[QUOTE=KjetilH;358014]Has anyone got both the f/2.8 and f/3.5 version of the M28?
The 3.5 is generally regarded as a better lens, but is the difference anything noticeable, or rather "not correctable by setting the camera to a bit extra contrast"?QUOTE]
I tested an f2.8 against an f3.5, and there was a small sharpness difference at comparable apertures (f3.5 better at f3.5, a hair better at f4). But it wasn't enough to show up in a real-world photo, and not enough to sell one to acquire the other (in my opinion). The f3.5 front element is flatter and easier to clean, though.
Someone mentioned the A 28mm - if the A really is for wimps
then you can search for the M28/2.8 version 2. It can be easily spotted, even in a bad eBay photo, because the serial number is not engraved on the name ring.