The canon EF-S 17-55mm f/2.8 is usm is a standard zoom lens put on the market by the Japanese company starting from the year 2006 . It is characterized by an automatic image stabilizer at three stops and by a focus via ultrasound AF motor (Ring-USM) with a minimum required distance of about 35 centimeters and a maximum magnification of 0.17x . From the most expert and many customers who have had the pleasure of trying it, it was defined as one of the best standard lenses around and ideal for photographs taken in environments with low lighting levels (artificial or natural) and for photographs defined in jargon freehand . It includes an opening up to f/2.8 and some elements ud (Ultra Low Descersion) reserved for the far more professional and expensive models of the series L . Among its defects, however, we find an excessive level of flare when it is used without the chastener included or with other medium-low quality UV filters. Another small flaw, albeit very contained, is represented by the chromatic aberrations , a problem relating to almost all the large large focal ones (especially the corners and edges) and also from its size slightly beyond the average (weighs about 640 grams ). The Canon EF-S 17-55mm f/2.8 is usm is perfectly compatible with the reflex APS-C Canon EF .