Sigma 17-70mm F2.8-4 DC Macro OS HSM | C
Category: Normal Lens
Conclusion - Pros
- Useful combination of zoom range and relatively fast aperture
- Very good image quality across most of the range
- Compact size
- Reasonably fast and near-silent autofocus
- Effective image stabilisation
Conclusion - Cons
- Somewhat weak image quality at wideangle (soft corners and chromatic aberration)
- Macro shooting a little impractical (very short working distance)
The Sigma 17-70mm F2.8-4 DC Macro OS HSM is designed as an upgrade to the 18-55mm kit lenses supplied with most SLRs, and offers an interesting middle ground between fast zooms of the 17-50mm F2.8 type, and extended-range zooms in the 16-85mm class. In effect you get a bit of both - a usefully-extended range compared to those typical kit zooms, and a faster maximum aperture for better low light capability and a bit more creative control over depth of field.
In practice, the 17-70mm turns out to be an excellent choice if you've grown out of a kit zoom and want something a bit better. It offers generally better optics, a broader zoom range, and of course that faster aperture. But this all comes in a package that's surprisingly compact, and doesn't take up too much extra space in your camera bag. It's not as light as a kit zoom, but not excessively heavy either.
The lens's focusing and image stabilisation systems work well too. Autofocus is pretty fast, and near-silent when shooting stills; we've seen no obvious problems with accuracy either. Likewise the OS system is silent in operation, and works generally very well; we generally got about three stops worth of stabilisation out of it (although as usual, it's best to take a few replicate shots when relying on OS for sharpness).
The 17-70mm's main weakness is its image quality at wideangle; here it suffers from somewhat soft edges which don't sharpen up on stopping down, coupled with quite strong chromatic aberration. The latter can easily be fixed in post-processing if you shoot RAW, but note that only Nikon SLRs will correct it in their JPEG output. Softer edges are more difficult to deal with, so if you spend a lot of time shooting detailed landscapes at wideangle, this may not be the best choice of lens.
The 'Macro' in the lens name points to its impressive-on-paper close focusing, but we found this to be a bit less useful than you might hope. The numbers certainly look good - 22cm minimum focus, 0.37x magnification - but in practice this equates to a very short working distance between the lens and the subject. This means you'll often find yourself blocking out your own light, or casting a visible shadow on your subject. As it happens, those lowly 18-55mm kit zooms offer similar magnification with more practical working distances. So despite the 'Macro' label, we wouldn't necessarily recommend this lens if close-ups are a specific priority.
The Final Word
Sigma's faster-than-average 17-70mm lenses have long had a pretty good reputation as kit zoom upgrades, and the latest iteration continues in this tradition. Its combination of extended focal length range and faster aperture offers useful extra compositional flexibility compared to an 18-55mm F3.5-5.6, and the optics are overall better too. It's not perfect, and in particular may not be the best option if you shoot a lot at wideangle or close-up. But it's very good indeed, and a great choice for SLR owners looking to expand their horizons beyond the kit zoom.
Ergonomics and Handling
Sigma's latest 'C' badged 17-70mm F2.8-4 is an excellent upgrade option for SLR shooters who've outgrown their kit zooms, and are looking for better image quality and more creative flexibility. It offers a fine balance of zoom range and maximum aperture, while still being highly portable. Autofocus and image stabilisation both work well, but image quality at wideangle isn't the best.
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