KMZ MC Zenitar-M2s 50mm f/2

Pentax moved to its K bayonet in 1975. Twenty years on, KMZ was still putting out normals for the M42 screw mount, and the MC Zenitar-M2s 50mm f/2 arrived in 1995 for the many Zenit owners who still screwed their lenses on. Underneath, it is the K-mount Zenitar-K2 in a different mount: six elements in four groups, computed by Byshkin. The M2, the K2 and this M2s were simplified, cheaper constructions of the original MC Zenitar 2/50, so the savings went into how the lens was put together. The trailing s comes from the surnames of V.V. Strakhov and A.P. Sorokin.

At the camera, the diaphragm is what you notice first. Unlike the preset Helios-44-2 or the plain-iris Industar-50-2, the M2s has a six-blade automatic diaphragm worked by the M42 pin. On a body that presses the pin at release, you compose and focus with the finder bright at f/2, and the blades only close to the set stop as the shutter fires. On mirrorless, buy an adapter with a pin-pressing plate inside. A plain ring adapter that never touches the pin can leave the blades wide open whatever number the ring shows, which is a confusing way to lose an afternoon of depth of field.

How it draws is harder to pin down from paper, because the published record for the M2s is mostly specifications. In many owners' sample galleries it looks fairly clean at f/2, and frames made at f/5.6 or f/8 look crisp across ordinary print sizes. Take that as an impression, not a lab result. The MC in the name means multicoating, which should resist flare better than older single-coated Soviet glass. Fit a hood anyway when the sun is near the edge of the frame.

Its limits are easy to state. It is not the fast Zenitar: the Zenitar-M f/1.7 gives roughly half a stop more for dim interiors, and plenty of buyers would take that over the f/2. Close focus is 0.35 m, which works out to roughly a 1:5 reproduction ratio. Good for a place setting or a hand holding a cup; no use for insects. And because this was a cost-reduced build of an existing lens, judge each copy on its own. Check the focus feel, watch the pin spring back, and look for oil on the blades before you pay.

Prices sit in budget territory, and the usual cross-shop is a Helios-44M for character or a Takumar 55mm f/1.8 for a more expensive build. At about 190 g the M2s is light enough to leave on a body all day, and on a walk through town that matters more than the half stop you gave up.

The 46mm filter thread is the practical detail. Shooting wide open in sunlight is where it bites: with ISO 100 film, f/2 in full sun wants something close to 1/8000, while a Zenit-E tops out at 1/500. That gap is four stops, so a 46mm ND16 (or a step-up ring to a size you already own) is the realistic answer for daylight portraits at f/2. Enter the 16x factor in Zone Light Meter and the reading you carry back to the camera already includes it.