Comparison of Canon EF-S 17-55mm f/2.8 IS USM and Sigma 17-50mm ƒ/2.8 EX DC OS HSM

Attribute	Canon EF-S 17-55mm f/2.8 IS USM ×	Sigma 17-50mm ƒ/2.8 EX DC OS HSM ×
Aperture (f)	2.80 - 22.00	2.80 - 22.00
Filter Size (mm)	77	77
Notes	Image Stabilization; Included Accessories: Lens Hood EW-83J	Image Stabilized (except for Pentax and Sony mounts). Available AF Mounts: Canon, Nikon, Pentax, Sigma, Sony. Included Accessories: Case, Petal-type
Closest Focus (m)	0.35	0.28
Magnification Ratio (x)	0.17	0.2
Diameter (mm)	83.5	83.5
Type	Standard Zoom	Standard Zoom
APS Equivalent	27 - 88mm	1.5x: 26 - 75mm; 1.6x: 27 - 80mm
Diaphragm Blades	7	7
Image Circle	APS-C	APS-C
Focal Length (mm)	17.00 - 55.00	17.00 - 50.00
Brand	Canon	Sigma
Name	Canon EF-S 17-55mm f/2.8 IS USM	Sigma 17-50mm ƒ/2.8 EX DC OS HSM
Weight (g)	645	565
Diagonal Angle of View (degree)	27.80 - 78.50	27.90 - 72.40
Lens Construction	19 elements in 12 groups	17 elements in 13 groups, including 2 FLD glass elements
Zoom System	Rotary	Rotary with lock
Length (mm)	110.6	91.8
Diaphragm Blades Type	-	rounded
Focus Details	USM with full-time manual focusing	Internal, with Hyper-Sonic Motor; AF/MF switch