Sigma 70-200mm F2.8 EX DG OS HSM
Category: Telephoto Lens
Conclusion - Pros
- Very sharp across the frame when stopped down
- Minimal color fringing/chromatic aberration of any description
- Fast, silent, accurate autofocus with manual override
- Very effective image stabilization
- Decent build quality
- Clever design tripod mount which is quick and easy to remove with the lens on the camera
Conclusion - Cons
- Somewhat soft and low in contrast at F2.8 towards the edges, especially on full frame cameras
- Can give somewhat harsh rendition of out-of-focus backgrounds at longer focus distances
- No focus limiter switch
- No weathersealing
- Susceptible to flare with direct light sources in or close to the frame
- Front-positioned zoom ring is inoperable when hood is reversed
- Depth of field scale inaccurate at close focus distances
The Sigma 70-200mm F2.8 EX DG OS HSM is a bold attempt to challenge the quality and functionality of some of the very best lenses on offer today - the fast image-stabilized telezooms from Nikon and Canon. Overall, it has to count as a success: the image quality is very decent, especially when stopped down a bit, and those crucial focusing and stabilization systems work well.
The first thing many will look at when considering such a lens is of course sharpness, and this is probably the Sigma's weakest suit in comparison to its peers, as the latest Canon and Nikon 70-200mm F2.8s have set the bar extraordinarily high. It tends to be very sharp in the center of the frame even wide open, but somewhat soft and low in contrast towards the corners. However it improves dramatically on stopping down, giving truly excellent results across the frame by F5.6 - F8. But overall, it can't quite match the extraordinary clarity of its more expensive rivals.
Of course, sharpness isn't everything in defining image quality. Of particular note is the almost complete lack of chromatic aberration, which presumably is due to the use of the latest 'FLD' glass in the lens's construction. The resultant absence of color fringing is important as it means the images look extremely clean right across the frame, and this has a strong positive impact on the overall perceived image quality. Distortion is well-controlled too, although vignetting is above average for the class on full frame. Out-of-focus backgrounds are generally rendered quite attractively too, although at longer focus distances they can become somewhat harsh.
The build quality is also impressive. You may not get the same bomb-proof metal construction and weathersealing as the (much more expensive) Canon and Nikon alternatives, but the lens feels well put-together with a high standard of fit and finish. It's also nice to see that Sigma has retained the clever tripod-mount ring from the previous design, which makes switching the lens on and off a tripod a breeze.
The lens's handling and ergonomics are, however, slightly unconventional, as a direct result of the optical design (which places the focusing group behind the zoom group). Most obviously, the zoom ring is situated towards the front of the barrel in a position more conventionally occupied by the focus ring, which is now placed more centrally. We had no real problems with this in normal use, but could envisage it being annoying to photographers who regularly use manual focus and are used to a more standard layout. The other irritation - and it's no more than that - is that the zoom ring is completely blocked and inoperable when the hood is reversed, which can hinder getting quick grab shots.
Another consequence of the rear-focus design is the increased minimum focus distance, and lower maximum magnification, compared to Sigma's previous 'Macro' 70-200mm F2.8 designs. This is worth bearing in mind of you shoot a lot at close distances, but to be honest we were never that impressed with the close-focus image quality of the older lens anyway, due to strong color fringing and focus shifts on stopping down.
Sigma has clearly been working hard in the lens's stabilization and focusing systems, and we found that both performed extremely well. The HSM focusing was always an attractive feature of Sigma's older 70-200mm F2.8, and that certainly remains the case here. We spent an evening shooting fast-moving track cyclists using the Canon EOS 7D and the return of in-focus keepers was very impressive, even when tracking focus at 7 fps. Likewise with static subjects focusing was fast and highly accurate, with no evidence for any systematic errors at all. However sports shooter should be aware that there's no focus limiter switch.
Of course the big news with this lens is the addition of optical stabilization, for the first time in a third party fast telezoom. We're pleased to report that it works very well - it's perhaps not quite as adept as the very best systems from Canon and Nikon at providing absolutely pixel-sharp results at slower shutter speeds, but you have to look very closely to notice. For most output sizes, the results will be as close as makes no practical difference.
Aside from this, there are just a couple of nitpicks. Sigma unusually marks a depth of field scale on the lens, which is only really for use at 70mm, but in this case it's highly inaccurate and over-optimistic at close distances. Now we can't imagine many users will rely on this for setting focus as a matter of course, but any who are tempted by the generous depth of field apparently on offer will be disappointed. We also found that the APS-C hood extension, while a good idea in principle, was over-fiddly to use in practice, with a bad habit of ending up stuck inside the main hood (it really needs to lock onto the lens). However it must be stressed that neither of these points make the lens any less useful than competing designs - it's more a case of Sigma trying to offer something extra to its customers, just in a not-wholly-successful fashion.
Overall, then, the 70-200mm F2.8 OS HSM is a fine lens, that offers functionality and image quality close to the equivalents from Canon and Nikon at a distinctly lower price. For some users, the features that it lacks (such as weathersealing and a focus limiter switch), along with the slightly less impressive optics, may well be deal-breakers. Likewise, it almost goes without saying that Sony and Pentax owners happy to rely on their camera's in-body image stabilization systems will find better value elsewhere. But for anyone else, it's worth a very serious look.
Ergonomics and Handling
Sigma's latest image-stabilized fast telezoom offers a fine option for budget-conscious buyers, with a unique combination of features for the price. It can't quite match its Canon and Nikon equivalents, but then again it's not as expensive either.
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