Another plus to the earlier version is that the optical head unscrews and (important:after removing and carefull storing the rear baffle) can be attached to the 16464 focusing mount...then either used on a Visoflex, or by adding a 14167 M-to-R adaptor used on a Leica SLR, or by adding still another adaptor, used on a Canon EOS film or digital SLR. BTW it's one of the sharpest lenses I've ever owned...got mine in "bargain" from KEH for I think $250, looked like something I'd call LN-.