Leica Elmarit-M 21mm f/2.8 ASPH

Leica built this one to fix a problem of their own making. The pre-aspheric 21mm Elmarit-M from the 1980s (the 11134, 8 elements in 6 groups) was a respected lens, but it went soft in the corners wide open and showed some vignetting there, and by the mid-1990s the M system wanted an ultra-wide that held up across the frame at full aperture. The ASPH version arrived in 1997 with one aspherical surface and a reworked optical block, nine elements in seven groups. It had a long production run, and in 2011 the f/3.4 Super-Elmar-M 21mm ASPH joined the lineup alongside it.

Wide open at f/2.8 it is already sharp across most of the frame, which was not a given for a 21mm rangefinder lens of that era. Stop it to f/5.6 or f/8 and the corners snap into line, distortion stays low enough that you can shoot a building facade without panicking in post, and contrast is the high-microcontrast Leica look that separates fine detail without crushing it. Color is neutral and slightly cool. Flare is well controlled for an ultra-wide with a large front element, though shoot it straight into a streetlight at night and you will see the veiling glare every fast wide produces.

Nobody buys a 21mm for bokeh, and this lens is no exception. Depth of field at this focal length is enormous, so there is very little background blur to talk about. What you get instead is the ultra-wide signature: near objects come on strong, the deep planes stack up, and you feel planted inside the scene rather than standing back from it. Use it for landscape and architecture, for documentary work in tight interiors, for street if you like working close and want the whole room in the frame. Get near your subject or the composition goes flat.

The honest limitation is the same one every M-mount ultra-wide carries: you cannot see the framelines. The M finder does not cover 21mm, so you shoot with an external optical finder in the accessory shoe, which slows you down and means you are composing in one window and focusing in another. It is a real adjustment, and not everyone keeps an M body around for wide work because of it. The 55mm filter thread is generous and takes standard screw-in ND and polarizers, useful for long landscape exposures.

On the used market this sits in serious-money territory, cross-shopped against the f/3.4 Super-Elmar-M and the older f/2.8 pre-ASPH for people who want the rendering on a budget. The f/2.8 maximum aperture is its edge over the slower Super-Elmar, though in practice you stop down for most ultra-wide work anyway. One metering note: at f/2.8 in a dim interior you can meter and frame wide open, and because depth of field is already deep you rarely need to stop down for focus, so set Zone Light Meter to your taking aperture and trust it.