Comparison of Nikon 800mm f/5.6E FL ED AF-S VR Nikkor and Pentax SMC P-FA 250-600mm f/5.6 ED IF

Attribute	Nikon 800mm f/5.6E FL ED AF-S VR Nikkor ×	Pentax SMC P-FA 250-600mm f/5.6 ED IF ×
Magnification Ratio (x)	0.151	0.2
Filter Size (mm)	52	43
Focus Details	Internal; Silent Wave Motor; A/M, M/A, M switch; Memory Recall switch	Internal
Closest Focus (m)	5.9	3.5
Lens Construction	20 elements in 13 groups, including 2 ED glass elements, 2 fluorite elements and Nano Crystal Coat	18 elements in 16 groups, including 1 ED element
Length (mm)	461	442
Focal Length (mm)	800.00	250.00 - 600.00
Diagonal Angle of View (degree)	3.20	4.10 - 9.90
Brand	Nikon	Pentax
Image Circle	35mm	35mm
Name	Nikon 800mm f/5.6E FL ED AF-S VR Nikkor	Pentax SMC P-FA 250-600mm f/5.6 ED IF
Weight (g)	4600	5049
Type	Telephoto Prime	Telephoto Zoom
Notes	VR Image Stabilization (up to 4 stops)	-
APS Equivalent	1200mm	375 - 900mm
Aperture (f)	5.60 - 32.00	5.60 - 32.00
Diaphragm Blades	9	-
Zoom System	n/a	Rotary with lock
Diameter (mm)	160	71