Help me understand the need of F2.8 in such a lens.
I would think, that at 10mm, this lens will be mostly used as a landscape/architecture photography tool, and for that you will need the biggest DOF. Of course, at 10mm even 2.8mm will you give great DOF, but i will doubt that anyone will use it due to softness.
So why is it F2.8? so you could handhold shoot at night some buildings? (Most would still use tripod and bigger F stop anyway)
For Astrographers so they can have less exposure time and less noise in the end. I guess.
Manual Focus without a proper manual focussing screen wont be hard with that lens i hope. Im having a hard time with my 28mm f/2.5 lens already. Anything else 35+ works fine manually focussing (m42 lenses, no af chip)