The EF 2x II doubles the focal length of any lens it's mounted to, and reduces its effective aperture by two stops. The effective aperture of the lens is increased by one or two stops respectively. Autofocusing does not operate if the effective maximum aperture is greater than f/5.6 (greater than f/8 on the EOS 1V and EOS 3).

A totally new 7-element optical design for this version II extender means superior image quality combined with a doubling of the lenss marked focal length (with a two-stop reduction in effective aperture). Compatible with the same lenses as the 1.4x II extender, the EF 2x II still allows autofocus with any EOS body when used with a lens f/2.8 or faster. It shares the improved anti-reflection internal design and weather-resistant exterior, including seals at its front and rear lens mounts matching those on Canons newest professional lenses and camera bodies.

• Dust and moisture resistant construction
• Extends the master lens focal length by 2.0x
• Minimum loss of lens performance
• Reduces inner reflection for higher image quality