I have shot some of my lenses wide open and a few at f32. The 45-85 at 45mm f32 looked good enough for a large print but there was diffraction that was visible when zoomed 1:1. Truthfully at f32 the images look about the same as my Canon 5d MkII zoomed in because of the AA Filter on the Canon.
The only lenses I have shot wide open are:
150 F2.8 - My copy of this lens is very sharp wide open...however its got some really bad CA
120mm F4 - Looks great wide open
55 f2.8 - Looks great wide open as well
My shots wide open have been portraits done mostly outside, so I have haven't bothered looking at corner sharpness when shooting wide open. In the center the 3 I have used look awesome with the exception of heavy CA on the 150.
Thanks for your response. My previous comments about FA lens performance was commenting on the almost entire line of FA lenses and multiple samples of each...so the # of test samples would be at least some representation of what performance characteristics are like on the 645D body. It's not so much only looking at corner sharpness, but performance across the entire frame from wide open to stopped down till approx f13 (and slightly beyond). With this testing, there was enormous variability among samples of the same lens and of course variability seen with many of the FA lenses in general. This was especially seen when comparing samples of the same lenses from wide open to 2-3 stops down from max. aperture. Of course once you stopped down most any of these lenses to f13 and smaller, differences become less. I will have to preface my comments thats I was examining all shots at 100% (actual pixels), since my output is to large format prints and looking at 100% crops is the only way to determine if a image is of sufficent quality to print large. Before any real testing, I determined best Af fine tune for each sample of lens on the 645D. One thing I can say is the 120 maro is the most consistant performer on the 645D...each sample tested performed almost identically optically to the next, once minor AF fine tuning was performed on each.
Unfortunately quite a few FA lenses in general showed moderate to high levels of CA...but it must be kept in mind, most of these lenses were developed prior to the days of Pentax MF digital, and so their design and coatings weren't designed for it. As you mentioned the FA 150mm f2.8 shows a fair amount of it and the FA 75mm f2.8 showed a lot! Still all in all, good samples of these FA lenses had admirable and often times excellent and better performance when used on the 645D.