Leica APO-Summicron-M 75mm f/2 ASPH

A head-and-shoulders portrait at f/2, close range, available light, with the catchlight in the eye rendered crisp enough to count eyelashes and the ear already melting into nothing. That is the frame this lens owns and most fast portrait glass loses. Wide open, the 75 APO is already at its best, no color fringe on the bright edge of a cheekbone, no glow softening the iris, just a hard plane of focus sitting in a quiet wash of out-of-focus background. You do not stop down to fix it. There is nothing to fix.

The apochromatic correction is the whole point. Leica built this thing to put red, green, and blue focus on the same plane, which is why high-contrast edges (a white collar, backlit hair, a specular highlight on glasses) come back clean instead of haloed in magenta and green. Most fast lenses make you choose between sharpness and smooth bokeh; the floating element here lets you keep the sharpness at close distance without the bokeh going nervous behind it. Contrast is high but not brutal, and the falloff from sharp to soft is gradual rather than the abrupt edge you get from a Sonnar.

Who reaches for it: portrait and editorial shooters working on the M who want a tighter framing than the 50 and a more flattering working distance, plus documentary people who like 75mm for picking a face out of a crowd. It is not a street lens in the snapshot sense. The frame lines are small in the finder and the depth of field at f/2 is a sliver.

That sliver is the honest weakness, and it is a focusing problem, not an optical one. The M rangefinder base is short for a 75mm at f/2, so nailing a near-eye wide open takes practice and a well-calibrated body. Miss by a hair and the lens punishes you with all that resolution, showing the focus landed on an eyebrow. People who shoot it at distance rarely complain; people who shoot it at minimum focus learn to bracket their focus by rocking slightly.

It sits at the top of the price class, several thousand dollars, and the cross-shop is usually the older 75mm Summilux f/1.4 (dreamier, softer wide open, cheaper used) or the Voigtlander 75mm f/1.5 Nokton (a lot of lens for a fraction of the money, with more character and less correction). You buy the APO when you specifically want the clinical wide-open result and will pay for it. Some shooters find it too perfect and miss the texture of older glass. That is a taste call, not a flaw.

One metering note. Because this lens earns its keep at f/2 in low light, meter for the wide-open shot you actually intend to take rather than a stopped-down default. In Zone Light Meter, lock your reading at f/2 and let it drive the shutter so your exposure matches the thin-DOF frame you are composing, not a brighter aperture you will never use here. The 49mm thread takes a standard ND if you need to hold f/2 in daylight.