Comparison of Canon EF 17-40mm f/4L USM and Tamron 17-35mm f/2.8-4 Di OSD (Model A037)

Attribute	Canon EF 17-40mm f/4L USM ×	Tamron 17-35mm f/2.8-4 Di OSD (Model A037) ×
Filter Size (mm)	77	77
Notes	Dust and moisture resistant	Available mounts: Canon EF, Nikon F; Moisture-resistant construction; Includes petal type lens hood.
Closest Focus (m)	0.28	0.28
Magnification Ratio (x)	0.24	0.2
Diaphragm Blades Type	-	circular
Type	Wide Zoom	Wide Zoom
APS Equivalent	27 - 64mm	-
Zoom System	Rotary	Rotary
Image Circle	35mm	Image Circle
Focal Length (mm)	17.00 - 40.00	17.00 - 35.00
Brand	Canon	Tamron
Name	Canon EF 17-40mm f/4L USM	Tamron 17-35mm f/2.8-4 Di OSD (Model A037)
Weight (g)	500	459
Aperture (f)	4.00 - 22.00	2.80 - 22.00
Diaphragm Blades	7	7
Diagonal Angle of View (degree)	57.50 - 104.00	63.40 - 103.70
Lens Construction	12 elements in 9 groups, including 3 aspherical elements and 1 S-UD element	15 elements in 10 groups, including 4 LD (Low Dispersion) and 2 GM (Glass Molded) aspherical elements BBAR (Broad-Band Anti-Reflection) coating
Diameter (mm)	83.5	83.2
Length (mm)	96.8	91.4
35mm Equivalent	-	1.5x: 25.5 - 52.5mm; 1.6x: 27.2 - 56mm
Focus Details	Inner focusing; full-time manual focus and USM;	Internal via OSD (Optimized Silent Drive); AF/MF switch