Optimized at 1.5. See attached image shot @ 1.5 using an M10-r, with 100% crop. No issues, a great lens. Comes with the optional Zeiss hood. Not happy with it, send it back! (in same condition of course. And not after using it on shoots, trips, spring break, covering a sandstorm, scuba diving, sperlunking, documenting a nuclear test, and a few other items I have yet to imagine)