Sigma 28-70mm F2.8 DG DN Contemporary Review

While Sigma’s Art line lenses are its top-flight optics that deliver the best image quality it can, the Contemporary lenses are designed to offer high performance yet have a more compact and lightweight form. They are also more affordable than the Art series optics.

Nevertheless, Sigma based the 28-70mm F2.8 DG DN Contemporary, also known as the Sigma 28-70mm F2.8 DG DN C, on the excellent 24-70mm F2.8 DG DN Art with the aim of producing a smaller standard zoom lens with a constant maximum aperture of f/2.8. In fact, it’s the smallest and lightest full-frame standard zoom lens with that aperture.

Naturally, reducing the zoom range from 24-70mm to 28-70mm has an impact on the size and weight of the lens, but Sigma’s downsizing is impressive. The end result is a lens that’s suitable for a wide range of photography and that won’t weigh you down.

Inside the Sigma 24-70mm f/2.8 DG DN A there are 19 elements arranged in 15 groups, but the Sigma 28-70mm f/2.8 DG DN C is constructed from 16 elements in 12 groups. Those 16 elements include three aspherical elements, two SLD (special low dispersion) elements and two FLD (‘F low dispersion) elements.

The aspherical elements help to maintain sharpness across the frame while the SLD and FLD elements reduce chromatic aberrations. The two FLD elements are made from glass with an optical performance similar to that of fluorite at a fraction of the cost and weight – making it a good choice for a Contemporary line lens.

There are also elements with Sigma’s Super Multi-Layer Coating and Nano Porous Coating which are designed to boost contrast and reduce flare when the subject is backlit.

As often seems to be the case, the 28-70mm f/2.8 DG DN C’s aperture is formed by 9 rounded blades.

Sigma has also made the Sigma 28-70mm f/2.8 DG DN C dust and splash-proof and if you run your finger around the outer edge of the mount, you can feel a rubber ring that forms part of its sealing. According to Sigma, the weatherproofing is said to have a simpler structure than in the 24-70mm f/2.8 DG DN A, but there’s no information about whether that’s a good or bad thing.

Further good news for outdoor photography is that the lens’s front element has a water and oil-repellent coating so that raindrops bead off and fingerprints aren’t too problematic.

The focusing unit has a single lightweight element within it and it’s driven by a stepping motor. Keeping the weight of the focusing unit down helps to increase its speed of movement while reducing the sound that it makes in operation.

At the 28mm end of the zoom, the closest focusing distance is 19cm, which means the working distance is 6.9cm. In practice, this seems very close and while it doesn’t enable true macro shooting, the reproduction ratio is 1:3.3, a third of life-size.

However, at the 70mm end, the closest focusing distance extends to 38cm and the maximum reproduction ratio is 1:4.6.

While the 24-70mm f/2.8 DG DN A weighs 830g with the Sony E-mount, the L-mount version weighs 835g. However, the Sigma 28-70mm F2.8 DG DN, weighs just 470g in either mount, making it 360g or 365g lighter.  Of course,  some of that weight saving is down to the reduction in the focal length range, but the optical construction also plays a part.

The 28-70mm F2.8 DG DN is also 101.5mm in length and 72.7mm in diameter, while the 24-70mm lens is 124.9mm (E-mount) or 122.9mm (L-mount) in length and 87.8mm in diameter. That makes the 28-70mm optic at least 21.4mm shorter and 15.1mm narrower. Those numbers may not sound that significant, but they make an appreciable difference when you’re sliding the lens into a bag and it’s a very nice match on a small mirrorless camera like the Sony A7 III or A7R IV.

Sigma 28-70mm f2.8 DG DN C vs Canon RF 28-70mm F2L USM

Sometimes a reduction in weight can also see a reduction in the build quality, but the 28-70mm F2.8 DG DN C feels very well made and is nicely finished. It also has a metal mount, which should mean it will last.

Sigma has adopted a traditional approach for the 28-70mm F2.8 DG DN Contemporary and the only switch on its barrel is to flick between manual and automatic focusing. It also only has two rings, one for focusing manually and the other for zooming between focal lengths.

The focusing ring is farthest from the lens mount, towards the front element, but it’s still within easy reach of your left forefinger and thumb. It has a smooth, easy action that just takes a little pressure from your finger to rotate but doesn’t feel loose.

Helpfully, the focusing is internal which means that the front element of the lens doesn’t rotate during focusing – either using the AF system or focusing manually. That’s good news if you’re using a polarising or neutral density filter.

