Multiply the focal length of your 135mm or longer lens by 1.4x without sacrificing image quality with the Canon EF 1.4x II extender. Optically superb, the lens fits all Canon 135mm fixed focal length lenses (except the 135mm f/2.8 Softfocus lens), along with the EF 70-200mm f/2.8L, 70-200mm f/2.8L, 70-200mm f/4.0L, 70-200mm f/4.0L IS USM, and 100-400mm f/4.5-5.6L IS zoom lenses. In addition, the extender doesn't sacrifice your autofocus on any EOS camera as long as it's combined with a lens having an f/4 or faster maximum aperture (the extender reduces the effective aperture by one f-stop). Best of all, this version maintains the outstanding optics of the earlier incarnation, but adds a weather-resistant construction and improved anti-reflective surfaces in the barrel. The EF 1.4x II extender, which measures 2.9 inches in diameter and 1.1 inches long, weighs 7.8 ounces.
The Canon 1.4x (L) Teleconverter EF is for use on Canon EF 'L' series lenses ONLY. It will NOT work with standard Canon EF non-L lenses.
Made of Canon's extra sharp Fluorite glass, the 1.4x Tele-converter will give a 40% increase in magnification to any lens attached to it, at the cost of only one f-stop of light transmission. A 200mm f/4 lens, for example, becomes a 280mm f/5.6 lens with the 1.4x Tele-converter behind it. No correction is required for either focusing or exposure operations, the camera does it all. (some focusing restrictions exist. please see specifications). As an added bonus, minimum focusing distance, for any lens, remains the same and that can really improve macro performance! Comes complete with case and strap.