New to this forum and rather new to Pentax equipment (1.5 years).
I currently own 3 Pentax-M lenses
35/2.0 - My favorite, normal lens on my K20D, sharp at 2.0, razor sharp at 4.0.
50/1.4 - Could be my copy, but the lens, although beautifully mechanically made, is extremely soft at 1.4, still soft at 2.0 and really getting sharp above 2.8. I use it from time to time, but it fell from grace once I got the 35/2.0
150/3.5 - very pentax-like to make this bizare focal-length lens (for 35mm system). Got it because I wanted a telephoto and was/is on a very tight budget. Contrast is a bit lacking and pictures are often washed-out, but once I got to know its limitations, it gives me a lot of reach for $80.
50/1.4 sample stopped down
50/1.4 sample at 1.4
150/3.5 samples
35/2.0 samples (both low-light, hand-held)