The Canon EF-S 17-85mm f/4-5.6 IS USM lens was put on the market by the Japanese company in the period between 2004 and 2009 and was designed exclusively for APS-C format cameras. It was immediately appreciated by professional photographers for its focusing driven by an excellent ultrasonic AF motor and for the presence of image stabilization. The results of the shots, based on these characteristics, are obviously of notable quality. Let's start first by highlighting the good workmanship of the construction materials which allow for a decided solidity of the lens which is combined with lightness, a fundamental element when it must be used for a long time resulting in arm fatigue. The strong point of the Canon EF-S 17-85mm f/4-5.6 IS USM lens is its focal range which makes it truly suitable for any situation. The focusing speed is also excellent, thanks to the very reactive motor and capable of obtaining shots characterized by very minimal distortion. However, the best focusing performance occurs in diffuse light conditions while the images are slightly penalized when the brightness does not appear sufficient. In general, very sharp shots, characterized by high contrast and a wide range of colors which are overall very lively. Ultimately an ideal lens for every circumstance and suitable for both professional photographers and those who are entering the world of reflex cameras for the first time.