LTM - M adaptor rings - Advice Please

[ImpMan71]

Hi,
Please can anyone tell me why these rings have different lens focal lengths stamped on them? Are they not interchangeble?
I have a Leica one which has different focal lengths for M2 & M3.
I will be using them on my Bessa R2. Is it ok to use the voigtlander 50mm one on a 35mm lens?
Thanks for any advice,
Colin

 

[photodog]

With a Bessa R2, using an improper adapter will not matter as the R2 has a frameline selector on the top of the camera.

 

[erikhaugsby]

The adaptors are all work in the same way, but give different framelines for different cameras. On Leicas, the framelines are selected by a registration peg on the adaptor, so one that says "50" on it will show the 50 frameline; as the M3 does not have a 35 frame, it will show the widest frame it has (50) by default.

On Bessas the framelines are manually selected by means of a switch, so the frameline registration on the adaptor has no bearing on which frameline will show in the viewfinder.

Hope that wasn't too confusing.

 

[ImpMan71]

Thank you both - it all makes sense now.
I wondered if they were different thicknesses, but couldn't see how as when used on a screw mount camera they would be in the same place.
Thanks again,
Colin