Q.G. de Bakker , Feb 14, 2005; 11:48 a.m.
There are two versions of the CF 50 mm Distagon.
The first is the same lens as the C 50 mm Distagon, but in a new shutter and barrel. There will be very little or no difference in performance between the two.
The second CF version was the same as the current CFi 50 mm Distagon: a new design, using floating elements (FLE) to improve performance in the corners of the image, especially at short focussing distances. The difference in performance will be visible, mostly at large apertures.
The C lens has a threaded mount. It takes series 63 drop in filters, which are held in place either by a screw-in retaining ring, or by the round screw-in lens hood.
Only the CF lenses have bayonet 60 mounts (the CFi has bayonet 70 mount, taking larger filers so you can stack mre than one, or use thicker ones, without vignetting).