Canon EF 17-40mm f/4L USM Zoom Lens Get Canon EF 17-40mm f/4L USM Zoom Price / Buy Online

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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.

About half the price of the 16-35 f/2.8 lens, this L-series lens has an entirely new optical design with three Aspherical elements and a Super UD-glass element. The combination provides superb contrast and sharpness, even at the widest settings. It's ideal for both film and digital SLRs, and features the same weather-resistant design, rear gel filter holder, and high-speed Ultrasonic Motor as the EF 16-35mm lens.

Canon EF 17-40mm f/4L USM Zoom Key Features

Ultrasonic Motor

Powered by Canon's exclusive Ultrasonic (USM) motor for autofocusing, the EF 16-35mm f-2.8L USM is silent in operation and very quick to focus, even in low-light conditions. There is virtually no whining noise as the lens focuses to distract the subject or draw attention to the photographer. Most important for the photographer in the field, the motor draws minimal power so the camera batteries last longer.

One Super Ultra-Low Dispersion UD Glass Element

Lenses made from fluorite are extremely expensive due to the high cost of synthetic fluorite crystal production. UD (ultra low dispersion) glass made an appearance in the latter half of the 1970's, delivering a special optical glass which could provide characteristics similar to fluorite but at a lower cost and thereby answering another desire of lens designers. Super UD glass was introduced in 1993 as a new material that achieves almost the same performance as fluorite while achieving a new balance of cost reduction and higher quality.

Three Aspherical Lens Elements

Wide-angle lenses and fast normal focal-length lenses often suffer from an optical problem -- spherical aberration -- which causes an overall softening and optical "smearing" of the image. Canon has developed four different manufacturing technologies to produce Aspherical lens elements, which combat this problem. Aspherical optics, which have an extremely precise variable curvature of one or both sides of a lens element, also allow more compact lens designs and permit lighter lenses with fewer elements.

EF Lens Mount

In designing the EF lens mount, Canon engineers gave photographers a lot more than simply a way to quickly attach an interchangeable lens to a camera body. With the elimination of mechanical connections and the incorporation of an electronic interface between the camera and lens, Canon cameras have greater flexibility with regard to incorporating future technologies and future system upgrades. This fact has already been proven with a vast increase in AF speed, increased functionality such as predictive autofocus systems found in EOS cameras, auto-aperture tilt-shift (TS-E) lenses, the use of ultrasonic motors and the development of the Image Stabilizer lens.

The fully electronic mount system has none of the shock, operational noise, abrasion, play, lubrication requirements, slow response, diminished precision caused by lever operation, or design restrictions related to linkage mechanisms used to transfer data. Furthermore, operation and reliability are significantly improved. And, a lens operation self-test system, using the lens' built-in microcomputer, can even warn of malfunctions through the camera's LCD readout to help ensure high reliability.

Full-Time Manual Focus

Ring-type Ultrasonic Motor allows manual focusing without switching out of the auto mode, making this lens ideal for many photographic applications including sports, photojournalism, portraits, and landscapes.

Inner/Rear Focusing

Focusing is performed by moving one or more lens groups positioned between the front lens group and the diaphragm.

Dust- and Water-Resistant Construction

This EF lens is highly dust- and water-resistant and can therefore be used in harsh conditions without dust and water getting inside.

Canon EF 17-40mm f/4L USM Zoom Specifications

Focal Length

17-40mm

Maximum Aperture

1:4

Lens Construction

12 elements in 9 groups

Diagonal Angle of View

104º - 57º 10'

Focus Adjustment

Inner Focusing System with USM

Closest Focusing Distance

0.28m / 0.9 ft.

Zoom System

Rotating type

Filter Size

77mm

Max. Diameter x Length

3.3" x 3.8" / 83.5mm x 96.8mm

Weight

1.1 lbs. / 500g

Canon EF and EF-S Lenses