This teleconverter provides 2x image magnification at the cost of 2 f-stops of aperture. Some loss of image occurs even when used with L quality telephoto prime lenses. While the 2x can be used with “L” quality telephoto zooms (70-200mm f/2.8 and longer), we don’t really recommend it for the 100-400mm Canon zoom or any 3rd party zoom. On non-1 series cameras, use of a 2x teleconverter will require manual focus on any lens with an aperture greater than f/2.8.
- The Canon 2x will not fit on wide angle or standard zooms, wide angle primes or many third-party lenses.
- If you rent a 2x teleconverter and are using it on any lens other than the Canon 200mm f/2.0 IS, 300mm f/2.8 IS, 400mm f/2.8 IS, 500mm f/4 IS, or 600mm f/4 IS, you are probably not going to be happy with the result, if it works at all. If you decide you want to use it with another lens, do so at your own risk. Please don’t expect us to refund the rental when it didn’t work with your 70-300 f/5.6 zoom.