Comparison of Nikon 20mm f/2.8 AIS Nikkor and Pentax 15mm ƒ/4 ED AL Limited SMC DA

Attribute	Nikon 20mm f/2.8 AIS Nikkor ×	Pentax 15mm ƒ/4 ED AL Limited SMC DA ×
Aperture (f)	2.80 - 22.00	4.00 - 22.00
Filter Size (mm)	62	49
Notes	Classic Nikon F Mount; AIS / AI / NAI Metering Compatibility; Includes front and rear lens caps.	Hood is built-in, pullout type
Closest Focus (m)	0.25	0.18
Magnification Ratio (x)	0.12	0.15
Type	Wide Prime	Wide Prime
Focus Details	Manual Focus Only; Close Range Correction	Internal, with "Quick-Shift" focus system
APS Equivalent	30mm	23mm
Diaphragm Blades	7	7
Image Circle	35mm (FX)	APS-C
Focal Length (mm)	20.00	15.00
Brand	Nikon	Pentax
Name	Nikon 20mm f/2.8 AIS Nikkor	Pentax 15mm ƒ/4 ED AL Limited SMC DA
Weight (g)	260	212
Diagonal Angle of View (degree)	94.00	86.00
Length (mm)	43	39.5
Diameter (mm)	66	63
Lens Construction	12 elements in 9 groups	8 elements in 6 groups