New Canon Lens EF 17-40mm f/4L USM - ultra-wide zoom with high performance autofocus
Amstelveen, The Netherlands, 2003 - Canon, the leader in photographic and imaging technology, introduces a new high quality ultra-wide angle zoom lens - the EF17-40mm f/4L USM. This new model offers a wider zoom range, with both wider and longer focal lengths, as well as a constant maximum aperture of F4 and autofocusing speed at least equal to that of the class leading EF16-35mm f/2.8L USM lens.
While the 2.4x, 17-40mm, zoom range provides excellent versatility and creativity for the film camera user this set of focal lengths will also be particularly useful to digital SLR users. When used with an APS-C sized imaging sensor, as is used in the new Canon EOS 10D and the existing EOS D60, these focal lengths give an angle of view in a similar range to that of a 28-70mm lens when used on a standard 135 format camera.
This new lens will be welcomed equally by film and digital camera users.' Says Hiroshi Komatsuzaki, Head of Canon Consumer Imaging. 'Its focal length range and the unique Canon technologies used in its design and construction will provide photographers with an indispensable high quality, well corrected, optical tool.'
Minimum flare, maximum focus
To ensure distortion-free images the EF17-40mm f/4L USM uses three aspheric elements of two different types, while Super UD glass is used to prevent the chromatic aberrations that often degrade subject edge clarity. Additionally, lens coatings have been employed to inhibit ghosting and flare caused by internally reflected non-image forming light. By increasing the power of the group of elements controlling focus Canon has brought the close focus point of the lens to just 0.28m at all focal lengths.
Canon's EMD (electromagnetic diaphragm) gives a more attractive appearance to out of focus picture areas by means of a circular wide aperture diaphragm that produces smoother tonal transitions. A second diaphragm in this unit is used to further reduce the risk of flare and to improve overall contrast in captured images.
Very fast and quiet, AF has been achieved using rear element movement driven by Canon's unique ring type Ultra-Sonic Motor. This internal focusing method allows more convenient use of filters, such as circular polarisers, over the front element, as this element does not rotate as focus points change. For more general filter use the EF17-40mm f/4L USM provides a gelatin filter holder close to the rear element. Manual focus may be used at any time even if the AF system is engaged. Improved environmental sealing has given this lens extra protection against moisture and dust penetration.
The EF17-40mm f/4L USM comes with a petal-shaped lens hood (EW-83E) and soft case LP1319.