Canon EF 17-40mm lens

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Key Features
EF 17-40mm f4/L USM

Maker:	Canon
Image Stabilisation:	No
Silent AF Motor:	Yes
Short Back Focus:	No
Macro Capable:	No
Application:	Ultra-Wide Zoom
Technical Data
Type:	Zoom
Focal Length :	17-40mm
Frame Coverage:	Full Frame
Aperture (max/min):	f/4 - f/22
Construction:	9 groups / 12 elements
# Diaphragm blades:	7
Close focus distance:	11in / 280mm
Physical
Max. Diameter:	3.3in / 83.5mm
Max. Length:	3.8in / 96.8mm
Weight:	1.1lbs / 475g
Filter diameter:	77mm
Accessories
Lens Hood:	EW-83E
Angle of View
Diagonal:	104°-57°30'
History
Introduced:	2003
Retail Info
MSRP US$	$850

The EF 17-40mm f/4L USM lens is a wide-angle lens made by Canon Inc. The lens has an EF mount to work with the EOS line of cameras. Other than the front element, it is sealed against dust and water, and features a diaphragm which remains nearly circular from f/4 to f/8.

While a member of the L lineup, which is primarily aimed at professionals, the 17-40 is primarily aimed at advanced amateurs who want a high-quality lens but are unwilling or unable to pay for the EF 16-35mm f/2.8L USM lens, which costs approximately twice as much as the 17-40mm.

This lens is also a popular step up from the stock kit lens on many of Canon's EOS Digital family of cameras, the EF-S 18-55mm f/3.5-5.6, for those who wish to remain with a wide angle lens. This lens is often paired with an L series telephoto lens, such as the EF 28-300mm f/3.5-5.6 L USM or any of the EF 70-200mm family (f/4L USM, f/4L IS USM, f/2.8L USM, f/2.8L IS USM).