Sigma 24-70mm f/2.8 DG OS HSM Art Review

Sigma 24-70mm f/2.8 DG OS HSM Art Handling and Features

The lens looks big and bulky and this is reflected in its fairly hefty 1020g weight. It does balance well on the Canon EOS 5DS R, but there is no escaping the overall weight and a camera sling may well the best way to carry this for any length of time. Operationally, it immediately becomes apparent that Canon style lenses operate both zoom and focusing in the reverse direction to Nikon and Pentax. This is not a problem as such, but something that anyone switching to Canon from the other two would need to get used to. The lens is available in Canon, Nikon and Sigma mount versions, with the option of having the mount changed should the photographer change systems at some future point. The Nikon version has the electromagnetic E type diaphragm, so it is compatible with all the latest bodies. Some earlier Nikon bodies will only be usable at open aperture.

Commencing with the provided petal lens hood, this clips firmly into place. There is no locking lever, but the hood seems secure enough. There is an 82mm filter thread.

The zoom ring is clearly marked with various focal lengths. It is firm in action and does change the length of the lens as we zoom in. The focusing ring is immediately behind this and is electronic in operation, operating internal focusing. Closest to the camera body we have a distance scale under a small clear window, marked in feet and metres. There is no depth of field scale.

At the same point, there are two switches on the lens. The first selects the focusing mode. AF setting is self-explanatory, and it also allows for further manual tweaks when AF has locked on and the shutter release button is held at the halfway point. MO setting is similar but now allows continual manual adjustments even when AF is operating. Finally, MF is fully manual focus. Focusing in AF modes is fast, silent and very reliable. There is no hunting and the AF locks on correctly every time. Focusing is down to 0.37m (15 inches), a maximum magnification of 1:4.8.

The second switch selects on/off for the optical stabilisation and testing it out indicates that 3 or 4 stops advantage is a reasonable expectation. This of course enormously extends the potential of low light handheld photography, something that we are rapidly becoming used to.

Optically, the lens construction is 19 elements in 14 groups. This includes 3 SLD (Super Low Dispersion) and 4 Aspheric elements. The diaphragm comprises 9 rounded blades, designed to improve the bokeh of the lens, the softness of gradation of the out of focus background areas in an image.

The lens mount has a rubber gasket and the mount only is described as dust and splash proof. This no doubt helps to prevent ingress of moisture into the camera body, but the lens itself is not weather sealed. The instructions provided are quite clear that efforts should be made to keep the lens dry, although looking at the tightness and high quality of construction there do not seem to be any glaringly weak spots that might not take a splash or two. We go out in the rain at our own peril and a weather shield might be in order.

Compatibility with the Sigma USB dock means that some adjustments and upgrades can be made using this, a convenient feature. The lens is also compatible with the Mount Converter MC-11, which enables the Canon and Sigma fit versions to be used with Sony E-mount mirrorless cameras.

Moving up from a kit zoom lens, the 24-70mm may well seem big and heavy. Some of this is a consequence of it being a full frame lens, some the fast and constant f/2.8 maximum aperture and some the high quality of the construction. There is no escaping this, but on the other hand, the handling is excellent generally and the package is reassuringly solid.

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