f8.0.
Fred wrote:
It's very good, it follows the usual Pentax normal lens
characteristics, a bit soft, (by prime lens standards), wide open.
Very sharp when stopped down to 5.6 or 8.
I would basically agree, but I would say that the very high sharpness starts at f/8. My impression is that the 55/1.8 is only average up through f/5.6, but then it does become "super-sharp" ~all-of-a-sudden~ at f/8 and above - perhaps the most "schizophrenic lens" I've ever used - <g>.
http://www.cetussoft.com/pentax/resolutn.htm
Fred
