Leica Super-ELMAR-M 21mm F/3.4 ASPH.

This Leica M wide-angle prime suits full-frame rangefinder photography where a small, light lens matters. The 21mm focal length frames broad scenes, so it fits architecture, landscapes, interiors, street and travel work. That breadth rewards working close to the subject and using foreground interest. Leica introduced the design in 2011 and still builds it today.

The trade-off is a modest f/3.4 maximum aperture, which limits handheld work in dim interiors. Focusing is manual only, matching the deliberate pace of rangefinder shooting. There is also no stabilisation or weather sealing, so daylight and fair conditions suit it best. Size and weight remain its clearest strengths.

At 9.3 oz (263 g), this lens adds little weight to an M body. It measures 1.69 in (43 mm) long and 2.6 in (66 mm) across, so it stays compact on the camera. The front takes standard 46mm screw-in filters, a common size that is easy to find.

The 21mm focal length is the heart of this lens. It frames wide views of buildings, landscapes and tight interiors without stepping back. That breadth rewards working near the subject and building foreground interest into the composition. Streets and markets also fit, since the lens takes in a whole scene from a normal standing distance.

Depth of field runs deep at this focal length, even at f/3.4. Keeping an entire scene sharp is straightforward, and zone focusing at a set distance works well for quick handheld shots.

The f/3.4 maximum aperture is modest. It covers daylight and well-lit interiors comfortably. Dim evening scenes will need higher ISO settings or a steady support. Filling the frame still needs an active approach, since distant subjects look small at 21mm.

Closest focusing sits at 2.3 ft (70 cm). That is close enough to include foreground detail, such as a doorway or paving pattern, inside a wide frame. The framing stays scene-led at this distance, which matches the lens's purpose.

The front element carries a fluorine coating. Fluorine helps water and oil bead up and slide off, so the surface wipes clean easily. That helps on dusty streets or coastal shoots where fingerprints and spray build up. It suits travel days when a quick wipe beats a careful clean.

There is no weather sealing, so the lens needs care in rain, dust and spray. Stabilisation is also absent. At 21mm, handheld shutter speeds can be fairly slow before blur shows, so this gap matters less than it would on a long lens. The features specification score is 19 out of 100.

The optical path uses eight elements in seven groups. It includes aspherical and bi-aspherical elements, whose specially shaped surfaces help reduce distortion and spherical aberration. Distortion can bend straight lines in wide-angle designs, so that correction serves the architecture this lens often frames.

Four elements in the design help reduce chromatic aberration, the colour fringing that can appear along high-contrast edges. That suits detail-rich subjects such as cityscapes.