Canon 17-55mm f/2.8 EF-S IS USM (1242B005)

From the manufacturer's press release:

"Canon is expanding its EF-S lens series with the introduction of the versatile EF-S 17-55mm f/2.8 IS USM lens with Image Stabilizer. In terms of image quality and construction, the EF-S 17-55mm f/2.8 IS USM is virtually unmatched. inferior to the latest of Canon's renowned professional lenses, the new lens boasts the fastest zoom speeds at standard focus distances and can be used on cameras equipped with an EF-S series lens mount, such as the new EOS 30D. The latest 3-stage Image Stabilizer provides exceptional performance for this versatile lens, as well as flexible framing in low light conditions. .

High image quality

Two UD elements (Ultra-Low Dispersion Lenses) are used to improve image clarity in all areas of the frame. These elements help eliminate residual chromatic aberrations that reduce image sharpness and colour quality. To ensure sharpness and high contrast in all areas of the frame, two aspherical lenses are used to avoid spherical aberrations that make the image blurry, especially at wide apertures. Combined with the CMOS image sensor found in EOS digital cameras and the DIGIC II image processor, the EF-S 17-55mm f/2.8 IS USM delivers image quality that surpasses even the demands of commercial photography.

Fixed aperture f/2.8 at focal lengths from 17 to 55 mm

High optical quality at a fixed aperture throughout the zoom range allows photographers to set exposure at the widest aperture and concentrate on framing without worrying about adjusting shutter speed at longer focal lengths. The lens is equipped with an almost round convex aperture, which allows you to create a beautiful blurred background.

Image Stabilizer

This lens uses Canon's latest three-stage Image Stabilizer to noticeably reduce blur caused by camera shake. Image Stabilizer greatly enhances the ability to shoot in low light conditions without using a flash, increasing the depth of field. The three-stop system allows the photographer to shoot in low light at a shutter speed of 1/15s instead of 1/125s without any noticeable increase in image blur.

The Image Stabilizer automatically detects the position of the camera on the tripod, preventing feedback between the vibration of the Image Stabilizer sensor and the stabilizer motor.

(For more information on Image Stabilizer, see the Technology Description appendix.)

Fast and silent autofocus

The Ultrasonic Motor (USM) generates ultrasonic frequency oscillations for high-speed, near-silent autofocusing. A constant torque motor moves the focus lens group at high speed and stops it exactly when it reaches the desired focus point; this ensures correct focus on the subject on the first try. Full manual focus is also possible, and the user can do it without switching the lens out of autofocus mode by simply turning the focus ring.

Reducing stray light reflection

By refining the Super Spectra lens coating and lens shape, Canon's developers have been able to reduce the ghosting and flare that occurs when using digital cameras due to reflection from the image sensor. By increasing light absorption, Super Spectra coating reduces the reflective effect of the lenses, resulting in bright, clear images with natural colour reproduction.

EOS system integration

When used with Canon EX-series Speedlites, as well as the built-in flashes of the EOS 350D, EOS 20D and the new EOS 30D, the lens transmits distance information to the E-TTL II flash algorithm; this results in more accurate exposure metering.

An optional lens hood designed specifically for the EF-S 17-55mm f/2.8 IS USM and a case are also available.

In keeping with Canon's "Kyosei" philosophy of living in harmony with the environment, Canon lenses are made only from lead-free glass."