Comparison of Pentax 18-270mm f/3.5-6.3 ED SDM SMC DA and Sigma 28-300mm f/3.5-6.3 DG Macro

Attribute	Sigma 28-300mm f/3.5-6.3 DG Macro ×	Pentax 18-270mm f/3.5-6.3 ED SDM SMC DA ×
Notes	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax	Autofocus supported on K10D and later bodies. Optional Accessories: PH-RBD lens hood, S80-120 case.
Magnification Ratio (x)	0.33	0.26
Filter Size (mm)	62	62
Length (mm)	88	89
Closest Focus (m)	0.5	0.45
Diagonal Angle of View (degree)	8.20 - 75.40	6.00 - 76.00
Focus Details	Internal	Internal with supersonic AF motor (SDM)
Focal Length (mm)	28.00 - 300.00	18.00 - 270.00
APS Equivalent	1.5x: 42 - 450mm; 1.6x: 44.8 - 480mm	27.5 - 414mm
Brand	Sigma	Pentax
Image Circle	35mm	APS-C
Name	Sigma 28-300mm f/3.5-6.3 DG Macro	Pentax 18-270mm f/3.5-6.3 ED SDM SMC DA
Weight (g)	490	453
Type	Standard Zoom	Standard Zoom
Aperture (f)	3.50 - 22.00	3.50 - 45.00
Diaphragm Blades	8	7
Diaphragm Blades Type	-	rounded
Lens Construction	15 elements in 13 groups, including 4 aspherical and 2 SLD elements	16 elements in 13 groups, including 2 ED and 2 aspherical elements
Zoom System	Rotary with lock	Rotary, with lock switch
Diameter (mm)	74	75.8