[JJ_SO]

• I like f1.2, or even more f1.0 (but that is too expensive). Why? For DOF freedom. 
• A Canon 6D/5D mkIII/ 1D-X has no problem focussing a Canon EF 50mm f1.2 L USM.
• My Nikkor-S*C 55mm f1.2 is sharp enough at f1.2. It is also contrasty enough when not shooting against backlight. My Canon FL 55mm f1.2 gives very nice flares against back light/low sun, something many photographers will appreciate. A reason to keep it as specialty lens, for sure.

Yes, I have an idea why. Nikon F-mount diameter is too narrow to make a real f1.2 lens. All the 58/55/50mm f1.2 lenses Nikon has made have had trouble with this, with extreme cats eye highlights/bokeh discs as a result and because of that also a lot of loss of light. And swirling bokeh. There simply is not enough room mount-wise for f1.2 for a standard prime. 

The Canon EOS mount diamter is a lot larger (54mm vs. 44mm), providing room for bigger back elements. Both my 55mm f1.2's have way too small back elements. The difference to the Canon EF 50mm f1.2 L USM is big (and very noticable).

 

For Zeiss it is the same situation. If they were to design an f1.2 with large enough back elements, it would not fit Nikon F-mount. And Zeiss does not design EOS mount only lenses.

Excellent points, Brightcolours!


Is that also the reason why Canon has 85/1.2 and Nikon don't? I recall Zeiss making such a lens for Contax years ago in a limited edition (wooden case and everything, so probably not much of those lenses have seen some film surfaces behind them).


Still, not my cup of tea, those large apertures. For me f/1.4 is alright, I learnt how to handle those and guess f/1.2 is much harder for getting the focus right. At least with Nikon AF, I think Canon makes better ones.