Comparison of Sigma 18-50mm ƒ/2.8-4.5 DC OS HSM and Tamron SP AF 17-50mm f/2.8 XR Di II LD Aspherical IF

Attribute	Sigma 18-50mm ƒ/2.8-4.5 DC OS HSM ×	Tamron SP AF 17-50mm f/2.8 XR Di II LD Aspherical IF ×
Filter Size (mm)	67	67
Notes	Available AF Mounts: Sigma, Canon, Nikon, Sony, Pentax. Included Accessories: Case, Lens Hood. Optical Stabilization.	Available AF mounts: Canon, Konica Minolta, Nikon, Pentax; Includes petal type lens hood.
Closest Focus (m)	0.3	0.27
Magnification Ratio (x)	0.24	0.22
Type	Standard Zoom	Standard Zoom
Length (mm)	88.6	81.7
APS Equivalent	1.5x: 27 - 75mm; 1.6x: 28.8 - 80mm	1.5x: 25.5 - 75mm; 1.6x: 27.2 - 80mm
Zoom System	Rotary	Rotary
Image Circle	Image Circle	Image Circle
Focal Length (mm)	18.00 - 50.00	17.00 - 50.00
Brand	Sigma	Tamron
Name	Sigma 18-50mm ƒ/2.8-4.5 DC OS HSM	Tamron SP AF 17-50mm f/2.8 XR Di II LD Aspherical IF
Weight (g)	395	398
Aperture (f)	2.80 - 22.00	2.80 - 32.00
Diaphragm Blades	7	7
Diagonal Angle of View (degree)	27.90 - 69.30	31.20 - 78.80
Lens Construction	16 elements in 12 groups, including 2 SLD and 3 aspherical lenses	16 elements in 13 groups, including Low Dispersion and Aspherical elements
Diameter (mm)	74	74
Focus Details	Internal with HSM	Internal