even listed- in the firmware.

[bocaburger]

Yes, but most users do not code for LTM lenses as they are not corrected - or even listed- in the firmware.

Ok, I get you.  You said "get a coded one", which threw me off.   The OP did mention 28mm, so even if he didn't code it he might want a 90mm adapter to call up the 28mm framelines.  With a codable adapter and proper frameline camming for the focal length, he could experiment around and maybe there would be a firmware code that would put "28" in the EXIF (and LCD) and do a respectable job of correcting.  I found ones for my 21, 28 and 35mm CV lenses that work well.  Back in the M8 days I bought up a bunch of the old Leitz 9cm adapters without cutouts and used them for all my CV and Leitz-LTM lenses and a 105mm Nikkor.  The 90mm cam is the longest, so it's no problem to file them down to bring up 50/75 or 35/135 if wanted.