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The EF 70-300mm f/4.5-5.6 DO IS USM is the world's only zoom lens to incorporate a DO element. Introduction of a new triple-layered DO element not only makes the lens more nimble, it delivers unrivalled imaging performance. The DO element is combined with normal refraction elements to compensate for colour aberration. This achieves levels of colour aberration correction that could previously only be achieved with the use of fluorite elements or Ultra-low Dispersion (UD) lenses. The result: superb image quality in an exceptionally small package. Canon's renowned Image Stabilizer (IS) technology compensates for approximately three stops without perceptible increase in image blur. This increases vastly the range of circumstances in which hand-held photography is possible, limiting the need to carry a tripod. Major movement in a particular direction is automatically detected as conscious panning. Correction is halted in the relevant direction, thereby preventing shake-return. The ring-type USM delivers high-speed, high-precision, super efficient and virtually noiseless auto focusing, with good holding torque for rapid response, accurate stopping. Use of USM also allows full-time manual override without damage to the autofocus mechanism. Aperture is controlled with an EMD (electromagnetic diaphragm) for fast, quiet, highly precise control and the lens incorporates a circular aperture diaphragm for pleasing background blur. The drive pattern of the lens is tailored to specifically match that of the latest EOS range, extracting maximum benefit from the lens’ speed advantage. Distance information offers higher precision focus-linked E-TTL II flash photography metering. In keeping with Canon’s stringent environmental policy, only lead free glass is used in the lens’ optics.
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