The Canon EF-S 17-55mm f/2.8 IS USM is a premium fast mid-range zoom lens designed soley for EF-S mount EOS digital cameras*. The zoom range starts moderately wide angle, goes through the normal, and ends just in the start of the portrait range. The 17-55mm focal length range used on an APS-C body produces a field of view approximately equivalent to the field of view a 27-88mm focal length range would produce on a full frame camera.
Image quality is quite good, the optical formula of 19 elements in 12 groups is well corrected and includes three aspherical and one UD (Ultra low Dispersion) elements. Engineers can optimize wide angle optical perfomance for the the APS-C format by not having the design constraints of a larger image circle or longer back focus that full frame lenses require.
The large f/2.8 maximum aperture produces a brighter viewfinder image, makes shooting in lower lighting or with faster shutter speeds easier, and allows more background blur than a smaller aperture lens. The circular aperture produces pleasing specular highlights.
Autofocus is responsively and quietly produced by a Ring Type USM (UltraSonic Motor) featuring full time manual focus override.
The built-in IS (Image Stabilization) system improves hand held images by reducing loss of sharpness due to camera shake, a real bonus when you can't carry or use a tripod.
Many photographers consider this Canon's best general purpose (non-telephoto) lens for APS-C cameras. It's very solid choice any kind of photography, a balance of optimal image quality and useful versatility.
Available accessories include the recommended EW-83J Lens Hood, LP-1219 Soft Lens Case and 77mm filters.
*Designed exclusively for APS-C format sensors and shorter mirrors, EF-S (Short back focus) mount lenses are not physically compatible with full frame Canon EOS bodies or the original EOS D30, D60, or 10D bodies, mounting together should not be attempted as it may damage equipment.