Originally posted by Merv-O Torashi, as requested here a few random pics from the IRIX 15mm....
Ok, can you please tell us more? I want to know what you are seeing in those pictures. It might be different from what I see.
I can't see the EXIF data on my phone. If you could include the info (mainly aperture used), that would be very helpful.
Please read this after the above:
It's really hard to judge a lens if I can't handle it and take it through some paces aka stress tests. What I can see and tell you, is that at larger apertures, the depth of field is thinner than you think. Even if it's an UWA (which makes it even harder since everything is so small across the viewfinder). I've noticed this with mine. If I don't absolutely nail focus, it will show. A viewfinder magnifier and/or live view are immensely helpful.
Also, check your mount. There is one design flaw. I though mine was misaligned since one side was blurry. Turns out the mount only has three screws vs. five Pentax always uses. So mine got unscrewed, so I solved it with a tiny bit of thread locker before I screwed them back in tight (but not too tight!).