Sigma 17mm F/4 DG DN | C

The Sigma 17mm F/4 DG DN | C is an ultra-wide prime for full-frame mirrorless cameras. It comes in Leica L and Sony E mounts, so choose the version made for your camera. Sigma introduced it in 2023, and it remains in production today.

At 17mm, the lens suits wide landscapes, tight interiors and architecture, where you want the whole scene in frame. The fixed f/4 maximum aperture is the main trade-off. It keeps the design small, while gathering less light in dim conditions. It suits anyone who prefers carrying one small wide prime over a zoom.

The lens measures 2.52 in (64 mm) across and 1.92 in (48.8 mm) long, so it stays short and slim on the camera. The Leica L version weighs 7.9 oz (225 g). A screw-in filter must match the 55mm front thread. The physical specification scores 93 out of 100.

17mm is an ultra-wide focal length on full frame. It lets you frame whole rooms, tall buildings and open landscapes from close range. Whatever stands near the camera becomes prominent, so foreground placement is a big part of the composition.

At 17mm, depth of field stays deep even at f/4. That helps keep both a near foreground and the distant horizon sharp in a landscape. It also means strong background blur is hard to achieve, so this lens is about the whole scene rather than an isolated subject.

The f/4 maximum aperture suits daylight work. In dim interiors you will need a higher ISO or a slower shutter speed. Ultra-wide perspective also exaggerates converging lines when you tilt the camera, so keeping it level helps keep building edges straight.

The lens focuses as close as 0.4 ft (12 cm). You can set it a few inches from a foreground detail such as a rock or a doorway edge. Focused that close, a near detail appears large, while the background blurs. The optics specification scores 67 out of 100.

The lens is weather sealed, which helps protect it against dust and moisture during outdoor shooting. Landscape and architecture work often happens out in the weather, so this fits the likely use.

There is no built-in image stabilization. Any shake reduction must come from the camera body, if your camera offers it. Camera shake is less visible at 17mm than with longer focal lengths, which partly offsets the gap. The features specification scores 32 out of 100.

The front element also lacks a fluorine coating, the water- and oil-repellent finish some lenses carry. Cleaning smudges and spray off the glass takes a little more care.

The design includes aspherical elements, whose shaped surfaces help correct optical faults such as distortion. Interiors and buildings are full of straight edges, where distortion would show. Low-dispersion glass helps reduce chromatic aberration, where colors focus differently and leave fringes along high-contrast edges. Internal focusing moves inner groups, so the lens does not extend while focusing.