The Sigma 28-70mm F2.8 DG DN Contemporary ($899) is a relatively compact zoom lens for full-frame cameras. It's smaller and less expensive than more common 24-70mm F2.8 optics, adding appeal for photographers working on a budget or with a desire to use a lighter kit. It costs a bit more, and has a little less zoom power, than the Tamron 28-75mm F2.8 Di III RXD. Ultimately, the Tamron remains our Editors' Choice winner for this type of lens, but it's a close call.

A Compact Zoom for E- and L-Mount

Sigma offers the 28-70mm F2.8 DG DN Contemporary in two versions. I tested the E-mount edition, compatible with Sony cameras, but you can also buy it in L-mount too. The L version is compatible with mirrorless cameras from Leica, Panasonic, and Sigma. Aside from the mount, the two versions are identical.

It's an especially appealing entry for L-mount owners. Tamron doesn't offer its lenses for the system, and it's the only slim zoom with F2.8 optics available. It competes with the heavier, pricier Sigma 24-70mm F2.8 DG DN Art ($1,100) and Panasonic Lumix 24-70mm F2.8 S Pro ($2,200), and is the clear value option.

The 28-70mm is a smaller and lighter all around than those 24-70mm lenses. It measures 4.0 by 2.8 inches (HD), weighs 16.6 ounces, and supports 67mm front filters. It does extend a bit when zooming, just like the Tamron 28-75mm, but is a little bit shorter and a few ounces lighter at its shortest position.

A lens hood is included, along with front and rear caps. The lens mount is sealed to protect your camera from dust and splashes, and the front element includes anti-smudge fluorine. You don't get the internal seals that are included with the Sigma 24-70mm F2.8 or Tamron 28-75mm, though—both are better choices if you wish to shoot in inclement weather.

The barrel is matte black polycarbonate. It includes an AF/MF toggle switch, a zoom ring, and a manual focus ring. The zoom control is positioned mid-barrel and is rubberized, with a ridged texture.

The manual focus ring is further forward, positioned at the front of the non-telescoping portion of the barrel. It's ridged too, but not rubberized. It turns with some pleasing resistance and a linear response—focus changes based on how far you turn the control, not how quickly you change it. It's one of the plus marks for video use, along with quick, quiet autofocus and a minimal breathing effect.

Close-up focus is another strong suit. It locks onto subjects as close as 7.5 inches at the wide angle and 15 inches when zoomed in, both figures measured from the image sensor. You can get within a few inches of subjects either way. Magnification is 1:3.3 life-size at the wide angle and 1:4.6 at the telephoto end when focused as close as possible.

Stabilization isn't included in the lens. If you use a full-frame Sony camera, you'll enjoy 5-axis IBIS with all but first-generation models, so you won't really miss it. Some L-mount cameras, notably the compact Sigma fp series, don't include IBIS.

In the Lab

I tested the 28-70mm Contemporary along with the 60MP Sony a7R IV. Resolution testing, performed in Imatest, shows good resolution wide open (3,700 lines) at 28mm, improving to very good at f/4 (4,000 lines).

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Edges are on the soft side at wider apertures, but sharpen significantly at f/5.6. Resolution is overall excellent here, and it falls just shy of outstanding at f/8 (4,800 lines). You'll continue to enjoy crisp results at f/11 and f/16, but it's a good idea to avoid using f/16 if you can manage—diffraction seriously hampers image quality at the smallest f/22 setting.

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Resolution tests at 50mm and 70mm net very similar results. There's a slight drop in scores at 70mm, but it still delivers good results wide open and excellent detail stopped down. This is a lens that's good enough to handle a 60MP sensor, and should perform just as well on 24MP and 45MP cameras.

There's some distortion visible in Raw images, but it's automatically removed if you use your camera's JPG mode. Without them, we see some barrel distortion at 28mm and the pincushion effect at 50mm and 70mm. Adobe Lightroom, our standard processing software for camera reviews, includes a profile for one-click correction. The profile also removes a vignette from Raw images. Without it, you'll note dimmed corners at f/2.8.

Background blur draws many photographers to F2.8 zooms. The Sigma 28-70mm does a fine job netting the look, either by focusing close at wider angles or keeping the aperture opened when zoomed in.

Defocused highlights retain a generally circular shape toward the edges of the frame at f/2.8, a plus for close-up bokeh shots where you'll want to keep the aperture wide open. There's a slight cat's eye at 70mm, most noticeable toward the edges and corners. The rounded aperture blades do their work at f/4, though, drawing circular highlights, even toward the frame edges.

For Small Cameras and Packing Light

The Sigma 28-70mm F2.8 DG DN Contemporary is an especially appealing lens for photographers who carry a full-frame camera and value a compact kit over the wider coverage offered by 24-70mm zooms.

The lens pairs well with slimmer models like the Panasonic S5 and Sony a7C, and still offers good balance on a larger camera like the Panasonic S1R or the Sony a7R IV that I used with it.

It's easy to recommend to L-mount customers, where Sigma faces no direct competition. The Panasonic Lumix 20-60mm zoom is an intriguing alternative if you want something that's lighter and covers a wider angle, but its F3.5-5.6 aperture isn't as well suited for working in dim light or for blurring backgrounds.

If you use a Sony camera, the Tamron 28-75mm F2.8 is a little more lens for a little less money, and we like it just a bit more overall. Its internal sealing makes it a better fit for outdoor photographers, and the slightly longer focal length comes in handy for portraits.