The Canon EF 1.4x II Extender is a high-quality teleconverter that preserves the image quality of the lens it's mounted to and multiplies its focal length by 1.4x.

The 1.4x extender (also known as a teleconverter) will multiply the focal length of the existing lens by 1.4x, and will cut back the amount of light by one f/stop. For example, using a 1.4x teleconverter with a 300mm lens will effectively increase the focal length to approximately 420mm. A lens set to f/2.8 will become f/4.

This extender is only compatible with the following lenses:

• EF 135mm f/2L USM
• EF 180mm f/3.5L Macro USM
• EF 200mm f/1.8L USM
• EF 200mm f/2.8L II USM
• EF 300mm f/2.8L IS USM
• EF 300mm f/4L IS USM
• EF 400mm f/2.8L IS USM
• EF 400mm f/4L DO IS USM
• EF 400mm f/5.6L USM
• EF 500mm f/4L IS USM
• EF 600mm f/4L IS USM
• EF 1200mm f/5.6L USM
• EF 70-200mm f/2.8L USM

Note: Autofocus will work only if the effective aperture is within the range of the camera (currently f/8 with most EOS cameras).