The optical performance, fast f/2.8 speed and ultra-wide-angle coverage make this a great choice for many applications, like interiors, scenics, travel and photojournalism.
It uses a “floating” optical system for excellent sharpness even at its minimum focusing distance of under 10 inches (0.25m), and with a ring-type USM and full-time manual focusing capability, offers the speed and handling pros expect.

Weight (g):	405
Filter Diameter (mm):	72
Maximum Magnification (x):	0.14
Magnification with Extension Tube EF12:	0.72-0.60
Diagonal Angle of View:	94°
Horizontal angle of view:	84°
Lens Construction (elements/groups):	11/9
Max. Diameter x Length (mm):	77.5x70.6
Minimum Aperture:	22
No. of Diaphragm blades:	5
Closest Focusing Distance (m):	0.25
AF Actuator:	USM (Mechanical full-time manual focusing built-in.)
Hard Case:	LH-D13
Lens Hood:	EW-75
float:	float
ir:	ir
ultrasonic:	ultrasonic
ftm:	ftm
All data based on Canon's Standard Test Method:
Subject to change without notice: Ultra wide focal length, suitable for many applications Lightweight (405g) and compact design High level performance with floating rear focusing system Ultrasonic motor (USM) for fast and near silent AF Ultra-Wide & Wide Lenses Ultra-wide-angle lens for serious applications. Easy to hold and carry at 405g. Floating rear focusing system. Sharp images are obtained at all subject distances.