Sigma 28-70mm F2.8 DG DN Review

Introduction

Ease of Use

Weighing in at just 470 grams and measuring nearly 10.35cm in length, the Sigma 28-70mm F2.8 DG DN Contemporary is a very light and compact lens given its versatile focal range.

It’s significantly lighter, by 44% in fact, and slightly shorter than its big brother, the outstanding Sigma 24-70mm F2.8 DG DN Art, which weighs in at 830 grams and measures nearly 12.5cm in length.

Compared to its main rival, the popular Tamron 28-75mm F2.8 Di III RXD, the new Sigma 28-70mm also has the edge, with the Tamron measuring almost 12cms in length and weighing in at 550g.

Note that the lens does extend by about an extra 2.5cm when fully zoomed out to 70mm. The direction of the zoom ring is the opposite to Sony lenses, which can be a little disconcerting when switching between them.

So if size and weight are key, the Sigma 28-70mm F2.8 DG DN Contemporary is the clear winner, albeit whilst offering 5mm shorter reach than the Tamron 28-75mm.

As seen in the photos below, it complements a 35mm full-frame camera like the new Sony Alpha A7 III that we tested it with, and it also feels very much at home on a smaller APS-C body, where the effective focal range changes to 42-105mm.

Build quality is excellent given the comparatively affordable price tag. The lens has a plastic shell with a mixture of metallic parts and a compound material, TSC (Thermally Stable Composite), used inside.

It also incorporates a brass bayonet mount that’s supposed to be more durable. The optical elements are made of high-grade glass.

In terms of features, the Sigma 28-70mm F2.8 DG DN Contemporary is a little sparsely attired, especially when compared to the Sigma 24-70mm F2.8 DG DN Art.

Neither lens includes built-in Vibration Reduction, instead relying on the camera body to supply this feature.

The new Sigma 28-70mm also loses both the Lock function switch and Auto Focus Lock (AFL) button that are found on the bigger, more expensive Sigma 24-70mm lens, in order to help achieve its small size and low weight.

Focusing is usefully internal and manual focusing is possible when set via the Focus switch on the lens barrel. Full-time manual focus override is also available at any time simply by rotating the focus ring.

Importantly, the lens is also fully compatible with the “Direct Manual Focus (DMF)” system feature of Sony cameras that enables the user to instantly switch between autofocus and manual focus.

The Sigma 28-70mm F2.8 DG DN Contemporary lens has a fairly generously sized focus ring, which is ridged for easier grip. There are no hard stops at the ends of the range, making it harder to set focus at infinity. Polariser users should be pleased that the more economical 67mm filter thread doesn’t rotate on focus.

When it comes to auto-focusing, the Sigma 28-70mm F2.8 DG DN Contemporary is a quick performer, taking about 0.15 seconds to lock onto the subject when mounted on the Sony Alpha A1 that we tested it with.

We didn’t experience very much “hunting” at all, either in good or bad light, with the lens accurately focusing almost all of the time. It’s also a very quiet performer, which makes this lens equally well-suited to both video recording and more candid stills shooting.

The Sigma 28-70mm F2.8 DG DN Contemporary ships with a plastic petal-shaped lens hood (LH706-01) that twists into place, but there’s no soft case included as with the more expensive Art version.

Focal Range

At the 28mm focal length the angle of view is 75.4 degrees.

28mm

At the 70mm focal length the angle of view is 34.3 degrees.

70mm

Chromatic Aberrations

Chromatic aberrations, typically seen as purple or blue fringes along contrasty edges, are not a problem for the Sigma 24-70mm f2.8 DG DN Art, even at the edges of the frame.

Light Fall-off

With the lens set to its maximum aperture of f/2.8, there is some obvious light fall-off in the corners at both ends of the zoom range. Stopping-down to f/5.6 virtually eliminates this.

28mm

70mm

Distortion

There’s some noticeable barrel distortion at the 28mm focal length and slight pincushioning at 70mm which is apparent in both the Raw files and uncorrected JPEGs.

28mm

70mm

Sunstars

The Sigma 28-70mm F2.8 DG DN Contemporary produces quite nice sunstars when stopped-down to f/16 and f/22, as shown below.

The lens is is a little susceptible to flare when shooting directly into the sun, even with the supplied lens hood fitted, but overall it is well controlled thanks to the lens’ Super Multi-Layer Coating.

Macro

The Sigma 28-70mm F2.8 DG DN Contemporary isn’t claimed to be a macro lens, but it delivers quite good performance nonetheless if you zoom to 70mm.

It has a minimum focusing distance of 19cm / 38cm at 28mm/70mm, and a maximum magnification ratio of 1:4.6 when set to the 70mm focal length. The following example demonstrates how close you can get to your subject.

Bokeh

Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc.

In the 28-70mm F2.8 DG DN Contemporary lens, Sigma employed an iris diaphragm with 9 rounded blades, which has resulted in quite nice bokeh in our view.

We do realise, however, that bokeh evaluation is subjective, so we’ve included several 100% crops for your perusal.

Sharpness

In order to show you how sharp the Sigma 28-70mm F2.8 DG DN lens is, we are providing 100% crops on the following pages.