Comparison of Sigma 20-40mm f/2.8 EX DG Aspherical and Tokina 20-35mm f/2.8 AT-X 235 AF PRO

Attribute	Sigma 20-40mm f/2.8 EX DG Aspherical ×	Tokina 20-35mm f/2.8 AT-X 235 AF PRO ×
Magnification Ratio (x)	0.22	-
Filter Size (mm)	82	77
Focus Details	Internal with Dual Focus mechanism	Internal with One-Touch Focus Clutch mechanism
Closest Focus (m)	0.27	0.25
Lens Construction	17 elements in 13 groups, including 2 aspherical elements	15 elements in 11 groups, including 2 aspherical elements
Length (mm)	107.8	85.5
Focal Length (mm)	20.00 - 40.00	20.00 - 35.00
Diagonal Angle of View (degree)	56.80 - 94.50	63.20 - 93.60
Brand	Sigma	Tokina
Image Circle	35mm	35mm
Name	Sigma 20-40mm f/2.8 EX DG Aspherical	Tokina 20-35mm f/2.8 AT-X 235 AF PRO
Weight (g)	595	585
Type	Wide Zoom	Wide Zoom
Notes	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax	Available AF Mounts: Canon, Minolta, Nikon; Included Accessories: Lens Hood, Fitted Soft Case
APS Equivalent	1.5x: 30 - 60mm; 1.6x: 32 - 64mm	1.5x: 30 - 52.5mm; 1.6x: 32 - 56mm
Aperture (f)	2.80 - 22.00	2.80 - 22.00
Diaphragm Blades	8	8
Zoom System	Rotary	Rotary
Diameter (mm)	89	84