Comparison of Canon EF 28mm f/2.8 and Pentax SMC P-DA 21mm f/3.2 AL Limited

Attribute	Canon EF 28mm f/2.8 ×	Pentax SMC P-DA 21mm f/3.2 AL Limited ×
Diagonal Angle of View (degree)	75.00	68.00
Filter Size (mm)	52	43
Aperture (f)	2.80 - 22.00	3.20 - 22.00
Closest Focus (m)	0.3	0.2
Magnification Ratio (x)	0.13	0.17
Type	Wide Prime	Wide Prime
Focus Details	Focus Details	"Quick Shift" AF/MF mechanism
APS Equivalent	45mm	31.5mm
Diaphragm Blades	5	7
Image Circle	35mm	APS-C
Focal Length (mm)	28.00	21.00
Brand	Canon	Pentax
Name	Canon EF 28mm f/2.8	Pentax SMC P-DA 21mm f/3.2 AL Limited
Weight (g)	185	140
Diameter (mm)	67	63
Length (mm)	42	25
Notes	-	Dual filter attachment design: 43mm filters on the hood, and 49mm filters on the lens (without use of the hood).
Lens Construction	5 elements in 5 groups, including 1 aspherical element	8 elements in 5 groups, including 1 hybrid aspherical element