...and its name is f/0.95:
Got the Nokton 17.5mm f/0.95 in for evaluation. I'll have it until next Wednesday. This could be bad. I've wanted to test this lens for a while, but I thought 'it's only manual, and it's expensive, and I really don't need it.' And I'm quickly falling in love. This thing is awesome. Beautifully built, heavy for a m4/3 lens, but smaller than I thought it would be. Relatively easy to focus, and while there is plenty of LoCA at f/0.95, it's really the only flaw at that aperture. It is DARN sharp at f/0.95. In fact, given the aperture, it's amazingly sharp. Stopped down, it's absolutely tack sharp corner to corner. This one's going to hurt to send back. Only got to shoot with it for about 45 minutes today, but I like.
Some samples. I believe all of these are wide open at f/0.95. I did take plenty at f/1.4, f/2 and even further down,but that's not the exciting part of this lens (ok, how sharp it is in the corners stopped down is pretty exciting)...but still
100% crop of above (remember, this is at f/0.95):
And, it focuses REALLY closely (6"):