I wrote earlier about infinity focusing problems. They are real with my K-1 MK2 and they were there already before the modification with Zeiss 50MP. Long story short, after receiving TWO 15-30mm D-FA zooms which were decentered badly, I decided to get my old Irix 15mm lens back. Today I received the lens from the dealer with which I swapped the lenses.
Here are two 100% crops from image center taken from apartment window before and after a little lens modification:
1. Unmodified Irix lens, focused as far as it goes towards infinity
@ f/4:
2. I opened the lens and took out a spacer. Now it reaches infinity
@ f/2.4 and goes even BEYOND!
Suddenly the Irix becomes sharper @ f/2.4 than average copy of 15-30mm zoom wide open @ f/2.8 with unmodified camera. Looks like this full-spectrum system requires major efforts to get things going. Here the spacer I removed was about 1/10mm thick and now I am a happy camper. I don't have the clip-on filter yet. Ordering it this weekend.