Thank you for purchasing a Canon product.
The Canon EF17-40mm f/4L USM is a high- performance wide-angle zoom lens.
• “USM” stands for Ultrasonic Motor.
Conventions used in this instruction
Warning to prevent lens or camera malfunction or damage.
Supplementary notes on using the lens and taking pictures.
Features
1.Two aspherical elements and a Super UD element result in outstanding image delineation.
2.Ultrasonic motor (USM) for quick and quiet autofocusing.
3.Manual focusing is available after the subject comes into focus in autofocus mode (ONE SHOT AF).
4.A truly round aperture hole results in a nicer background blur.
5.Tight seal structure ensures excellent dust- proof and drip-proof performance.
•Since the front element of this lens moves when focusing (zooming), you need to attach a Canon PROTECT filter sold separately for adequate dust- and