Screw to M Bayonet Adaptor

[petebown]

Which screw to M bayonet adaptor is suitable for wide angle and ultra wide angle lenses? I have a 25mm CV lens but am not sure which adaptor to use on an R3A... Although I'm not sure it really matters as this particular lens is not rangerfinder coupled anyway.

As a matter of interest, does anyone know what the difference is between the three types of adaptor? What would happen if I were to use the wrong one with say the 90mm lens?

 

[pvdhaar]

The R3A has a manual frameline selector, so you can use any of the adapters, beit the 28/90, 35/135 or 50/75.

Only with the Leica M and Konica Hexar RF, the framelines are brought up automatically by a notch that is different between the three adapters..

 

[peter_n]

Cameraquest sells "generic" adapters cheap that are good for lenses like the CV 25, 15 and 12mm that don't rangefinder couple.

 

[jlw]

The only issue I've encountered with generic adapters from various sources is that some of them are too thick, preventing the lens from focusing to infinity. This is a potential problem even with super-wide, scale-focusing lenses, since depth of focus (as opposed to depth of field) is small with a wide-angle lens at infinity.

Some of the generic adapters are fine, but I recommend buying an inexpensive digital caliper (mine was under $10 on sale at Harbor Freight Tool) so you can check the thickness. The correct thickness, as measured off a Leitz adapter, is 0.97-0.98mm. I've had independent adapters that were as thick as 1.02mm!

 

[peter_n]

Good info - thanks jlw!

 

[pvdhaar]

I've had good experience with the Voigtlaender adapters from Cosina. Both the 28/90 and the 35/135 allowed my CV-LTM lenses to focus at infinity (with the RF also at infinity). There may be other adapter brands than CV, but I figured that they'd at least be matched to their lenses.