Originally posted by henryjing I think the IQ is more important than a small F value for a lens. For some lens, though they got the maximum aperture as 1.4, but always we use it at 2.8 for a sharp shot and beautiful bokeh. So I think I would prefer those lens with smaller aperture, but they can do pretty well at maximum aperture. For example, I prefer DA 35 than FA 35, DFA 50 than FA 50.
Interesting point! I recently sold my FA 50 because although it was a 1.4 aperture, wide open it was very soft and lacked contrast. (Maybe just sample variation, who knows?) Sure, it was VERY sharp,
stopped down, but at least for me, that's not the purpose of fast glass!
Another couple threads have questioned FA 50 vs. DA*55 vs. Sigma 1.4 HSM. Personally I'm not too keen on the price of the DA*55, but from what I've read, the Sigma has been designed for improved performance
at maximum aperture. I think Pentax missed the boat with the DA*55 because for most people, paying at least twice the value of an FA 50 does not equate to twice the image quality (recent bokeh examples not withstanding!).