From what I see the Irix performs very, very well on the K-1. I have no personal experience, though.
Originally posted by pixelvandal To be honest I was leaning towards the 10-17. Even though it's not FF compatible, it's just so much fun!
It covers FF perfectly well from 15 to 17mm, has a slight vignette at 14mm - and needs severe cropping by the time you reach 10mm. But still, 15mm fisheye is seriously wide on FF.
Originally posted by hcc An alternative worth to consider IMHO is the DA15mm Ltd. It is a winner on the K-3 and I read posts suggesting good results on the K-1. The lighter weight and the AF might make a difference....
On APS-C it is definitely a winner. It's so tiny that there's never a reason not to bring it. Wonderful contrast and flare resistance. A gem of a lens.
On the K-1 it requires quite a bit of cropping. You can get a bit more than APS-C size out of it, but not nearly the full frame of the K-1. Shooting in 1:1 crop can work reasonably well, I think, but I still prefer other lenses for wide work on the K-1. (My compact alternative for ultra-wide on FF is the old A20/2.8.)
So, even though I have never used the Irix, I know I will not give up the 10-17. It's very wide for being so compact and light.