With a constant f/2.8 aperture throughout the zoom range and a 3-stop Image Stabiliser, the EF-S 17-55mm f/2.8 IS USM provides outstanding performance and framing flexibility in low light conditions
To meet user demands for a fast EF-S zoom lens, Canon has specially designed a new lens with a large aperture of f/2.8 for select Canon Digital SLR cameras.* The large circular aperture produces a shallow depth-of-field, creating background blur that draws attention to the photographic subject. The lens construction includes UD and aspherical elements, which deliver impressive image quality throughout the entire zoom range.