The purpose of this purchase was to have a more open lens with short focal lengths as the Canon 18-135 bought with the camera (EOS 550D). The classic 50 mm focal length, is on a Canon APS-C focal length 35 mm (1.6 correction factor), 17-50 A goal is therefore well suited to the group and portrait photography. The objective is Canon corresponding to almost 1000 euros, I sought a cheaper alternative. Two goals could agree, Sigma and Tamron. Of course I read the comments here and the tests performed by different newspapers. The criticism that comes up most often is that of the front or back focus (focusing fault). So upon receiving this, I immediately made a very simple test of photographing a printed sheet with a 45 ° angle and openness 2.8. Verdict, correct focus with a very slight tendency to focus forehead. The tests show a loss of sharpness at maximum aperture at 50mm focal length, that is true but not outrageous. A 40 mm everything falls into place, same by stopping 50 mm 3.5. Otherwise the sharpness is very satisfying and correct bokeh. Another criticism, the shrill sound of the focus engine. We see it on youtube a video where the motor back and forth several times from one end to the other of its ramp. In reality, we mean just a little Bzzzt for less than one second and then fine adjustments are much more discreet. It is clear that noise might be a little less acute, but it is really not a problem. Another criticism concerns the size of the focus ring, it is true that it is a bit narrow. The lens comes with a lens hood (Canon thank you that sells its sunshield 30 euros, small meanness repeatedly denounced) and can be locked in the closed position (very helpful and we would also find it at Canon). Finally, a goal that responds well to what I expected, and at bargain prices
