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Canon EF-S 17-85mm coverage, wide angle with Canon EOS 350D / XT At first glance the three lenses on test appear to deliver roughly identical wide-angle coverage, but look a little closer and there are differences. The EF-S 18-55mm unsurprisingly delivers a slightly reduced field of view, but interestingly the EF-S 17-85mm captures a slightly wider field than the 17-40mm despite having the same quoted wide focal length. The 17-40mm is the only one of the three which can also work on a full-frame body though, delivering considerably wider views and supporting possible future body upgrades.
Canon EF-S 17-85mm coverage, telephoto with Canon EOS 350D / XT With each lens zoomed into their longest focal lengths, the differences are unsurprisingly much greater. The budget 18-55mm enjoys a noticeably longer reach than the 17-40mm, but neither come close to the 17-85mm when it's fully zoomed-in. While the other two lenses are still essentially capturing wide shots of the scene in question, the 17-85mm is able to fill the frame with much closer views. It may not make a great difference to distant wildlife or sports photography, but is useful for general travel and portrait compositions. See our Canon EF-S 17-55mm review for more coverage comparisons.
Canon EF-S 17-85mm Image Stabilisation The Canon EF-S 17-85mm features Image Stabilisation (IS) facilities which claim up to three stops of compensation - this allows you to handhold much longer exposures than normal and is a boon whether you're shooting under dim conditions or want to close the aperture right down for very large depths-of-fields. For example, if the slowest exposure you could safely handhold at a certain focal length was, say, 1/60, three stops of compensation should allow you to enjoy the same result at 1/8. This would allow you to get the shot you wanted without having to resort to higher sensitivities and increased noise as a result. With IS switched on from the side of the lens, the system activates as you half-press the shutter release. As with other IS lenses, there's a faint click after which the composition through the viewfinder appears to float gently. The system deactivates with another faint click around two seconds after removing your finger from the shutter release. In practice the IS system proved very effective. Below are two examples taken moments apart with the lens fully zoomed-in to 85mm, and therefore operating at an effective focal length of 136mm. With the aperture closed to f32 at 100 ISO, the shutter speed was 1/4 of a second. We cropped an area from each image measuring 564x272 pixels, then reduced it to 282x136 pixels for reproduction here; you’re therefore viewing the images here at 50%.
The image without stabilisation, above left, is unsurprisingly shaky. With stabilisation enabled though, it was possible to handhold the same composition and deliver a sharp result. To achieve the same result without stabilisation under the same conditions required a shutter speed of 1/30, confirming three stops of compensation. For more examples of IS in action, check out our Gallery, where you'll see it allowed us to shot under very low light without incurring camera-shake. It's an extremely valuable feature, although be warned, IS will drain your batteries faster than a lens without. |
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