What Kostas says is correct, but there are 4 possible "advantages" to getting a Spotmatic as opposed to a KM. 1st, the Super-Takumars and the SMC Takumars tend to be less expensive than the K mount lenses. Second, in my view the build quality or feel of the old screw mount lenses is better than the (still very excellent) K, M, and A lenses. Third, Spotmatics are pretty cheap. Finally, you might like the aesthetics of the Spotmatics more than the KM, etc.
I have a couple of Spotmatics and I continue to use them even though I have more recent Pentax SLRs (K1000, LX, and MX). Aaron Bransky >>>>>Can I make a suggestion? People who have had and cherished both, suggest that the early bayonet cameras are late Spotmatics with a different mount; the KM is I think is mentioned as a prime example. http://kmp.bdimitrov.de/bodies/K/ The advantage of these cameras is that they work with the vast majority of Pentax bayonet lenses produced even today. With an adapter they also accept screwmount lenses (in stop-down metering mode). Just a thought, Kostas<<<<<<
