Pentax SMC Takumar 55mm f/1.8

Point it straight into a low winter sun, the kind of frame that turns most 1960s glass into a milky gray smear, and the SMC Takumar holds contrast. Pentax's Super Multi Coating, seven layers of it, was a real advance when this version arrived in 1971, and it shows exactly where single-coated rivals of the M42 era fall apart. Backlight, a bright window behind a subject, a row of streetlights at night: veiling flare that would gray out a contemporary 50mm gets suppressed, and you keep a usable black.

The optics are a modified double-Gauss, six elements in five groups, a fast-standard layout with one cemented doublet split into two air-spaced elements rather than the textbook six-in-four arrangement, and it behaves the way a good double-Gauss should. Wide open at f/1.8 the center is sharp under a soft halo of spherical aberration that fills in by f/2.8 and snaps to genuinely crisp by f/5.6. Out-of-focus rendering is calm and rounded, no nervous edges, no swirl. Color skews slightly warm and saturated, which flatters skin and autumn foliage and is part of why people still hunt these down for portraits on digital bodies with a cheap adapter.

In its earlier Super-Takumar form this 55mm was the standard prime on the original Spotmatic, the lens a generation of photographers learned the craft on; the multicoated version carried that workhorse role forward through the Spotmatic II era. It is a documentary and everyday-fifty tool before it is anything specialized. The 55mm focal length sits a hair longer than the usual 50, which on full frame buys portraits a touch more working distance and a slightly flatter perspective on faces. Stopped down it makes a perfectly competent landscape lens, though f/16 is as far as it closes, so deep-focus near-far compositions need some planning.

The honest weakness depends on which copy you grab. Buyers cross-shop the SMC 55mm f/1.8 against its own faster sibling, the 50mm f/1.4, and against the earlier Super-Takumar versions. Some of those early Takumars used thoriated glass that is mildly radioactive and yellows with age. Reports differ on whether the multicoated 55mm uses any thoriated element at all; if your copy shows a yellow cast viewed through the glass, a long UV bath clears most of it. Either way it is the better-coated pick for backlight. Still, inspect any used lens for haze and oily aperture blades before you pay.

For metering, this is a wide-open available-light lens first. At f/1.8 you can read a dim interior off the brightest thing in the frame and place it where you want it on the scale, then stop down for the actual exposure. Treat that f/1.8 reading as your low-light anchor. If you screw a deep ND or a stack of filters onto the 49mm thread for long daylight exposures, dial the filter factor into Zone Light Meter so the suggested shutter speed already accounts for the light you are throwing away. Decades on, it stays one of the great value fast primes, and it is still genuinely good in the one situation that used to break every lens in its class.