Canon Extender EF 2X III

The Canon Extender EF 2X III is a teleconverter designed for Canon EF-mount cameras, doubling the effective focal length of compatible Canon L-series super-telephoto lenses to extend reach for wildlife, sports, and distant subject photography without purchasing an additional longer lens. As part of Canon’s III-generation extender lineup, it offers improved optical performance and weather sealing compared to earlier Extender EF 2X versions.

The extender mounts between the camera body and a compatible super-telephoto lens, optically doubling the attached lens’s focal length, for example turning a 300mm lens into an effective 600mm, or a 100-400mm zoom into an effective 200-800mm. This gives photographers a cost-effective way to extend reach using lenses already in their kit rather than investing in a dedicated longer super-telephoto optic. As with any 2x extender, using this accessory results in a two-stop light loss, meaning the effective maximum aperture of the attached lens is reduced accordingly, for example an f/4 lens becomes effective f/8 once the extender is attached.

The Extender EF 2X III is compatible only with a specific range of Canon L-series super-telephoto and telephoto zoom lenses designed to accept extenders, since the extender’s rear-mounted lens elements protrude into the lens mount in a way that isn’t compatible with standard lenses; photographers should confirm this extender’s compatibility with their specific lens before use. When paired with a compatible lens and a supporting Canon camera body, the extender maintains autofocus functionality, though AF speed and accuracy can be reduced compared to using the lens without the extender attached, particularly in lower light given the reduced effective aperture.

Build quality includes weather-resistant sealing consistent with Canon’s L-series optics, along with a durable construction intended to withstand the demands of professional wildlife and sports shooting. The optical design was refined in this III generation to improve sharpness and reduce aberrations compared to the earlier Extender EF 2X II, particularly important given that adding a teleconverter can otherwise introduce a noticeable decrease in image quality compared to shooting with the lens alone.

Key Features
– 2x teleconverter for compatible Canon EF-mount L-series super-telephoto lenses
– Doubles effective focal length of attached lens
– Two-stop light loss (e.g., f/4 becomes effective f/8)
– Weather-resistant sealing
– Maintains autofocus with compatible lenses and camera bodies
– Compatible only with extender-compatible Canon L-series lenses (confirm specific lens compatibility)