So far with these M lenses I either own (or recently rented) with UT Kolari mod A7r2 (w/notes)...*=winner
35/2 Summicron Canada v3: Very good when cropping to 645 in post, f/2 - f/9
best to crop to 645. corners at full 3:2 almost clear at f/9, f/11 good on tripod at base iso 100ish
35/2.8 Zeiss ZM: good corners at f/4 - f/11, good lens w/UT mod but not as sharp/good as Voigt 35/2 Asph Lanthar M mount
35/3.5 CV Color Skopar: iffy and ok for $300 lens, but would rather have v3 35mm Summicron if a choice. I think this would be
alot better on M film (same w/v3)
*15/4.5 CV Asph good at all f/4.5 - f/11, outstanding on A7r2 mod.
far better than Tri-Elmar at 16mm on Sony UT mod, while 21 no comparison to 21/2.8 Loxia on Sony non-mod
(Loxia 21/2.8 not good on UT mod, smeared edges/corners)
15/4.5 CV pre-Asph: not good, not recommended
25/2.8 Zeiss ZM: good at all from f/2.8, best at f/5.6 - f/8, exc on my A7r2 UT mod, makes me consider selling Q (but no won't do that)
35/4 CV Snapshot Skopar LTM: not good, not recommended on full-frame digital. (good on Sony Nex7 apsc)
90/4 Minolta/Rokkor: not recommended on full-frame digital. (Good on Sony Nex7 apsc)
rented Tri Elmar 16-18-21: not as good as CV 15 on Sony A7r2 UT mod, would never pay $4k to use on Sony (vs what others have said likely without using it), not great at 21 on Sony, but great lens on M10 at all apertures/focals 16 and 21 good on M10 and if I was keeping M10, would buy lens all day.
rented CV 35mm f/2 Lanthar: outstanding from f/5.6 to f/11 for landscape (f/16 not good)