KMZ MC Helios-44K-4 58mm f/2

Shoot the Helios-44K-4 wide open at a backlit hedge and the background starts to turn, a spiral of smeared leaves that tightens toward the corners of the frame while your subject sits still in the middle. That swirl is the reason most people go looking for a Helios at all, and this one draws it exactly as the M42 Helios-44M-4 does, because the glass is the same. KMZ changed the bayonet and the diaphragm drive and left the optics alone.

KMZ built the Helios-44K-4 from 1985 as the standard lens for its K-mount Zenit-Automat cameras. The six-element, four-group Biotar-derived formula got a new rear end and a 6-blade automatic diaphragm that the body stops down at the moment of exposure, so you focus and compose at f/2 whatever the aperture ring says. The first K-mount copies were single-coated; the MC multicoated version came after a 1987 KMZ order. Given the choice, take the MC. It holds contrast better against the light, though you still want a hood anywhere near the sun. At about 258 g it is noticeably heavier than the compact f/1.7 and f/2 Pentax primes it shares a mount with.

The factory's own figures are blunt. KMZ rated it at 42 lines/mm in the centre and 21 at the edge, so resolution halves once you leave the middle, and that weaker outer field is also where the swirl shows up. At f/2 the centre is usable, highlights glow and contrast is soft. By f/4 the glow has mostly gone, and by f/5.6 to f/8 it settles into a sharp, ordinary normal lens.

Portrait shooters get the most out of it. The 58mm focal length gives a little more working distance than a 50, and the swirl tends to show most clearly with the subject at head-and-shoulders distance and a bright, busy background a few metres behind. The catch is that the character lives almost entirely at f/2 and f/2.8. Stop down further and the six blades turn out-of-focus highlights into hexagons while the swirl fades. Keeping it wide open in daylight with ISO 400 film, on a body whose fastest speed is 1/1000, means an ND filter on the 52mm thread. Zone Light Meter applies the filter factor to the reading, so you can meter for f/2 and trust the number.

Fit is the other thing to know before buying. On a K1000 or any other Pentax K film body it mounts and works as intended. It has no electronic interface, though, so a modern Pentax digital body uses it correctly only in M mode, metering stopped down. Anyone planning to share it between film and digital should expect that extra step every time they change aperture.

Today it sits in the budget class, and it turns up less often than the M42 Helios copies that flooded the used market. The usual cross-shop is an SMC Pentax-M 50mm f/1.7, generally crisper wide open and with a lot less personality. People pick the Helios-44K-4 because it puts the swirl on a native bayonet, with no M42 adapter in the chain. Someone after a clinical normal lens will be happier with the Pentax.