This dedicated APO teleconverter can be mounted between select lenses and the camera body to increase the focal length by the power of 2. It is compatible with the lens autofocus function, depending on the open-aperture F value of the lens being used, and they work with the AE (Automatic Exposure) function, dispensing with complicated exposure calculations. It also offers maximum photography magnification by 2x, without any variation in the minimum focusing distance. Compact and lightweight, this teleconverter converts your lens into longer focal-length lens, so you don't have to do a lot of unnecessary footwork.Using the 2x APO Tele Converter EX decreases the effective aperture by two F-stops.

The Sigma APO Teleconverter 2x EX DG for Canon Digital SLR Cameras is a dedicated APO teleconverter that can be mounted between select lenses and the camera body to increase the focal length by the power of two. The multi-layer coating reduces flare and ghosting, which is a common problem with digital cameras. The lens also offers maximum magnification without any variation in the minimum focusing distance. Compact and lightweight, this teleconverter can convert your lenses into longer focal-length lenses, so you don't have to do a lot of unnecessary footwork. A case for the lens is included.