I have just received my "new" second hand Pentax 50mm 1.7 which I won from ebay Australia. This is my first M lens for my K10D and let's just say i'm pretty excited to get my hands dirty. M lenses without an A setting supposedly have some problems with metering on the K10D but I haven't had a chance to see for myself. Here are some links on the subject;

Pentax Forums - K10D stopped-down metering weirdness

Pentax Forums - k100d stop-down metering problem

Race High's Blog - When the Focusing Screen Lies (for Focusing and Metering)

I'll have a play with this lens over the next few weeks while I'm in Kyoto.

All images taken by ceba1962