Comparison of Pentax 40mm f/2.8 Limited HD DA and Pentax 50mm ƒ/1.8 SMC DA

Attribute	Pentax 50mm ƒ/1.8 SMC DA ×	Pentax 40mm f/2.8 Limited HD DA ×
Magnification Ratio (x)	0.15	0.13
Filter Size (mm)	52	49
Focus Details	Quick-shift Focus System for instant switching from auto to manual focus	"Quick Shift" AF/MF mechanism
Closest Focus (m)	0.45	0.4
Lens Construction	6 elements in 5 groups; Front surface has SP (Super Protect) coating	5 elements in 4 groups
Length (mm)	38.5	15
Focal Length (mm)	50.00	40.00
Diaphragm Blades Type	rounded	rounded
Brand	Pentax	Pentax
Image Circle	APS-C	APS-C
Name	Pentax 50mm ƒ/1.8 SMC DA	Pentax 40mm f/2.8 Limited HD DA
Weight (g)	122	89
Type	Tele Prime	Standard Prime
Notes	-	Available in black or silver; High-grade multi-layer HD (High Definition) coating; Rounder aperture blades should yield more pleasing bokeh.
APS Equivalent	76.5mm	61mm
Aperture (f)	1.80 - 22.00	2.80 - 22.00
Diaphragm Blades	7	9
Diagonal Angle of View (degree)	31.50	39.00
Diameter (mm)	63	63