Canon EF-S 17-85mm f/4-5.6 USM IS - Retest @ 15MP / Review
Lens Reviews - Canon EOS (APS-C)
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Special thanks to Rainer Temme for providing the lens for testing!


The Canon EF-S 17-85mm f/4-5.6 USM IS has already been tested on the old EOS 350D (@ 8MP) but from a consumer point of view it is one of the key lenses in the Canon lineup so let's have a look how it performs on the EOS 50D (@ 15MP) again. Most of the old article has been copied for obvious reasons.

The lens is often considered as an upgrade path from the basic EF-S 18-55mm f/3.5-5.6 IS kit zoom. Obviously it adds quite a bit of range, a 2nd generation image stabilizer and a ring-type USM drive with full-time manual focusing. The EF-S naming refers to Short-backfocus design which is only compatible to APS-C EOS SLRs starting with the EOS 300D (Digital Rebel). EF-S lenses have a protruding rear element which requires a special mirror design to avoid a collision of mirror and the rear part of the lens. The principal idea is the reduce the distance of lens to the sensor which can translate to a better lens design - on paper at least.

On Canon APS-C DSLRs its zoom range is equivalent to ~27-136mm (5x ratio) on full frame cameras so it can be considered as an allround zoom lens. Its first obvious drawback is the rather slow max. aperture resulting in very limited creative potential regarding depth-of-field aspects. Same goes for low light potential but the image stabilizer (IS) is capable to overcome this to a certain degree. The 2nd generation IS allows safe hand-holding at speeds up to three stops slower than otherwise possible. Remember that slow shutter speeds can have negative side effects regarding moving objects (motion blur) so IS is not the holy grail of photography but nonetheless it is still highly desirable.

As you can see in the product shots above the lens extends during zooming being shortest at 17mm and reaching its max. length at 85mm. It has a so-called duo-cam zoom system with two inner lens tubes. Regarding its rather high price tag the build quality isn't overly impressive with a couple of squeaking parts and slightly wobbling duo-cams. The plastic shell feels somewhat thin. The zoom and focusing action is quite decent. All-in-all the construction quality is slightly better than the EF-S 18-55mm f/3.5-5.6 IS but this is nowhere near L class quality. The lens seems to have a tendency to suck dust into the inner chamber.

The lens has a very fast and near silent USM (ultrasonic) AF drive including full-time manual focusing (FTM) in one-shot AF mode. The AF is extremely accurate on the EOS 50D with this lens. The minimal focus distance is 0.35m resulting in a max. magnification of 1:5 at 85mm. The front element does not rotate so using a polarizer is no problem.

Equiv. focal length27-136 mm (full format equivalent)
Equiv. aperturef/6.4-f/9 (full format equivalent, in terms of depth-of-field)
Optical construction17 elements in 12 groups inc. 1x aspherical element
Number of aperture blades6 (rounded)
min. focus distance0.35 m (max. magnification ratio ~1:5)
Dimensions79 x 92 mm
Weight475 g
Filter size67 mm (nonrotating)
Hoodoptional, petal-shaped, snap-on type
Other featuresIS (Optical Stabilizer)

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