Pentax KM

Pentax killed the screw mount in 1975 and needed bodies to sell the new bayonet on, so they shipped three at once: the K2, the KX, and the plain KM. The KM was the plain one. It took the old Spotmatic formula, the all-mechanical guts and the match-needle CdS meter, and bolted on the new K bayonet, which let you mount a lens with a quarter turn instead of threading it in like a lightbulb. That mount outlived almost everyone. A K-mount lens from 1975 still drops onto a digital Pentax today, and the KM is where the family tree forks.

In the hand it feels like what it is, a metal box from the seventies with no pretensions. The shutter runs from a full second to about 1/1000, mechanical the whole way, so it fires with or without a battery. Flash sync sits at 1/60, which is normal for a focal-plane shutter of the era and worth remembering when you put a strobe on it. The shutter sound is a clean mechanical clack, not loud, not soft, the kind of noise that tells you nothing went wrong. Film loading is the usual hinged back and take-up spool, no surprises.

The viewfinder is the reason people still reach for these. Pentax finders of this generation are bright and big, with a microprism collar around a central split-image patch, and focusing a fast fifty in dim light is genuinely easy. The meter is a needle on the right side of the frame. You twist aperture or shutter until the needle centers, and that is the whole interaction. It reads an average of the whole frame and is honest in even light. One thing to know going in: like the Spotmatic line before it, the KM was built around a 1.35V mercury cell (the PX625), and that chemistry has been banned for decades. So there is a mercury-cell headache here, which means an adapter or a voltage-correcting replacement to chase, or a one-stop error to correct if you just drop a modern 1.5V cell in.

What you do get is the ordinary lottery of a forty-year-old CdS meter. The cell itself can drift with age, the contacts corrode, the wiring inside gets tired, and plenty of KM bodies on the used market meter a little hot, a little cold, or not at all. When that happens, an incident or spot reading from the Zone Light Meter app gives you the exposure the body can no longer be trusted to find, and the all-manual dials take it without complaint. You meter the scene, set aperture and shutter by hand, and a dead or wandering needle stops mattering.

Who buys one. Students, mostly, and people who want a first film camera that will not break and will not nickel and dime them. It sits a notch below the K1000 in fame, which is funny, because the K1000 is essentially this camera from a year later with the self-timer and depth-of-field preview deleted. The KM has more features and usually costs less, because it never got famous. That is the case for it. The case against it is the same as for any forty-year-old SLR, you are gambling on dead seals and a tired meter. Buy one that has been serviced, or buy one cheap and meter it yourself.