Canon EF 17-40mm lens

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EF 17–40mm f/4L USM

Maker	Canon
Technical data
Type	Zoom
Focus drive	Ultrasonic motor
Focal length	17–40mm
Crop factor	1.0
Aperture (max/min)	f/4–f/22
Close focus distance	280mm / 11in
Max. magnification	0.24 (at 40mm)
Diaphragm blades	7
Construction	12 elements in 9 groups
Features
Short back focus	No
Lens-based stabilization	No
Macro capable	No
Application	Ultra-Wide Zoom
Physical
Max. length	96.8mm / 3.8in
Diameter	83.5mm / 3.3in
Weight	475g / 1.1lbs
Filter diameter	77mm
Accessories
Lens hood	EW-83E, EW-83H, EW-83J
Case	LP1319
Angle of view
Horizontal	93°–49°20'
Vertical	70°30'–34°
Diagonal	104°–57°30'
History
Introduction	2003
Retail info
MSRP	$800 USD

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. It is one of the few Canon photo lenses that are parfocal.^[1]