Canon EF 17-40mm f/4.0L USM Wide Angle Zoom (Demo)

While this is an excellent ultra-wide zoom lens for analogue (film) SLR cameras, this lens is especially well suited for digital SLR cameras which usually have an imaging sensor size smaller than the 35mm format. When used with such digital SLR cameras these focal lengths can give an angle of view approximately equivalent to that of a 28-70mm lens used on a 35mm camera, which makes it the ideal standard zoom lens.

Key Features:

• Rear gelatin filter slot accepts up to three gel filters, allowing for a multitude of different combinations
• Lens retains the popular 77mm filter size shared by other Canon "L" zoom lenses
• Lens uses three aspheric elements of two different types, while Super UD (Ultra-low Dispersion) glass is used to prevent the chromatic aberrations that often can degrade the subject edge clarity
• Entirely internal focusing and zooming movement
• Dust and moisture resistance is equal to the professional levels of the EOS 1-V and 1-D cameras
• Circular aperture diaphragm produces brilliant out-of-focus characteristics

All of the "L" lenses deliver optical performance equal to similiar fixed focal length lenses, and the USM lenses do this with silent, high-speed focusing. Distortions and aberrations are remarkably small for a lens of such amazing capabilities.

A new and affordable L-series ultra-wide-angle zoom lens that's ideal for both film and digital SLRs. Superior optics are assured by the use of three aspherical lens elements, in addition to a Super UD (Ultra-low Dispersion) glass element. Optical coatings are optimized for use with digital cameras. This lens focuses as close as 11 inches (0.28m), and offers both Canon's full-time manual focus and a powerful ring-type USM for fast and silent AF. It has a constant f/4 maximum aperture, and offers the choice of screw-in 77mm filters or a holder in the rear of the lens for up to three gel filters. Finally, it offers weather-resistant construction similar to other high-end L-series lenses.