The focusing mechanism is set by the MF/AF switch at the 3 o’clock position on the lens barrel. This snaps smartly in one direction or the other. When it’s in the MF position, provided ‘MF Assist’ is activated in the Sony A7R IV”s menu, the area under the AF point enlarges to make it easier to see small details. A distance scale also appears towards the bottom of the viewfinder or the camera’s rear screen, which helps guide the direction of the focus adjustment, which as it’s ‘by wire’ has no physical endpoints.

The zoom ring is broader than the focusing ring and sits closer to the camera. It’s at the point that my left hand goes to automatically when I’m supporting the camera with two hands. This ring is a bit stiffer than the focusing ring and requires pressure from my thumb and finger, but it still rotates smoothly.

There’s no lock on the zoom ring,  but it didn’t creep from the shortest point as I carried the camera and lens on a strap across my body.  I even tried shaking the camera, but the zoom didn’t shift its position.

I tested the Sony E mount version of the Sigma 28-70mm F2.8 DG DN Contemporary on the 50Mp Sony A1 and 61Mp Sony A7R IV, and it’s clear it can resolve and high level of detail. It’s sharpest at the widest end of the zoom range and when stopped down to f/5.6, but it’s still good at f/2.8.

If you’re pixel-peeping you’ll spot that the 70mm end is a little softer than the wider end and the impact of diffraction at f/22 is more apparent. At 70mm, it’s best to use the 28-70mm F2.8 DG DN C at between f/4 and f/16, but I’d happily shoot wide-open to isolate a subject from the background.

Naturally, the sharpness level falls off towards the corners of the image, but it’s not excessive. Again, it’s more noticeable at 70mm than at 28mm, at which it’s pretty subtle. Closing down to f/4 improves the corner sharpness.

Sigma has created in-camera and post-capture correction profiles for the 28-70mm F2.8 DG DN C. If the profile isn’t turned on in-camera, corner shading is apparent at every focal length when the aperture is wide open. Closing down to f/4 improves the vignetting markedly and reducing the aperture to f/5.6 almost eliminates it completely.

Alternatively, activating the in-camera and post-capture correction profiles avoids the vignetting issue altogether. If I were to be pedantic, I’d mention that at the widest apertures the corners look a tiny fraction too bright, but not so much that you’re likely to notice it in normal photography.

The correction profiles also do a very good job of correcting the curvilinear distortion from the lens. Without them, if you photograph a subject with lots of straight lines at the 28mm end, there’s clear barrel distortion. Zooming to 35mm makes the barrel distortion much less obvious and at 50mm and 70mm, there’s similarly subtle pincushion distortion. With the correction profile turned on in-camera or applied post-capture in Adobe Camera Raw or Lightroom, any straight lines look just as they should.

I spotted the occasional hint of chromatic aberration along a few high contrast edges when the correction profiles were turned off, but they disappear when the profiles are turned on.

As well as enabling fast shutter speeds to be used in low light, a key reason for opting for an f/2.8 lens is to enable background blur. At f/2.8, the 28-70mm F2.8 DG DN C renders out of focus areas naturally soft and small highlights are rounded rather than nonagonal.

Sigma’s decision to use a single AF element and a stepper motor ensure that the 28-70mm F2.8 DG DN C focuses quickly and quietly. It’s not quite silent, but it’s very close and it’s unlikely that a camera-mounted microphone will pick up any focusing sound in most outdoor environments.

In addition, focus breathing is controlled very well and the framing remains constant as the focus distance changes.

The lens is also compatible with Sony’s Eye AF system, which in the A1 can be set to detect humans, animals or birds.

Follow the link to browse and download full-resolution images shot using the Sigma 28-70mm F2.8 DG DN Contemporary.

Sigma 28-70mm F2.8 DG DN Contemporary image gallery

While lenses like the Sigma 24-70mm F2.8 DG DN Art and Sony FE 24-70mm F2.8 GM deliver first-rate image quality in a wide range of situations, they are fairly bulky and heavy. The Sigma 28-70mm F2.8 DG DN makes a great alternative that doesn’t compromise on image quality dramatically.

It’s best at the widest end, and if you use the 70mm it’s worth sticking to f/16 or wider apertures, but it doesn’t really disappoint at any focal length or aperture.

The Sigma 28-70mm F2.8 DG DN is also well made and weather-sealed, which makes it an attractive choice for long days out. I always tend to veer towards wide-angle lenses, so I missed the extra 4mm offered by a 24-70mm f/2.8 lens, but I’d happily accept the weight-saving.