The Sigma 17-70mm f/2.8-4 DC Macro OS HSM is one of those lenses that hits the middle of the price range and offers a lot of features in one package. Specifically designed for APS-C sensors, the equivalent focal length comes in at 25.5-105mm, which still gives a very usable range, along with a macro mode for good measure.
Wide-angle to relatively telephoto and a variable aperture of f/2.8-f/4, means there should be plenty of facility in this lens for the budding photographer. But, can the lens provide all the duties it offers in good quality and how does it measure up to the rest of the market?
For a lens that covers a relatively wide focal range, the Sigma 17-70mm f/2.8-4 DC Macro OS HSM weighs in at only 465g. It’s very compact, only extending when it’s at its most telephoto.
The lens barrel itself is what you would expect from a midprice offering, being made of solid TSC (Thermally Stable Composite). There’s also a brass bayonet mount, which should improve the lense’s longevity and provide a good seal against environmental nasties.
On the lens barrel is a simple layout of features, starting with the focus ring, which is ridged and has focal length marks going from 17, 24, 28, 35, 50, and 70. When the lens barrel extends, there are also macro markers along the barrel with simple distance markers in feet and meters. The lens barrel also has the pre-requisite AF/manual focus switch and a switch for image stabilization.
Internally, the Sigma 17-70mm f/2.8-4 DC Macro OS HSM has 16 elements arranged in 14 groups, with a seven blade rounded diaphragm going from f/2.8-f/4 to f/22, which should provide reasonable bokeh quality. The elements consist of an F low dispersion (FLD) and Special Low Dispersion (SLD) element and a super multi-layer coating for reducing things like reflections and lens flare. Upfront is a 72mm filter thread which doesn’t rotate when focusing and comes with its own petal-shaped lens hood.
One thing to note is that Sigma has built-in a very usable focal range, which should cover most bases. Even on a crop sensor body, the 25.5-105mm still goes relatively wide-angle to telephoto, which should make this lens applicable for anything from architecture to portraits. Thus, giving plenty of scope to practice in the most usable focal lengths.
The Sigma 17-70mm f/2.8-4 DC Macro OS HSM in Use
The focusing system of the Sigma 17-70mm f/2.8-4 DC Macro OS HSM consists of an integrated HSM (Hyper Sonic Motor) which is both quick and quiet. There wasn’t much hunting for focus, unless in very low light conditions, so there are no complaints in this area of the lens’ workings.
When it comes to overall sharpness, the lens performs differently at the extremes of focal length. At 17mm the lens is at its sharpest in the center and edges between f/4 and f/11, dropping off after f/16 due to diffraction.
At 50mm center sharpness looks its best from f/5.6 to f/11, with the edges being the most sharp at f/8. The same is true and 70mm where the center sharpness is at its best at f/5.6, tailing off after f/16. Edge softness at this focal length being at its best from f/8 to f/11.
The lens does display some optical anomalies, but they are not as prominent as expected. Chromatic aberration rears its head when the aperture is wide open, displayed as purple or blue fringing. These are easily correctable in software, but it’s always good to be mindful to watch out for high contrast areas where you will see this affected the most.
Vignetting is less than expected in the corners, but is most obviously seen at the widest aperture and focal length. Stopping down to f/8 almost gets rid of the effect, but it’s still very obvious when the lens is at its widest.
As the lens has a macro mode, it’s worth checking out to see how extremely small images can be reproduced. The lens doesn’t have a full 1:1 ratio, but a 1:2.8 ratio with a minimum focusing distance of 22cm.
At the 70mm end, this comes in at 5.52cm. The resulting images aren’t going to reproduce the most microscopic subjects, but its still quite capable of getting everything in sharp focus, bearing in mind the depth of field when using the widest aperture.
For bokeh effects, a wide-angle zoom isn’t the most obvious choice, but the lens is quite capable of producing smooth background blur. Highlights are reproduced with nice rounded shapes and colors only start to get harsh when the background is very busy.
Apart from when the lens has its aperture wide open and at the widest focal length, the lens produces very sharp images with a good degree of contrast and saturation. The macro mode also works very well and adds another level of functionality to an already well-rounded lens.
How Does It Compare?
If you’re after a zoom lens that can cover relatively wide-angle to telephoto, then one possible alternative is the Canon EF-S 17-55mm f/2.8 IS USM. This is a middle-of-the-road offering by Canon, which doesn’t have the same focal range as the Sigma 17-70mm f/2.8-4 DC Macro OS HSM, but it does have comparable optics.
In the real world, 17-55mm on a crop sensor body can still provide a good workable range and just like the Sigma, the Canon has image stabilization. It cost slightly more than the Sigma, but if you own a Canon body, sticking with the same brand maybe a good option.
Staying in the Canon camp, there is the Canon EF 24-70mm f/4L IS USM, which is a jump up in optical quality, but costs more. It may be only f/4, but it’s definitely sharper at this aperture than the rest.
|Sigma 17-70mm f/2.8-4 DC Macro OS HSM||Canon 17-55mm f/2.8 IS|
|Optics||16 elements/ 14 groups||19 elements/ 12 groups|
The Sigma 17-70mm f/2.8-4 DC Macro OS HSM is a well-rounded lens that provides a macro mode for good measure. As long as you stop down from f/4, images come out very sharp and the lens can even produce respectable bokeh from the seven-blade aperture.
There are distinct amounts of vignetting when the lens is wide open, along with some barrel distortion at 17mm, but luckily each can be corrected in post-processing. The build quality of the lens is also very good and considering the price point, this is a great step up from a kit lens.