I would suggest you stay away from the Olympus OM1 or OM1n, simply because of the battery issue (designed to take an unavailable mercury battery)
I have several Olympus bodies (OM2, OM2n, OM2sp, and OM10) and various associated lenses. I regularly use and love them all. ( I have a film in an OM2 right now)
I also have several Asahi Pentax bodies, incluuding S1, SPF, KX, and MX and various associated lenses (which I alternate with the OMs).
The benenfit of the later screwmount (after the Spotmatic II) and the K-mount bodies is they all use the relatively readily available silver oxide 1.5v batteries.
Moreover, in my experience, although somewhat "less sophisticated", the Asahi Pentax bodies are more robust and less trouble-prone than the Olympus OMs. The lenses are equally good, and frequently cheaper and more available.
Overall, I would recommend the Pentax line (starting with the Spotmatic F), for trouble free operation. ( I, personally, would opt for the match-needle metering models , as I find them much more user friendly under a wider range of conditions in the field than models with LEDs in the viewfinder metering display)
The Olympus OMs are great, and very charismatic, but inclined to be somewhat more tempermental and prone to malfunctions (in my limited experience).
Last edited by Galah; 02-14-2010 at 06:51 PM. Click to view previous post history.