http://www.brendemuehl.net/images/comparisons/FA5014CO5514A5014/
Pentax FA 50/1.4
Pentax A 50/1.4
Cosina screw-mount 55/1.4
So why would I compare a 35-year-old Cosina to two modern
lenses? Just for something to d.
I thought it would be interesting to see what any real difference might be.
Contrast
FA @ f2.8 and f11 is the clear winner.
But between the other two, @ f11 the Cosina compares
favorably to the A.
(Though as Shel stated the other day, stopped down even a
coke bottle can be made to look good.)
Even at f2.8 the Cosina had good contrast. Edges on the
center item [last set] were good, but it didn't
have enough of whatever other optical quality was needed to
bring these edges out and make the
final product better.
Color Correction
FA wins, A is very good, but Cosina just doesn't cut it at
2.8, though is good at f11.
Interestingly the Cosina has a yellowish cast, like an old
Tak might have. This could account for some issues here.
