Introduction

Ease of Use

Weighing in at 1140g and measuring 19.92cm in length, the Sigma 100-400mm F5-6.3 DG DN OS is actually quite lightweight and compact given the focal range that it covers.

As seen in the photos below, it's at home on a small full-frame camera like the Sony A7 III, at least until you zoom to 400mm. This is a lens that you can comfortably hand-hold for long periods of time. Note that the lens extends by quite a long way when zoomed out from 100mm to 400mm.

Build quality is very good. The Sigma 100-400mm F5-6.3 DG DN OS lens has a plastic shell with a mixture of metallic and plastic parts used inside.

The optical elements are made of high-grade glass with 4 SLD glass elements to reduce color fringing and chromatic aberrations, while the lens commendably has a dust and splash-proof construction and a brass mount.

In terms of features, the Sigma 100-400mm F5-6.3 DG DN OS offers everything that you need from a telephoto zoom lens.

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 when set on the camera body.

The focus limiter switch has three settings, FULL, 6m-infinity and 1.12/1.6-6m, which helps speed up the auto-focusing if you know how far your subject is from the lens. You can also use the USB dock to customise these ranges to your own needs. There's no distance scale on this version of the lens.

There is a dedicated Auto Focus Lock (AFL) button that can also be re-configured to assign various functions to the lens barrel.

The built-in Vibration Reduction is activated via the OS switch on the lens barrel, which offers around 4 stops of compensation. The OS system has two modes - mode 1 is suitable for general photography, and mode 2 is best for panning shots of moving subjects in a horizontal direction (not vertical). You can also turn it Off if you wish.

The Sigma 100-400mm F5-6.3 DG DN OS lens features a zoom lock switch that can be locked at the 100mm focal length, which is useful when storing the lens.

The Sigma 100-400mm F5-6.3 DG DN OS lens has a large focus ring, and it is ridged for easier grip too. There are hard stops at both ends of the range, making it easier to set focus at infinity. Polariser users should be pleased that the 67mm filter thread doesn't rotate on focus.

When it comes to auto-focusing, the Sigma 100-400mm F5-6.3 DG DN OS zoom is a fairly slow performer, taking about 0.25 seconds to lock onto the subject when mounted on the Sony A7S III that we tested it with.

We also experienced some "hunting", too, both in good or bad light, although the lens did eventually lock on to the subject. On a more postive note, it is a very quiet performer, thanks to the built-in HSM (Hyper Sonic Motor), which makes this lens well-suited to video recording.

The Sigma 100-400mm F5-6.3 DG DN OS ships with a large circular plastic lens hood (LH770-05) and it accepts 67mm filters.

A couple of notable concessions to the aggressive price-point are the lack of a removable tripod mount ring supplied in the box (although one can be purchased as an optional accessory), and the lack of any case or soft bag. We'd recommend buying both, which obviously pushes up the price.

Focal Range

At the 100mm focal length the angle of view is 24.4 degrees.

100mm

At the 400mm focal length the angle of view is 6.2 degrees.

400mm

Chromatic Aberrations

Chromatic aberrations, typically seen as purple or blue fringes along contrasty edges, are only conspicuous by their almost complete absence from our test shots.

Light Fall-off and Distortion

With the lens set to its maximum aperture, there is significant light fall-off in the corners at both ends of the zoom range. Stopping-down to f/11 virtually eliminates this. There's very little distortion to worry about.

100mm

400mm

100mm

400mm

Macro

The Sigma 100-400mm F5-6.3 DG DN OS isn't claimed to be a macro lens. It has a minimum focusing distance of 112cm/ 44.1inches and a maximum magnification ratio of 1:4.1. 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 Sigma 100-400mm F5-6.3 DG DN OS lens, Sigma employed an iris diaphragm with nine rounded blades, which has resulted in very 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 this lens is, we are providing 100% crops on the following pages.