In this reply I'm concerned with sharpness only...
IIRC, there used to be a time when the FA50/2.8 macro was lauded as the sharpest.
But to be honest, I have no idea which among the 30 odd Pentax lenses (including that FA50/2.8 macro) that I have owned throughout the years really was the sharpest.
AFAIK a "normal" fixed focal length lens is the easiest to design and as such easier to perfect, so I would assume lenses with a focal length in the approx 40mm to 50mm range to have a better chance to be optically the best. This is in line with the FA50/2.8 macro's reputation, but also with statements of the FA43/1.9's and DA*55/2.8's excellence (and even the DA40/2.8).
Longer lenses (DA70, FA77, ...) often have better perceived sharpness. Note however that perception of sharpness is related to the contrast between the in focus part of the image and the out of focus part of the image. And since longer focal lengths have shorter depth of field and therefore more obvious bokeh, the sharp part of an image will *look* sharper by comparison. Comparing the sharp part of such an image with the sharp part of a shorter focal length image will yield much less difference than what the human mind thinks to see...
The now "normal" fixed focal length lenses are moderate wides of old, and have a more complicated design which is inherently more error prone. The FA31/1.8 has the best reputation, however I believe the DA35/2.8 macro certainly gives it a run for its money when it comes to sharpness. Coincidence that it's a macro?
Wim
Last edited by Ishpuini; 01-20-2011 at 07:19 AM.