Superb optically, it preserves the image quality of the lens it's mounted to and multiplies its focal length 1.4x. Effective aperture is reduced by one f-stop; autofocus is possible on any EOS camera when combined with a lens having an f/4 or faster maximum aperture. The new version II maintains the outstanding optics of the previous version, and adds enhanced weather-resistant construction, and improved anti-reflective surfaces in the barrel.
Note from Canon: This convertor is only compatible with fixed focal length L-series lenses 135mm and over, as well as the EF 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/2.8L IS II, EF 70-200/2.8L IS III, EF 70-200/4L, EF 70-200/4L IS, EF 70-200/4L IS II, EF 100-400/4.5-5.6L, and EF 100-400/4.5-5.6L IS II. Additionally, please see the lens and/or camera body manual for full compatibility information with the Extender EF 1.4X II. AF speed and IS function may be limited or not functional when used with a extender. If your lens is not Canon manufactured or is not mentioned in the above list please bring the camera and lens you would like to use with this convertor when you come to pick up your rental to ensure function before leaving.