Extending a lens's focal length by a factor of 1.4x, the CanonExtender EF 1.4X III incorporates phenomenal optical performance with minimal chromatic aberration and is a perfect complement to many of Canon super telephoto lenses. It features a built-in microcomputer for seamless communication among camera body, lens and extender; features careful lens placement and coatings to minimize ghosting and flare and even has a new Fluorine coating that keeps soiling, smears and fingerprints to a minimum. An integral part of many professional systems, Extender EF 1.4X III maintains high standards not only optically, but also in terms of rugged, dustproof and water resistant construction.
This is the magnifying factor of a lens. Macro lenses will often be described by their “magnification factor”. A lens with a 1:1 magnification factor produces a projected image on the sensor which is the same as the subject.
The individual pieces of glass that form the overall optical construction. Most lenses have between four and eleven elements to bend the light rays to ensure a perfectly formed image appears on the light sensitive surface, such as a film or CCD. The elements are arranged in groups and may be seen in specification sheets as, for example, 6 elements in 4 groups. That configuration may have two single elements and the other four grouped in pairs.