Comparison of Canon Extender EF 2x III and Tamron 2X TC-X20

Attribute	Tamron 2X TC-X20 ×	Canon Extender EF 2x III ×
Notes	Available AF Mounts: Canon EF, Nikon F; Included Accessories: Mount cap, Rear cap, Lens case	-
Weight (g)	360	325
Type	Teleconverter	Teleconverter
Brand	Tamron	Canon
Name	Tamron 2X TC-X20	Canon Extender EF 2x III
Lens Construction	9 elements in 5 groups, including 1 Low Dispersion element	9 elements in 5 groups
Image Circle	35mm	35mm
Magnification Ratio (x)	2	2
Diameter (mm)	69.8	72
Focal Length Multiplier	2X that of the master lens	2X that of the master lens
Effective Reduction in Aperture	2 f-stops	2 f-stops
Length (mm)	53.6	52.7