Originally posted by mikeSF yeah, i had it on my list
Just finished a comparison I wanted to do for a long time, which remains incomplete, but is nevertheless interesting for what it is and I thought I'd share the outcomes. These are mostly lenses that I have had in my personal possession for a long time, and that I always wanted to compare. Tests were shot on my 645D at 100ASA on a tripod and with mirror up, and images were taken at two F-stops, one fairly wide open, and another at F11.
150mm. I compared two FA versions and an adapted Zeiss/Rollei Sonnar. At F11, one of the 150mm FA lenses did best, better than the Sonnar, while at F4 the Sonnar faired better than the Pentax lenses, which much more beautiful bokeh. Nevertheless, the Pentax lenses had a nice soft touch to them, which made them equally attractive, at least for portraits.
120mm Macro. Tested two A versions and one FA version. One of the A versions did better than the other A and the FA at F4 and F11. The FA and the 2nd ranked A were about equal. Performance at F4 was almost on the same level as F11, and all three lenses outperformed the three 150mm lenses I tested.
75mm. Compared the 75mm FA and an adapted P67 AL. The P67 AL was simply much better than the 75mm FA. The 75mm FA was very soft at 2.8, while the P67 AL was already quite good wide open.
55mm. Contenders were an adapted P67 55mm/4, the A version 55mm/2.8, and the recent DFA 55mm/2.8. In the center, the 67 lens was slightly better than the other two at F11, while it was slightly worse than the other two lenses at F4. My copy of the DFA had remarkably even performance at F4 and F11, and at least in the center, the tiny 55mm A lens was a good match for the new DFA at F11, while the A was slightly inferior at F4. Corner performance of the P67 was top, closely followed by the 55mm DFA. In fact, at F11, both lenses performed at an equal level while at F4, the P67 was slightly better. The 55mm A came in as a distant third in terms of corner performance.
35mm. Perhaps my copy of the A is less than stellar and/or perhaps I have been lucky with my copies of the 35mm FA. In this test the FA clearly outperformed the A version at both F-stops and both in the center and in the corners, and I have been very happy with this version of the FA and a previous version that I sold at the end of the Pentax film days.
I'd be curious to see how the Pentax lenses stack up against some of the other Zeiss and Schneider lenses in my arsenal, but it'll take a while until I get to do another test. I am also not saying that this is the final word - others have published similar tests here, and differences in outcomes likely represent sample variation. Nevertheless, I was glad I found the time to verify lens performance in my own lens stable and thought I'd share the results for everyone's consideration.