Canon EF 100mm f/2.8 Macro USM

Most people shopping this lens are really deciding whether to spend the extra money on the 100mm f/2.8L IS Macro that arrived in 2009. The honest answer is that the optics are nearly a wash. The L adds Canon's Hybrid IS, which corrects the angular and shifting movement that wrecks handheld close-up work, plus weather sealing and a red ring. What it does not add is meaningfully better resolution. This non-L USM version, the one in production from 2000 through the middle of the next decade, tests as sharp as lenses costing several times more, and at macro distances on a tripod the stabilizer does nothing for you anyway.

It focuses to 1:1 life size on its own, no extension tube required, with an internal focusing design that keeps the front element from rotating or extending. Twelve elements, ring USM, fast and quiet. Wide open at f/2.8 it is already biting sharp in the center, which is unusual for a macro lens and the reason so many people press it into double duty as a short portrait lens. Stop down to f/4 or f/5.6 and the corners catch up. The bokeh is smooth and neutral rather than characterful, clean and round wide open and taking on a slight octagonal shape from the eight-blade diaphragm as you stop down. Do not expect swirl or drama. This is a clinical rendering lens, and that is the point.

The flat-field correction is what separates it from a portrait prime pretending to do macro. Photograph a stamp or a circuit board and the plane stays sharp corner to corner with no field curvature pulling the edges out of focus. Color is accurate and contrast is high without being harsh. Flare is well controlled, though shooting into a bright source will lift the shadows a touch, so use the hood.

The honest weakness is the focus hunting. The full-time manual override is there, but at 1:1 the autofocus will rack the entire range looking for a target, and the focus limiter switch only helps so much. Most macro shooters give up and focus manually by rocking the camera back and forth. The other thing is depth of field, which at life size is paper thin even at f/16, but that is physics, not a flaw in the glass.

This is where the bellows factor matters. As you focus closer the effective aperture drops, and at 1:1 you lose two full stops of light. Zone Light Meter computes that extension compensation for you, so a reading that says f/8 actually wants the exposure of f/16 once the lens is racked all the way out. Hand metering a macro scene without accounting for it leaves you two stops underexposed every time.

It sits today as the smart-money choice. The L is barely sharper on paper, and not in any way you'll see in a print. It costs more and earns its keep only if you shoot handheld macro or work in the rain. For studio product work, copy work, flowers, and the occasional headshot on a tripod, the plain USM does everything the red ring does for less.