Comparison of Pentax SMC P-FA 28-105mm f/3.2-4.5 AL IF and Sigma 28-105mm f/3.8-5.6 UC-III Aspherical IF

Attribute	Sigma 28-105mm f/3.8-5.6 UC-III Aspherical IF ×	Pentax SMC P-FA 28-105mm f/3.2-4.5 AL IF ×
Notes	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax	Also available in Silver
Aperture (f)	3.80 - 22.00	3.20 - 32.00
Magnification Ratio (x)	0.18	0.19
Filter Size (mm)	62	58
Type	Standard Zoom	Standard Zoom
Closest Focus (m)	0.5	0.5
APS Equivalent	1.5x: 42 - 157.5mm; 1.6x: 44.8 - 168mm	42 - 157.5mm
Diameter (mm)	71	66
Image Circle	35mm	35mm
Focal Length (mm)	28.00 - 105.00	28.00 - 105.00
Brand	Sigma	Pentax
Name	Sigma 28-105mm f/3.8-5.6 UC-III Aspherical IF	Pentax SMC P-FA 28-105mm f/3.2-4.5 AL IF
Weight (g)	275	255
Diagonal Angle of View (degree)	23.30 - 75.40	23.50 - 75.00
Lens Construction	13 elements in 12 groups, including 1 aspherical element	12 elements in 11 groups
Zoom System	Rotary	Rotary
Length (mm)	72.5	66
Diaphragm Blades	7	-
Focus Details	Internal	Internal