Comparison of Sigma 28-70mm f/2.8-4 and Tamron AF 28-80mm f/3.5-5.6 Aspherical

Attribute	Sigma 28-70mm f/2.8-4 ×	Tamron AF 28-80mm f/3.5-5.6 Aspherical ×
Magnification Ratio (x)	0.15	0.13
Filter Size (mm)	62	58
Front Element Rotation	-	-
Closest Focus (m)	0.5	0.7
Lens Construction	11 elements in 8 groups, including 1 aspherical element	7 elements in 7 groups
Length (mm)	60	70.4
Focal Length (mm)	28.00 - 70.00	28.00 - 80.00
Diagonal Angle of View (degree)	34.30 - 75.40	30.00 - 75.00
Brand	Sigma	Tamron
Image Circle	35mm	35mm
Name	Sigma 28-70mm f/2.8-4	Tamron AF 28-80mm f/3.5-5.6 Aspherical
Weight (g)	245	237
Type	Standard Zoom	Standard Zoom
Notes	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax; Included Accessories: Lens Hood	Available AF Mounts: Canon, Minolta, Nikon; Included Accessories: Lens Hood
APS Equivalent	1.5x: 42 - 105mm; 1.6x: 44.8 - 112mm	1.5x: 42 - 120mm; 1.6x: 44.8 - 128mm
Aperture (f)	2.80 - 22.00	3.50 - 22.00
Diaphragm Blades	8	6
Zoom System	Rotary	Rotary
Diameter (mm)	67.5	72