Before that I used Canon 18-200 mm f/ 3.5-5.6 IS and Sigma DC 18-50 mm f/ 2.8 EX in conjunction with 50D. I immediately felt its advantage in sharpness, but the main thing is the accuracy and speed of focusing. In the picture, 17-55 does not stand out in particular. Changed the device to 7D. I use Canon 85 F / 1.8, Sigma 85 F / 1.4, Canon 70-200 F / 4L, Canon 80-200 F / 2.8 but I wear 17-55 for important events because, the smallest percentage of defects in focus. I shoot mainly events and reporting. There are many other much better lenses for staged photography, but for reporting, 17-55 F / 2.8 for crop is the most RELIABLE ! Three years of use of the lens only confirmed its superiority.
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