Canon 17-40mm f4.0L USM is an Auto Focus (AF)
Wideangle Zoom lens with 35mm FF max sensor coverage and it is designed to be used with Canon EF mount cameras.
Lens Mount
Canon 17-40mm f4.0L USM is compatible with cameras that have Canon EF lens mount.Some of the latest released cameras with Canon EF lens mount are
Canon 1D X III,
Canon 6D MII and
Canon 5D MIV.
Sensor Coverage
Max sensor coverage of Canon 17-40mm f4.0L USM is 35mm FF.
Focal Range
Canon 17-40mm f4.0L USM has a focal range of 17-40mm and 2.4X zoom ratio. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 27.2 - 64mm.
Optical Image Stabilization
Canon 17-40mm f4.0L USM doesn't have an optical image stabilization system so the only option to stabilize the image taken with this lens is to mount on a camera body with IBIS (sensor based In-body image stabilization).
Body Colour
Canon 17-40mm f4.0L USM is available in Black color.
Zoom Method
Canon 17-40mm f4.0L USM features Rotary (internal) zoom method where the length of the lens doesn't change while you are zooming in or out. Even though this design has a size disadvantage in general compare to extending designs, it has the benefits of better sealing against dust and moisture, no zoom creep and no weight balance shift while zooming.
Aperture
Canon 17-40mm f4.0L USM is a fixed aperture lens with a constant max aperture of f4 from 17mm all the way to the 40mm .
Optical Formula
Canon 17-40mm f4.0L USM's optical formula consists of 12 elements in 9 groups.