Canon ef

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Review by Klaus Schroiff, published October 2005Special thanks lớn Marcus Erne for providing a second sample for testing!IntroductionThe Canon EF-S 17-85mm f/4-5.6 USM IS is one of the more interesting consumer standard zoomlenses 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 USMdrive with full-time manual focusing ... At a price naturally.The EF-S naming refers to lớn Short-backfocus design which is only compatible toAPS-C EOS SLRs starting with the EOS 300D (Digital Rebel). EF-S lenses have a protruding rearelement which requires a special mirror design to lớn avoid a collision of mirror và the rear partof the lens. The principal idea is the reduce the distance of lens lớn the sensor which cantranslate lớn a better lens design - on paper at least.
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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 creativepotential regarding depth-of-field aspects. Same goes for low light potential but the imagestabilizer (IS)is capable khổng lồ overcome this khổng lồ a certain degree. The 2nd generation IS allowssafe hand-holding at speeds up khổng lồ three stops slower than otherwise possible. Remember thatslow shutter speeds can have negative side effects regarding moving objects (motion blur) soIS is not the holy grail of photography but nonetheless it is still highly desirable.As you can see in the hàng hóa shots above the lens extends during zooming being shortest at17mm và reaching its max. Length at 85mm. It has a so-called duo-cam zoom system with twoinner lens tubes. The lens construction is made of 17(!) elements in 12 groups including 3aspherical elements. Its aperture mechanism features 6 circular aperture blades. At a sizeof 79x92mm & 475g it is relatively compact but it is quite a sight when extended to 85mmwith attached lens hood.Regarding its rather high price tag the build quality isn"t overly impressive with acouple of squeaking parts và slightly wobbling duo-cams. The plastic shell feels somewhatthin. The zoom and focusing action is quite decent. All-in-all the construction qualityis 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 losingravidos.com reader so the tested sample has seenthe field already. The lens has a tendency to lớn collect dust into the inner chamber.
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The lens has a very fast and near silent USM (ultrasonic) AF drive including full-timemanual focusing (FTM) in one-shot AF mode. The minimal focus distance is 0.35m resultingin a max. Magnification of 1:5 at 85mm. The front element does not rotate so using a polarizeris no problem.