Overview:

Ultra-wide-angle lens for serious applications. Easy to hold and carry at 14.3 oz. (405g). Floating rear focusing system. Sharp images are obtained at all subject distances.

• The EF 20mm f/2.8 USM Lens from Canon is an ultra-wide-angle lens with a fast maximum aperture for full frame EF mount cameras. A floating rear focusing system gives sharp images at all subject distances and an ultrasonic motor (USM) enables fast, smooth and quiet autofocus. Full-time manual focus override allows for precise manual focus even when in AF mode. The minimum focus distance is 9.8".
• Sharp, high-contrast images and minimized aberrations result from the lens' optical construction which includes aspherical and Super UD lens elements. Canon's Super Spectra lens coating suppresses ghosting and flare by absorbing light that might otherwise reflect off the camera's sensor. A metal front barrel- including filter ring and lens hood mount- provides durability and a stable hold for those optional accessories.

Features:

• Ultra-wide-angle lens with diagonal angle of view of 94° for full frame EF mount DSLRs
• Ultrasonic autofocus motor for precise, fast and quiet autofocus.
• Manual Focus Override
• 9.8" minimum focus distance
• Six-blade circular aperture

1.) Mounting and Detaching the Lens- ( see your camera's instructions for details on mounting and detaching the lens)

2.) Setting the Focus Mode - To shoot in autofocus (AF) mode, set the focus mode switch to AF. To shoot in manual focus (MF) mode , set the focus mode switch to MF and focus by turning the focusing ring. The focusing ring always works, regardless of the focus mode.

3.) Infinity Compensation Mark - To compensate for shifting of the infinity focus point that results from changes in temperature.

4.) Autofocus Mode (AF)

5.) Full-time Manual Focus - After autofucosing in ONE SHOT AF mode, focus manually by pressing the shutter button halfway and turning the focusing ring

6.) The infinity position at normal temperature is the point at which the vertical line of the L mark is aligned with the distance indicator on the distance scale

7.) Infrared Index - corrects the focus setting when using monochrome infrared film.Focus on the subject in MF, then adjust the distance setting by moving the focusing ring to the corresponding infrared index mark

8.) Filters - You can attach filters to the filter mounting thread on the front of the lens

9.) Hood - The lens hood can keep unwanted light out of the lens and also protects the lens from rain,snow and dust. To attach the hood, align the hood's attachment position mark with the red dot on the front of the lens then turn the hood in the direction of the arrow until the lens's red dot is aligned with the hood's  stop position mark

10.) Press the buttons on both sides of the hood to attach

11.) Pull the hood out from the front of the lens until it stops

Specifications:

• Focal Length & Maximum Aperture............. 20mm 1:2.8
• Lens Construction.....................11 elements in 9 groups
• Diagonal Angle of View .............94°
• Focus Adjustment........................Rear focusing system with USM
• Closest Focusing Distance...............0.25m / 0.8 ft.
• Filter Size  ...................................... 72mm
• Max. Diameter x Length, Weight........3.1" x 2.8", 14.3 oz. / 77.5 x 70.6mm, 405g