Canon EF-S 17-85mm f/4-5.6 USM IS - Test Repo...

Canon EF-S 17-85mm f/4-5.6 USM IS - Test Report / Review
Lens Reviews - Canon EOS (APS-C)
Article Index
Introduction
Analysis
Sample Images & Verdict
Page 1 of 3
Special thanks to Marcus Erne for providing a second sample for testing!
Introduction
The Canon EF-S 17-85mm f/4-5.6 USM IS is one of the more interesting consumer standard zoom lenses in the market. It is often considered as an upgrade path from the basic EF-S 18-55mm f/3.5-5.6 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 ... at a price naturally. 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 such as the EOS 350D (used for testing) 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. The lens construction is made of 17(!) elements in 12 groups including 3 aspherical elements. Its aperture mechanism features 6 circular aperture blades. At a size of 79x92mm and 475g it is relatively compact but it is quite a sight when extended to 85mm with attached lens hood.
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 surely better than the EF-S 18-55mm f/3.5-5.6 but this is nowhere near L class quality. As usual the lens has been loaned by a kind Photozone reader so the tested sample has seen the field already. The lens has a tendency to collect 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 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.
Distortions
The lens broke a new record here - at 17mm it shows the most pronounced barrel distortions of all (supposedly) corrected lenses tested to date and that's by quite a margin. As you may observe in the sample shot below this is not only theory ...

Typical for all zoom lenses the barrel distortions change to pincushion distortions when zooming towards the long end of the zoom range. At about 24mm both forces even out technically though there're still some wavy-like distortions left here. At 50mm and 85mm the level of pincushion distortions remain relatively slight so for most of the zoom range the performance is actually pretty decent.
Move the mouse cursor over the focal length text marks below to observe the respective distortions
17mm24mm50mm85mm

 
The chart above has a real-world size of about 120x80cm or 60x the focal length. Expect higher distortion levels towards closer focus distances.
Vignetting
So far most of the tested lenses were full-frame variants. APS-C DSLRs such as the EOS 350D can take advantage of the sweet spot of the lens here usually resulting in pretty decent vignetting figures. However, the EF-S 17-85mm is a native APS-C lens with a reduced image circle so it is not surprising that vignetting is far more pronounced exceeding 1.3EV at 17mm @ f/4 and 0.7EV at 85mm @ f/5.6. As usual stopping down a little helps to reduce the problem significantly.

MTF (resolution)
The lens produced a relatively decent performance in the lab but there're clearly some flaws here. Throughout the zoom range the center performance is generally great approaching the resolution limits of the EOS 350D (8 MP). The corners at about 70% off the center can be considered as good. Due to the reduced image circle a closer look at the extreme corners at about 90% off the center revealed some problems. At 17mm these extreme corners showed only an okayish quality and stopping down did not really improve the issue. At 24mm the extreme corners recover towards medium apertures.
The 1st sample of the lens suffered from a centering defect and a test of a 2nd sample did produce better results specifically regarding the center performance and the border performance towards the tele end.
Below is a simplified summary of the formal findings. The chart shows in line widths per picture height (LW/PH) which can be taken as a quantity for sharpness. If you want to know more about it you may check out the correspondingImatest Explanations.

Chromatic Aberrations (CAs)
Chromatic aberrations (color shadows at harsh contrast transitions) can be a significant problem from 17mm to 50mm where the average CA pixel width at the image corners can exceed 1.4 pixels. Interestingly the 2nd tested sample of the lens performed better here specifically at 17mm. At 85mm CAs are generally a non-issue.
Sample Shots
Ok, finally here're some sample shots taken with the EOS 350D. These JPEGs were RAW-converted via RSE which auto-corrects most chromatic aberrations.
Click on a thumbnail to view the original file (opens in a separate window). Please note that the originals are FULL SIZE samples (=several megabytes) thus requiring a significant amount of bandwidth so please take care of the limited resources here.
Make Canon
Model Canon EOS 350D DIGITAL
ISO Speed 200
Focal Length 53.0mm Exposure Data: f/10.0 @ 1/60s
Size 3472x2312
Make Canon
Model Canon EOS 350D DIGITAL
ISO Speed 400
Focal Length 85.0mm Exposure Data: f/9.0 @ 1/125s
Size 3472x2312
Make Canon
Model Canon EOS 350D DIGITAL
ISO Speed 200
Focal Length 85.0mm Exposure Data: f/8.0 @ 1/160s
Size 3472x2312
Make Canon
Model Canon EOS 350D DIGITAL
ISO Speed 200
Focal Length 44.0mm Exposure Data: f/11.0 @ 1/50s
Size 2312x3472
Make Canon
Model Canon EOS 350D DIGITAL
ISO Speed 400
Focal Length 85.0mm Exposure Data: f/8.0 @ 1/500s
Size 3472x2312
Make Canon
Model Canon EOS 350D DIGITAL
ISO Speed 100
Focal Length 50.0mm Exposure Data: f/9.0 @ 1/640s
Size 2312x3472
Make
Model Canon EOS 350D DIGITAL
ISO Speed 100
Focal Length 38.0mm Exposure Data: f/9.0 @ 1/400s
Size 2312x3472
Verdict
The EF-S 17-85mm f/4-5.6 USM IS is a lens that promises many things. It is certainly a very versatile standard zoom with a long zoom range and an image stabilizer that can save the day in many situations. However, the build quality is somewhat disappointing and optically it is also something of a mixed bag. The lens is very sharp in the image center throughout the range but at the wide-end the extreme corners leave something to be desired. The 17mm setting also suffers from rather extreme distortions and rather hefty vignetting @ f/4. Finally chromatic aberrations aren't really something to rave about either.
So at the end of the day the lens is a tad better than the cheapo EF-S 18-55mm f/3.5-5.6 but it can't really compete with the new EF-S 18-55m f/3.5-5.6 IS or the EF 17-40mm f/4 USM L. The key feature of the EF-S 17-85mm f/4-5.6 USM IS remains its versatility. While this may sound a little sceptical I should note that I preferred the lens compared to other higher quality options during testing - it is simply a darn convenient lens and despite the flaws it can produce very decent images as you can see from the samples - at least with a little tool support.
Optical Quality:
Mechanical Quality:
Price/Performance: