The EF 17-40mm f/4L USM Lens is a superb L lens from Canon and is great for digital cameras. It offers L quality and reliability at a price not much higher than regular lenses.
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.
Specifications:
- Focal Length: 17 - 40mm
- Maximum Aperture: 1:4
- Focus Adjustment: Inner focusing system with USM
- Angle of view (horizontal, vertical, diagonal): 93° - 49°20', 70°30' - 34°, 104° - 57°30'
- Lens Construction: 12 elements in 9 groups
- Number of diaphragm blades: 7
- Minimum Aperture: 22
- Closest Focusing Distance: 0.28m / 0.9 ft.
- Maximum magnification (x): 0.24 (at 35mm)
- Zoom System: Rotating type
- AF actuator: USM¹
- Filter Diameter: 77mm
- Maximum Diameter x Length: 3.3" x 3.8" / 83.5mm x 96.8mm
- Weight: 1.1 lb. / 500g