Comparison of Sigma 28-70mm f/2.8 EX DG and Tamron SP AF 28-75mm f/2.8 XR Di LD Aspherical IF

Attribute	Sigma 28-70mm f/2.8 EX DG ×	Tamron SP AF 28-75mm f/2.8 XR Di LD Aspherical IF ×
Notes	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax	Available mounts: Canon, Minolta-D, Nikon-D, Pentax; Includes petal type lens hood.
Aperture (f)	2.80 - 22.00	2.80 - 32.00
Magnification Ratio (x)	0.23	0.26
Filter Size (mm)	67	67
Type	Standard Zoom	Standard Zoom
Closest Focus (m)	0.33	0.33
APS Equivalent	1.5x: 42 - 105mm; 1.6x: 44.8 - 112mm	1.5x: 42 - 112.5mm; 1.6x: 44.8 - 120mm
Diameter (mm)	74	73
Image Circle	35mm	Image Circle
Focal Length (mm)	28.00 - 70.00	28.00 - 75.00
Brand	Sigma	Tamron
Name	Sigma 28-70mm f/2.8 EX DG	Tamron SP AF 28-75mm f/2.8 XR Di LD Aspherical IF
Weight (g)	510	510
Diagonal Angle of View (degree)	34.30 - 75.40	32.00 - 75.00
Diaphragm Blades	9	7
Zoom System	Rotary with lock	Rotary, telescoping
Length (mm)	87.2	92
Focus Details	-	Internal
Lens Construction	14 elements in 12 groups, including 4 aspherical and 2 SLD elements	16 elements in 14 groups, including one Extra Refractive Index element, four Aspherical elements and three Low Dispersion elements