Comparison of Canon EF 16-35mm f/2.8L II USM and Sigma 20-40mm f/2.8 EX DG Aspherical

Attribute	Canon EF 16-35mm f/2.8L II USM ×	Sigma 20-40mm f/2.8 EX DG Aspherical ×
Filter Size (mm)	82	82
Notes	Includes Hood, Lens Case	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax
Closest Focus (m)	0.28	0.27
Magnification Ratio (x)	0.22	0.22
Type	Wide Zoom	Wide Zoom
Length (mm)	111.6	107.8
APS Equivalent	26 - 56mm	1.5x: 30 - 60mm; 1.6x: 32 - 64mm
Zoom System	Rotary	Rotary
Image Circle	35mm	35mm
Focal Length (mm)	16.00 - 35.00	20.00 - 40.00
Brand	Canon	Sigma
Name	Canon EF 16-35mm f/2.8L II USM	Sigma 20-40mm f/2.8 EX DG Aspherical
Weight (g)	635	595
Aperture (f)	2.80 - 22.00	2.80 - 22.00
Diaphragm Blades	7	8
Diagonal Angle of View (degree)	63.00 - 108.20	56.80 - 94.50
Lens Construction	16 elements in 12 groups, including 3 aspherical and 2 UD elements	17 elements in 13 groups, including 2 aspherical elements
Diameter (mm)	88.5	89
Focus Details	Inner focusing; full-time manual focus and USM	Internal with Dual Focus mechanism