Comparison of Pentax 17-70mm ƒ/4 AL IF SDM SMC DA and Tamron 17-70mm F/2.8 Di III-A VC RXD (Model B070)

Attribute	Pentax 17-70mm ƒ/4 AL IF SDM SMC DA ×	Tamron 17-70mm F/2.8 Di III-A VC RXD (Model B070) ×
Filter Size (mm)	67	67
Notes	Included Accessories: Lens Hood	Available mounts: Sony E-mount; Moisture-resisteant construction
Closest Focus (m)	0.28	0.19
Magnification Ratio (x)	0.31	0.21
Diaphragm Blades Type	-	circular
Type	Standard Zoom	Wide Zoom
APS Equivalent	25.5 - 105mm	-
Zoom System	Rotary	Rotary
Image Circle	APS-C	Image Circle
Focal Length (mm)	17.00 - 70.00	17.00 - 70.00
Brand	Pentax	Tamron
Name	Pentax 17-70mm ƒ/4 AL IF SDM SMC DA	Tamron 17-70mm F/2.8 Di III-A VC RXD (Model B070)
Weight (g)	485	525
Aperture (f)	4.00 - 22.00	2.80 - 22.00
Diaphragm Blades	7	9
Diagonal Angle of View (degree)	23.00 - 79.00	23.00 - 79.90
Lens Construction	17 elements in 12 groups	16 elements in 12 groups, including 2 LD (Low Dispersion) and 3 aspherical elements (2 molded glass aspherical elements, one hybrid aspherical elemen
Diameter (mm)	75	74.6
Length (mm)	93.5	119.3
35mm Equivalent	-	25.5-105mm
Focus Details	Internal; SDM with Quick-shift Focus System	Internal via RXD (Rapid eXtra-silent stepping Drive) with DMF (Direct Manual Focus)