Canon EF 17-40mm f/4L USM

An 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 www.camera.co.id  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

Optimized for Digital Imaging
High Speed Rear Focusing
Close Focusing to 11 inches
Non Rotating Front Element
Rear Gel Filter Holder
Shorter and about 35% lighter than 16-35 f/2.8 L-Series Lens

Construction: 9 groups /12 elements
Angle of view: 104° - 57°
F stop range: 4-22
Closest Focusing Distance: 0.28m / 0.9 ft.
Maximum Magnification: 0.24 (at 40mm)
Filter Size 77mm
Dimensions (Length x Diameter): 3.3" x 3.8" / 83.5mm x 96.8mm,
Weight: 500g , 17.6 oz.