KMZ Helios-44-2 58mm f/2

Two aperture rings sit on a Helios-44-2, and the whole lens makes sense once you know why. One of them clicks. It sets nothing by itself; it only marks where the diaphragm will stop. The other turns freely with no detents at all, and that one actually closes the eight blades. You focus at f/2 on a bright finder, then roll the working ring until it bumps against the preset value. There is no pin for the camera to press, so on a Zenit-E or a Zenit-TTL you meter at working aperture after closing the ring.

The "-2" marks the mount. When the Zenit-E switched to the M42 screw, this became the first Helios-44 cut with the M42 x 1 thread and the 45.5mm flange, which is also why it fits nearly any mirrorless body today through a cheap adapter. Production ran from 1966 to 1999. It came as the kit lens on the Zenit-E, Zenit-B, Zenit-ET and Zenit-10, and KMZ was only one of its makers: the Valdai "Jupiter" branch plant built it too, as did MMZ in Belarus, later BelOMO. So the copies on a flea-market table rarely match. Barrels, engraving and coatings shift with the factory and the decade.

Optically it is a 58mm double Gauss descended from the Zeiss Biotar, six elements in four groups. Wide open there is enough field curvature and off-axis astigmatism to stretch out-of-focus highlights into arcs toward the corners, so a hedge or a stand of birch behind someone a few metres away twists around the frame. Most modern fifties are corrected hard enough that they never do this. The centre holds reasonable detail at f/2, contrast is low, bright edges glow faintly, and the corners fall away. By f/4 the haze lifts. From f/5.6 to f/8 it is properly sharp across most of the frame.

Flare is the real problem. With a single coating and the sun anywhere near the frame, the image veils over and contrast collapses, so a 49mm hood should live on it permanently. The preset diaphragm pays you back elsewhere. Against the later 44M, which added a pin-driven automatic diaphragm, the 44-2 is slower to work on a film body, yet on adapted mirrorless cameras that stepless working ring gives video shooters smooth, silent aperture pulls. Eight blades also keep stopped-down highlights closer to round than the six-blade 44M manages.

Metering with a handheld meter has one trap. Take the reading in Zone Light Meter, set the f-number it gives on the preset ring, focus wide open, then close the working ring before you fire. Forget that last twist and the frame goes through at f/2 with a shutter speed chosen for f/8, four stops over. Nothing warns you, either: the finder simply stays bright.

Prices sit firmly in budget territory. People cross-shop it against the Super-Takumar 55mm f/1.8, usually a touch crisper wide open, with a calm, flat background and far less of the twist. Buy the 44-2 for the look and the two-ring preset, accept a close focus that stops at 0.5 m, and expect about 230 g in the hand. Check that the helicoid turns smoothly and the preset ring clicks cleanly before you pay, and expect a slightly different lens depending on which factory stamped the barrel.