Comparison of Canon EF 400mm f/2.8L IS USM and Tamron SP AF 300mm f/2.8 LD IF

Attribute	Canon EF 400mm f/2.8L IS USM ×	Tamron SP AF 300mm f/2.8 LD IF ×
Aperture (f)	2.80 - 32.00	2.80 - 32.00
Filter Size (mm)	52	43
Notes	Image Stabilization	Available AF Mounts: Canon, Minolta, Nikon; Included Accessories: Lens Hood, Case
Closest Focus (m)	3	2.5
Magnification Ratio (x)	0.15	0.141
Type	Telephoto Prime	Telephoto Prime
Focus Details	Inner focusing; full-time manual focus and USM	Internal; Focus ring slides back and forth to switch between AF and MF
APS Equivalent	640mm	1.5x: 450mm; 1.6x: 480mm
Diaphragm Blades	8	9
Image Circle	35mm	35mm
Focal Length (mm)	400.00	300.00
Brand	Canon	Tamron
Name	Canon EF 400mm f/2.8L IS USM	Tamron SP AF 300mm f/2.8 LD IF
Weight (g)	5370	2800
Diagonal Angle of View (degree)	6.20	8.00
Length (mm)	349	215.9
Diameter (mm)	163	120
Lens Construction	17 elements in 13 groups, including 1 flourite and 2 UD elements	10 elements in 7 groups, including 2 LD elements