Comparison of Sigma 17-70mm ƒ/2.8-4 DC Macro OS HSM Contemporary and Sigma 18-50mm ƒ/2.8 EX DC Macro

Attribute	Sigma 17-70mm ƒ/2.8-4 DC Macro OS HSM Contemporary ×	Sigma 18-50mm ƒ/2.8 EX DC Macro ×
Notes	Image Stabilized (up to 4 stops); Available AF Mounts: Canon, Nikon, Sigma, Pentax, Sony; Accessory: lens hood LH780-03.	Available AF Mounts: Sigma, Canon, Nikon, Sony, Pentax, Four-Thirds
Magnification Ratio (x)	0.34	0.33
Filter Size (mm)	72	72
Length (mm)	82	85.8
Closest Focus (m)	0.22	0.2
Diagonal Angle of View (degree)	22.90 - 79.70	27.90 - 69.30
Focus Details	Internal, with Hyper-Sonic Motor; AF/MF switch	Internal focusing system
Focal Length (mm)	17.00 - 70.00	18.00 - 50.00
APS Equivalent	1.5x: 25.5 - 105mm; 1.6x: 27.2 - 112mm	1.5x: 27 - 75mm; 1.6x: 28.8 - 80mm
Brand	Sigma	Sigma
Image Circle	APS-C	Image Circle
Name	Sigma 17-70mm ƒ/2.8-4 DC Macro OS HSM Contemporary	Sigma 18-50mm ƒ/2.8 EX DC Macro
Weight (g)	470	450
Type	Standard Zoom	Standard Zoom
Aperture (f)	2.80 - 22.00	2.80 - 22.00
Diaphragm Blades	7	7
Diaphragm Blades Type	rounded	-
Lens Construction	16 elements in 14 groups, including FLD, SLD, and 3 aspherical elements	15 elements in 13 groups, including aspherical and Special Low Dispersion (SLD) elementss
Zoom System	Rotary with lock	Rotary, non-telescoping
Diameter (mm)	79	79