Fast 50mm
This is certainly the place where the Pentaxian is spoilt for choice.
There are so many fast 50mm to choose from.
K50/1.4, K50/1.7, K50/2
M50/1.4, M50/1.7, M50/2
A50/1.4, A50/1.7, A50/2
and the
FA501/4
just from Pentax alone.
Optically they are all good. Just pick your preference and budget.
I've tried all the M and A series (from f1.4 to f2) and they are all good. Use a hood to improve contrast, esp. when wide open.
The f2 ones are just a bit smaller and lighter, which is why one finds its way on my camera when I choose to use one.
The 'A' version is the most convenient to use for not much more money.
You get to use multi segment metering, PTTL flash, EXIF data on aperture, Av mode control.
However, I somehow like the 'M' versions more as they are very slightly smaller, feel better to MF and nicely built.
I find that if I am given my own peace to walk about and shoot small things that catch my interest, a lens about the focal length of a 50mm would be my prime choice (actually 43ltd is the best choice for me
).
Small, light, fast, DOF control and sharp when needed. Very effective on small object imho.