There's considerable confusion about the performance of the three classical "rubber focusing" Konica AR 135mm Hexanons, namely the Hexanon AR 2.5/135mm, the AR 3.2/135mm and the AR 3.5/135mm. General opinion seems to be that the f3.2 version is the best ("sharpest"), while the f2.5 is a bit behind the f3.2, and the f3.5 is the worst of them. Most of the information found in internet chats and different forums seems to be based on Andreas Buhls homepage (www.buhla.de). However, there's not too much accurate information derived under controlled conditions to be found online.

Camera: Sony A7 (24MP Full Frame), Quenox Konica AR => Sony E adapter

Tripod: Giotto MTL 8351B Carbon; Head: Manfrotto 410 three way head

Selftimer 10s and electronic first shutter used

Here's the image. Marked in yellow are the three crops which are to be found further down (wide open, at f5.6, and at f11):

Hexanon AR 2.5/135mm

The fast f2.5 Hexanon is slightly soft wide open, and at f2.5 it has considerable CAs. Stopping down to f4 the contrast improves quite much, and at f5.6 the CAs are gone. Because CAs are very well corrected at f5.6, the Hexanon image quality at f5.6 is better than most classical 135mm lenses from other manufacturers such as Minolta, Canon and Nikon (they try to correct their CAs wide open, thus causing visible CAs at f5.6). 

Hexanon AR 3.2/135mm

The slower 3.2/135mm Hexanon has an excellent reputation for its resolution and contrast. Between f5.6 and f11 this lens has a nearly apochromatic correction and the excellent resolution covers the entire field including the extreme corners.

Hexanon AR 3.5/135mm

The slow 3.5/135mm Hexanon is the newest and at the same time the wakest of the three lenses tested here. Of course it was computed as a budget lens. Given its low price the performance is absolutely acceptable. Its main problem are the rather visible CAs, not only wide open, but also at f5.6 and f11.