Canon 17-40mm f4 L USM

Features CANON 17-40mm f4 L USM

• Optical performance superior throughout the zoom range.
• Fastest AF speed in its class (similar to that of the EF 16-35mm f/2.8 L USM lens)*
• Highly resistant to dust and moisture
• Minimum focusing distance of 28 cm at all focal lengths *as of January 2003

The ultra-wide lens for analog EOS SLR cameras
EF 17-40mm f/4 L USM is an ultra-wide-angle CANON EF zoom lens designed for professional and non-professional EOS SLR camera users with advanced knowledge.

Standard zoom lens for digital EOS SLR cameras
While an excellent lens when used with an analog SLR camera, the EF 17-40mm f/4L USM lens is especially recommended for digital SLR cameras that have an image sensor smaller than the 35mm format. In fact, on these digital SLR cameras these focal lengths can offer an angle of view roughly equivalent to what a 28 to 70mm lens uses on a 35mm camera, making it the ideal standard zoom lens.

superior optical performance
The EF 17-40mm f/4 L USM features 12 lens elements organized into 9 groups. The Super Spectra coating of the elements ensures an excellent color balance, as well as minimizing glare and shadows. To provide superior image quality over a zoom range ranging from 17 to 40 mm, the lens uses three aspherical elements of two different types, while Super UD (Ultra-low Dispersion) glass is used to avoid chromatic aberrations that usually decrease the clarity of the edges of the subject clearly.

Comprehensive set of top-notch features
The minimum focusing distance is only 28 mm over the entire zoom range.

Autofocus has quiet and fast operation thanks to the central processing unit that uses an improved AF algorithm. If you wish, you can override AF mode and use manual focus.

The circular aperture of the EF 17-400mm f/4 L USM lens, controlled by an electromagnetic diaphragm, can bring a more attractive look to out-of-focus background areas of an image.

The front of the lens does not rotate while focusing. For example, this means that polarizing filters continue to work perfectly as you zoom in and out. On the back of the lens is a drop-in gelatin filter holder.

Due to its high resistance to moisture and dust, the EF 17-40 mm f/4 L USM lens is especially recommended for use in difficult environmental conditions. Lead-free glass is used to protect the environment throughout the construction.