Canon EF 17–40mm f/4L USM is a wide-angle zoom with constant f/4 aperture and fast autofocus, suitable for landscapes, architecture, and interior photography with reduced edge distortion. On APS-C cameras it provides an equivalent range of 28–70mm. The lens uses three aspherical elements and UD glass to control distortion and chromatic aberration. Advanced coatings reduce flare and ghosting. Minimum focusing distance is 0.28 m across the zoom range. A circular diaphragm produces smooth out-of-focus rendering, and an additional aperture helps improve contrast. Best suited for well-lit environments due to its moderate aperture. Included: Canon EF 17–40mm f/4L USM lens, front and rear caps, hood, 77 mm UV filter, pouch.