Comparison of Pentax 17-70mm ƒ/4 AL IF SDM SMC DA and Sigma 17-70mm f/2.8-4.5 DC Macro

Attribute	Pentax 17-70mm ƒ/4 AL IF SDM SMC DA ×	Sigma 17-70mm f/2.8-4.5 DC Macro ×
Filter Size (mm)	67	72
Notes	Included Accessories: Lens Hood	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax
Closest Focus (m)	0.28	0.2
Magnification Ratio (x)	0.31	0.43
Type	Standard Zoom	Standard Zoom
Length (mm)	93.5	82.5
APS Equivalent	25.5 - 105mm	1.5x: 25.5 - 105mm; 1.6x: 27.2 - 112mm
Zoom System	Rotary	Rotary with lock
Image Circle	APS-C	APS-C
Focal Length (mm)	17.00 - 70.00	17.00 - 70.00
Brand	Pentax	Sigma
Name	Pentax 17-70mm ƒ/4 AL IF SDM SMC DA	Sigma 17-70mm f/2.8-4.5 DC Macro
Weight (g)	485	455
Aperture (f)	4.00 - 22.00	2.80 - 22.00
Diaphragm Blades	7	7
Diagonal Angle of View (degree)	23.00 - 79.00	20.20 - 72.40
Lens Construction	17 elements in 12 groups	15 elements in 12 groups, including 1 SLD and 2 aspherical elements
Diameter (mm)	75	79
Focus Details	Internal; SDM with Quick-shift Focus System	Internal