Comparison of Sigma 17-35mm f/2.8-4 EX DG Aspherical HSM and Tokina 20-35mm f/2.8 AT-X 235 AF PRO

Attribute	Sigma 17-35mm f/2.8-4 EX DG Aspherical HSM ×	Tokina 20-35mm f/2.8 AT-X 235 AF PRO ×
Magnification Ratio (x)	0.22	-
Filter Size (mm)	77	77
Focus Details	Internal Focus; HSM with full-time manual override	Internal with One-Touch Focus Clutch mechanism
Closest Focus (m)	0.27	0.25
Lens Construction	16 elements in 13 groups, including 2 aspherical and 1 SLD elements	15 elements in 11 groups, including 2 aspherical elements
Length (mm)	88.7	85.5
Focal Length (mm)	17.00 - 35.00	20.00 - 35.00
Diagonal Angle of View (degree)	63.40 - 103.70	63.20 - 93.60
Brand	Sigma	Tokina
Image Circle	35mm	35mm
Name	Sigma 17-35mm f/2.8-4 EX DG Aspherical HSM	Tokina 20-35mm f/2.8 AT-X 235 AF PRO
Weight (g)	560	585
Type	Wide Zoom	Wide Zoom
Notes	Available AF Mounts: [HSM version]: Sigma, Canon, Nikon; [w/o HSM]: Minolta, Pentax	Available AF Mounts: Canon, Minolta, Nikon; Included Accessories: Lens Hood, Fitted Soft Case
APS Equivalent	1.5x: 25.5 - 52.5mm; 1.6x: 27.2 - 56mm	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)	83.5	84