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Canon EF-S 17-85mm coverage, wide angle with Canon EOS 350D / XT
To compare actual coverage we shot the same scene with each lens within a
few moments of each other; the lenses were set to their widest then longest
focal lengths and the camera mounted on a tripod to ensure a consistent
position.
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 f4~5.6 IS USM |
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Canon EF 17-40mm f4.0L USM |
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Canon EF-S 18-55mm f3.5~5.6 |
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17-85mm at 17mm
(27mm equiv using 350D / XT) |
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17-40mm at 17mm
(27mm equiv using 350D / XT) |
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18-55mm at 18mm
(29mm equiv using 350D / XT) |
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 f4~5.6 IS USM |
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Canon EF 17-40mm f4.0L USM |
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Canon EF-S 18-55mm f3.5~5.6 |
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17-85mm at 85mm
(136mm equiv using 350D / XT) |
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17-40mm at 40mm
(64mm equiv using 350D / XT) |
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18-55mm at 55mm
(88mm equiv using 350D / XT) |
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%.
Canon EF-S 17-85mm
Image Stabilisation OFF
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Canon EF-S 17-85mm
Image Stabilisation ON |
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85mm (136mm equiv), 1/4, f32, 100 ISO |
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85mm (136mm equiv), 1/4, f32, 100 ISO |
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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