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.