Canon EF-S 17-55mm f/2.8 USM IS - Review / Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)

Distortion

The EF-S 17-55mm f/2.8 USM IS exhibited average distortion figures for a lens in this class. As expected there is relatively pronounced barrel distortion (2%) at 17mm which evens out very shortly beyond. At 24mm there is already marginal pincushion distortion which increases continuously towards the long end of the zoom range (1.15%).

17mm:

24mm:

35mm:

55mm:

The chart above has a real-world size of about 120x80cm.

Vignetting

The EF-S 17-55mm is a reduced image circle lens and these lenses tend to produce higher vignetting figures. Unfortunately the lens is no exception to the rule. At f/2.8 the lens shows very pronounced vignetting around 1EV at all focal lengths. Stopping down helps to reduce the problem and from f/4 it's reasonably well controlled. However, it is a weak spot of this lens.

MTF (resolution)

Unlike most other dedicated APS-C zooms the EF-S 17-55mm f/2.8 USM IS delivered a very impressive performance throughout the zoom range. In fact the center resolution of the lens is among the very best tested to date (incl. fix-focals) and it probably exceeds the limits of the 8 MP sensor of the EOS 350D (used for testing). The lens is also capable to deliver corner to corner sharpness though there's (naturally) a little penalty at the image borders. However, even the extreme corners stay in very good territory and stopping down helps to lift the figures even further. There's a marginal drop in performance at 55mm at f/2.8 but even here there's little to worry about.

The lens showed a slight degree of field curvature at 17mm.

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Please pay attention to the new scale of [650,2150] which will be used for all EOS tests from now on.

Chromatic Aberrations (CAs)

Chromatic aberrations (color shadows at harsh contrast transitions) tend to be a weak spot of most zooms in this range. However, the EF-S 17-55mm f/2.8 USM IS exhibited an unusually moderate degree of border CAs well below the 1 pixel barrier even at the 17mm setting.




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