-Retains all metering and AF functions with most CANON EF lenses
-High level water and dust resistance -- suitable for use in heavy rain
-O-ring seals protect mounts and release lever
CANON EF Extenders increase the power and versatility of existing lenses. EF Extenders work by increasing the distance between the film plane (or CCD) and the rear element of the lens. The extra distance increases the effective focal length of the lens to bring distant subjects closer.
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.