Canon EF Lens Technology
Input pluse board for electronic manual focusing |
Full-Time Manual (FT-M) Focusing
Canon EF lenses and EOS cameras have very high AF precision. Optimum focus can be achieved quickly for almost any shooting situation. Recent EOS cameras have been equipped with multiple focusing points for higher flexibility in composing a photo while using AF.
Picture-taking is even more flexible with Canon's full-time manual focusing which overrides the autofocusing mode. Lenses with this feature allow you to switch to manual focusing even in the AF mode. You can keep looking through the viewfinder and touch up the focus manually without switching the focus mode switch. Since the focusing ring does not rotate during autofocusing, Canon could make it wider for better holding comfort and easier manual focusing. Another ergonomic design which lets you convey your intentions quickly.
Full-time manual focusing comes in two types. One is electronic manual focusing where the rotation amount of the focusing ring is detected and the focusing motor is driven electronically. The other type is mechanical manual focusing where the rotation of the focusing ring adjusts the focus mechanically.
Full-time mechanical manual focus mechanism |
EF Lens Mount
Large, Fully Electronic Mount System
The conventional interface between the lens and camera body was mechanical, with the use of engaging levers and gears. This method caused physical problems such as wear and rattle. It was limited and more diverse information could not be exchanged. Canon EF lenses do not use such mechanical links at all. About 50 items of information are exchanged as digital signals between the lens and camera in real time. This enables high-speed and high-precision control. And since the lens mount diameter is an ample 54 mm, special lenses such as large-aperture lenses and TS-E lenses can be used. The EF mount is an advanced interfacing system with infinite possibilities.
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