Comparison of Pentax SMC P-FA 20-35mm f/4 AL and Tamron AF 19-35mm f/3.5-4.5

Attribute	Tamron AF 19-35mm f/3.5-4.5 ×	Pentax SMC P-FA 20-35mm f/4 AL ×
Diagonal Angle of View (degree)	63.00 - 97.00	64.00 - 94.00
Zoom System	Rotary	Rotary
Filter Size (mm)	77	58
Aperture (f)	3.50 - 22.00	4.00 - 22.00
Type	Wide Zoom	Wide Zoom
Magnification Ratio (x)	0.08	0.06
APS Equivalent	1.5x: 28.5 - 52.5mm; 1.6x: 30.4 - 56mm	30 - 52.5mm
Diaphragm Blades	8	-
Image Circle	35mm	35mm
Focal Length (mm)	19.00 - 35.00	20.00 - 35.00
Brand	Tamron	Pentax
Name	Tamron AF 19-35mm f/3.5-4.5	Pentax SMC P-FA 20-35mm f/4 AL
Weight (g)	317	245
Diameter (mm)	83.2	69.5
Lens Construction	13 elements in 11 groups	10 elements in 8 groups, including 2 aspherical elements
Focus Details	Internal	-
Length (mm)	67.7	68
Notes	Available AF Mounts: Canon, Minolta, Nikon	-
Closest Focus (m)	0.5	0.3