Comparison of Pentax SMC P-FA 31mm f/1.8 AL Limited and Sigma 35mm f/2 DG DN Contemporary

Attribute	Pentax SMC P-FA 31mm f/1.8 AL Limited ×	Sigma 35mm f/2 DG DN Contemporary ×
Diagonal Angle of View (degree)	70.00	63.40
Diameter (mm)	65	70
Filter Size (mm)	58	58
Aperture (f)	1.80 - 22.00	2.00 - 22.00
Type	Wide Prime	Wide Prime
Magnification Ratio (x)	0.16	0.18
APS Equivalent	46.5mm	1.5x: 52.5mm
Notes	-	Available AF Mounts: L-Mount, Sony E-Mount
Image Circle	35mm	35mm
Focal Length (mm)	31.00	35.00
Brand	Pentax	Sigma
Name	Pentax SMC P-FA 31mm f/1.8 AL Limited	Sigma 35mm f/2 DG DN Contemporary
Weight (g)	345	325
Diaphragm Blades	-	9
Lens Construction	9 elements in 7 groups, including 1 aspherical element	10 elements in 9 groups, with 1 SLD glass and 3 aspherical lenses
Focus Details	-	Smooth, quiet and high-speed AF via stepping motor
Length (mm)	68.5	65.4
Diaphragm Blades Type	-	rounded
Closest Focus (m)	0.3	0.27