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To compare actual coverage we shot the same scene with the 17-55mm, 17-85mm and 18-55mm lenses within a few moments of each other using an EOS 400D / Rebel XTi; the camera was mounted on a tripod to ensure a consistent position. Here the lenses were set to their widest focal lengths. With all three images opened alongside each other in Photoshop, the 17-55mm captures a fractionally wider field than the 18-55mm as expected, although interestingly the 17-85mm squeezes noticeably more still; this is apparent even on our shrunken examples below, where the 17-85mm sample is pictured in the middle. Our Canon 17-85mm review also showed it capturing a slightly wider field than the 17-40mm L model.
Canon 17-55mm coverage, telephoto Next up came the telephoto-end of each lens. Again to compare actual coverage we shot the same scene with the 17-55mm, 17-85mm and 18-55mm lenses within a few moments of each other using an EOS 400D / Rebel XTi; the camera was mounted on a tripod to ensure a consistent position. Here the lenses were set to their longest focal lengths. Here the longer reach of the 17-85mm is clear, and gives it greater compositional versatility than the pair which top-out at 55mm. As for them, the 17-55mm delivered a fractionally tighter field than the 18-55mm when zoomed-into 55mm, although it was extremely close.
This clearly allows you to shoot under much lower light conditions without needing a tripod, or increasing the sensitivity and compromising noise levels as a result. The 17-55mm’s bright f2.8 aperture helps even more in this regard, making it an excellent lens for anyone who works in low light. Like other Canon wide zooms with IS, there’s only one mode available with a switch on the side of the lens to switch it on or off. The system kicks in with a faint click when you depress the shutter halfway and stays on for a few seconds before deactivating to save power. To test its effectiveness we shot the same macro scene zoomed-into 55mm with and without IS enabled; this was working at an effective focal length of 88mm. Below are two examples of a handheld macro composition taken with and without IS, using a very slow shutter speed of half a second. We've cropped the original images to 1728x1152, thereby showing around one quarter of the original, then reduced them to 282x188 pixels for reproduction here. Viewed at 100%, the shot with IS is perfectly sharp.
As with all anti-shake systems, the effectiveness of IS varies between photographers and the particular shooting conditions, but its benefits are still clear. And coupled with the 17-55mm’s f2.8 aperture you can now shoot under conditions you’d previously consider impossible. For example with the lens at 17mm and the 350D / Rebel XT set to 1600 ISO we managed to shoot sharp portraits at f2.8 in a very dark bar environment using exposures as long as one second. This was only possible with the image stabilisation and f2.8 aperture of the lens – along with subjects who kept very still of course! Canon 17-55mm with built-in popup flash
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