Canon 1.4x EF Extender II (Teleconverter).
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. When combined with pro level EOS cameras & EF supertelephoto lenses with image stabilization, near imperviousness to weather extremes is achieved thanks to rubber gasket seals. Improved anti-reflective internal coatings also increase transmissivity & performance in backlit conditions.
The extender will cut back the amount of light by one f/stop. For example using a 1.4x teleconverter with a 300mm f/2.8 lens will effectively increase the focal length to approximately 420mm and the f/2.8 aperture will now be f/4. Teleconverters are best used with longer telephoto lenses and are not recommended for lenses wider than 50mm, e.g. 28-105mm (35mm format).
Notes on Camera Compatibility (compatibility chart):
- Autofocus is possible on any EOS camera when combined with a lens having an f/4 or faster maximum aperture.
- If the lens is attached to an EOS camera having multiple focusing points and an extender attached, only the center focusing point will be usable for AF.
- When attached to the EF 180mm f/3.5L Macro USM lens, the autofocusing range is from 2.6' (0.8 m) to infinity. It varies slightly with the EOS-1v, EOS-1N, EOS-1 and EOS-3.
- When attached to the EF 400mm f/4L DO ISM lens or the EF 100-400 f/4.5-5.6 lens, autofocus is possible with the center focus point only with EOS 1Ds Mark II, EOS 1Ds Mark III, EOS 1D Mark II, EOS 1D Mark III, EOS 1D, EOS 1v and EOS 3.
- When attached to the EF 800mm f/5.6L IS USM autofocus is possible with the center focus point only with EOS 1Ds Mark II, EOS 1Ds, EOS 1D Mark II N, EOS 1D Mark II, EOS 1v HS and EOS 3.
- When attached to the EF 100-400mm f/4.5-5.6L IS USM lens, the Image Stabilizer (IS) will not work with the following EOS cameras: 650, 630, 620, 600, RT, 700, 750, 850, 1, A2, A3, 10S, Elan, Rebel, Rebel II, Rebel S and Rebel SII.