I love the old spotties though, my meter works about half the time. I have the 50/2, 50/1.4, and the 55/1.8, and cant honestly tell the difference. I use the 1.4 the majority of the time. The 28/3.5 is very sharp, I use it more then any other K-mount lense. The old K-mount "k" series lenses are sharper then the "m", and "a" according to some. I can see no difference there either. The K lenses are alot rarer because the M series came out so soon afterwards andreplaced the K. The K lenses are built more soundly though have the old takumar feel to them. Pentax glass has always done me proud, I just wish people would stop buying the screwmount taks for there dslrs, they are making the prices skyrocket!! The 40 mm is probably one of the least sharp lenses, but as mentioned above it is TINY.