Re: Tamron 17

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Tamron AF 17-50mm f/2.8 SP XR Di II LD Aspherical VC (Canon) - review / test Report
Lens reviews - Canon EOS (APS-C)

Review by Klaus Schroiff, published January 2010Special thanks to lớn Marcel Sahlmen for providing this lens!IntroductionThings have been busy in the standard zoom lens market lately - both Canon and Nikon have upgraded most of their lineup to image stabilized variants và the third-party gang follows albeit slowly. Sigma introduced their OS ("Optical Stabilizer") in a number of lenses and it seems as if Tamron is now next in line with their VC ("Vibration Compensation"). Tamron started the overhaul of their lineup with their extreme zoom lenses - the Tamron AF 18-270mm f/3.5-6.3 VC và AF 28-300mm f/3.5-6.3 VC. Regarding their sales volume these are their key lenses so they seem to lớn be pretty much convinced that their VC system is ready for prime time. The Tamron AF 17-50mm f/2.8 SP XR Di II LD Aspherical VC reviewed here is even more ambitious because large aperture IS/VC lenses are even less forgiving with respect to unique control issues (VC/IS is technically nothing else but a controlled decentering). The pricing is very competitive at around 550EUR/650US$ which is about a third less than the Canon EF-S 17-55mm f/2.8 USM IS - the undisputed king in this lens class (at least in Canon EF mount).
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The build chất lượng is typical for a consumer grade zoom lens although Tamron SP ("Super Performance") lenses are actually intended to target the high end market. Most of the lens is made of good chất lượng plastics based on a metal mount. The zoom ring operates quite smoothly. The focus ring has only a very short focus path so accurate manual focusing is a bit on the difficult side. It is somewhat anachronistic that the focus ring still rotates in AF mode - neither Canon USM nor Sigma HSM lenses show this effect anymore. The lens extends when zooming towards the long over of the zoom range and the supplied petal-shaped hood adds a little extra length. Thanks to lớn internal focusing, the front element does not rotate so using a polarizer remains easily possible. The lens is quite a bit bigger compared khổng lồ its non-VC sister lens although still smaller than the Canon EF-S 17-55mm f/2.8 USM IS.
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The Tamron AF 17-50mm f/2.8 VC still relies on a conventional AF micro-motor. Speed-wise this is not a problem because of the already mentioned short focus path (turning the focus ring by a ~40 degrees traverses the whole focus range) but AF operations are noticeable (noise-wise). The AF accuracy was a bit soso on our test DSLR. The AF performance in Live-View mode (contrast AF) is rather mediocre. Regarding the VC Tamron claims an efficiency of up lớn 4 f-stops. While we can confirm that the VC works very well we recommend lớn avoid exploiting this to the max due lớn the increasing number of outliers in field conditions.