Canon
EF lenses
There is no major difference in principle between a lenses used for a
still camera, a video camera, a telescope, a microscope, or other
apparatus, but the detailed design and construction are different. A
lens may be permanently fixed to a camera, or it may be interchangeable
with lenses of different focal lengths, apertures, and other
properties.
The EF series includes over sixty lenses. The EF series has
encompassed focal lengths from 14 to 1200 mm (and as wide as 10 mm for
EF-S lenses). Many EF lenses
include such features as Canon's
ultrasonic motor (USM) drive, an image stabilization system (IS),
diffractive optics (DO) and, particularly for L-series
lenses, fluorite and spherical lens elements. Canon EF lenses
typically have a number of controls, switches and physical features,
used by the photographer to control the lens. The types and number of
the controls can vary from lens to lens. With the most basic lenses
having only a few, to the most complex having over a dozen different
controls and switches.
Features that can be found on the EF lens just to name a few are;
Focusing ring: This control is found on most EF lenses. It is used for
focusing the lens, so the subject that one wishes to photograph is in
focus. Zoom ring- It is used for changing the focal length of the lens.
Focusing distance range limiter switch: This switch is found on longer
focal length lenses, and macro lenses. It is used for limiting the
focusing distance range of the lens when using it in autofocus mode.
Focusing distance range limiter switch: This switch is found on longer
focal length lenses, and macro lenses. It is used for limiting the
focusing distance range of the lens when using it in autofocus mode.
Image stabilizer switch: This switch is found on all EF lenses that
feature an image stabilizer.
Canon EF lenses typically have a number of controls, switches and
physical features, used by the photographer to control the lens. The
types and number of the controls can vary from lens to lens. With the
most basic lenses having only a few, to the most complex having over a
dozen different controls and switches.
