Sigma 28-45mm f/1.8 DG DN Art review

Long gone are the days of Sigma’s reputation as simply a manufacturer of cut-price versions of camera-brand optics.

These days, Sigma wants to be known as a true innovator, designing lenses which push the boundaries of what’s possible – and the brand-new 28-45mm f/1.8 DG DN Art lens is the first example of that.

It breaks new ground as the world’s first zoom lens for full-frame mirrorless cameras with a constant f/1.8 aperture.

Sigma used to make an 18-35mm f/1.8 zoom for crop-sensor DSLRs, which offers roughly the same focal length but is not as advanced in terms of AF or image quality.

This lens provides optical quality and light-gathering capabilities that can rival prime lenses. Key features include an internal zoom design, fast and quiet AF motors and a separate aperture ring that can be de-clicked or locked.

Add minimal focus breathing, two AFL buttons, plus a focus mode switch on the body, and it’s evident this is a lens aimed at both still and video shooters.

Focal length range

Obviously, you don’t get something for nothing – and in this case it’s the rather limited zoom range that goes from 28mm wide angle to 45mm, just short of what many feel is the ‘standard’ 50mm focal length. In use, this does quickly become a limiting factor.

You always seem to want just that bit of extra space at the wide end or that tiny bit more at the long end.

While it could potentially go wider or longer, this would mean a smaller maximum aperture – and there are plenty of lenses offering exactly this.

Alternatively, making a 24-70mm f/1.8 lens would push the laws of physics and be much bigger, heavier and more expensive.

At £1299, for its 960g weight and large 82mm front filter size, it’s already a chunk to fork out for and a ballast to carry around.

What this can do is replace 28mm, 35mm and 45mm f/1.8 primes in a single lens, and offer more precise framing for focal lengths in between. Not even Sony provides these focal lengths as f/1.8 versions. The closest matches from Sony are a 28mm f/2, 35mm f/1.8, 40mm f/2.5 or 50mm f/1.8.

By going with the Sigma, you’d spend roughly the same as buying three primes but get a lens with a consistent maximum aperture and much more advanced features – from faster AF to weather sealing and, of course, the ability to zoom.

Focusing

The lens enjoys extremely fast and precise AF capabilities from the high-response linear actuator AF. It snaps into focus quickly and feels every bit as accurate as Sony’s latest AF lenses.

An unusual feature is the minimum focusing distance of 30.2cm, which is the same at all focal lengths. That’s respectable for a zoom, but not as close as a dedicated prime.

Image quality

What is as good as a prime is image quality at pretty much all focal lengths, which is impressive. The lens is sharp across the frame, but when shot wide open there is a little bit of softening in the corners. Nevertheless, the lens resolves high detail and is still very sharp.

The colours are natural and, like most Sigma zooms, control of flare is excellent – helped by the included lens hood. There is barely any ghosting and the contrast is high. Even shooting directly into the sun, it was difficult to provoke any nasty flare artefacts.

Bokeh is also great thanks to the 11-bladed aperture. Some cat’s-eye issues are present at the longer focal length, but it’s not too unpleasant. In fact, the lens can give a swirly-style, vintage-look bokeh in certain shots.

Chromatic aberration can occur at wider settings, but it’s minimal and nothing to worry about.

When we tested the lens, there was no lens correction data for our editing software. As a result, there was some pincushion distortion at 45mm and barrelling at 28mm, as well as slight vignetting in the corners.

Once lens correction profiles are available and fully updated, these issues are easily resolved. Meanwhile, we tried the Sigma 24-70mm f/2.8 profiles, which worked well.

Build

The build quality is fantastic, the lens is resistant to weather and has coatings to repel oil and water. Similar to the 24-70mm, it includes almost every feature – though lacks image stabilisation.