[joachim]

[quote name='Brightcolours' timestamp='1291906406' post='4906']

The basic design may be the same, but they are different in detail. Also notice the reversal of focus and aperture ring between the two designs.

SL (II): 0.5m MFD

M-mount: 1m MFD



(showing the basic design to be the same





[/quote]



Hi,



Thanks for replying to my post.



I am writing about the glass, and that is essentially all Klaus is testing (unless the barrel is not holding the glass in the proper place).



Have a look at what you posted - the optial designs look the same. For sure the barrels (the brass stuff) are different. The close focus is part of the brass stuff, the SLR lens has a longer helicoid. If you study the various incarnations of 90/2.8 for Leica M and R over the decades you will learn that they sold the same glass for both systems.



Considering the differences you point out in the brass stuff, you can point out similar differences between old Nikon AF-D and Canon EF:



mechanical AF vs motor in lens

mechanical aperture vs electrical aperture

aperture ring vs aperture control in body only



Still everyone would have been surprised if a lens available in both mounts (e.g. Tamron) would perform extremely differently between the two mounts.