The EF 70-300mm f/4.5-5.6 DO IS USM Lens from Canon
is a relatively compact telephoto zoom offering superior
maximum-aperture performance across its entire focal length range. It
incorporates Canon's DO (Diffractive Optics) and IS (Image Stabilizing)
technologies.
The use of Diffraction Optics allows a lens to be
shorter, lighter, and of higher image quality than comparable normal
optical systems of the same focal length and aperture-while this lens is
heavier than the consumer-grade EF 70-300mm f/4-5.6 IS USM lens, it is
28% shorter and uses Canon's very best ring-USM (ultrasonic) motor
instead of the lighter, slower, and less costly 'micro-USM' motor.
The
DO lens performs admirably at its maximum aperture, with images that
are very comparable to the "L" series telephotos. It has a circular
aperture diaphragm to help create natural out-of-focus highlights, and
its built-in two-mode image stabilizer allows you to handhold the lens
at shutter speeds 3 steps slower than would otherwise be possible. Mode 1
corrects vibrations in all directions and is best for still subjects
whereas Mode 2 is best when following moving subjects either
horizontally or vertically.
The lens' AF is super-fast and silent
with a ring-type USM that focuses down to 4.6', and it enables ;manual
focus override for precise manual focus even in AF mode. It also
features a zoom lock button that keeps the lens safe and secure when not
in use or when being used at the shortest 70mm focal length
setting. ; ;The EF 70-300mm f/4.5-5.6 DO IS USM is an ideal lens for
sports, portraiture, animals, and other applications when you're
shooting in relatively bright light.