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 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 

Ultra-wide or standard zoom 
The EF 17-40mm f/4L USM acts as an ultra-wide angle zoom on film or full-frame digital EOS cameras. On DSLRs equipped with APS-C sized sensors it acts as a standard zoom, giving an angle of view equivalent to a 28-70mm lens on a full-frame camera. 

Close focusing 
Minimum focusing distance is just 28cm throughout the entire zoom range. 

Superior optical performance 
The EF17-40mm f/4L USM has 12 lens elements arranged in nine groups. Super Spectra coating ensures excellent color balance and minimizes ghosting and flare. To provide superb image quality over the complete 17-40mm zoom range the lens uses three aspheric elements. Super UD (Ultra-low Dispersion) glass prevents chromatic aberrations. 

Ultrasonic focusing 
A ring-type ultrasonic motor drives autofocus extremely quickly, and in near silence. Excellent holding torque ensures the point of focus is reached accurately, without overshooting. Furthermore, full-time manual override is available, making it possible to adjust focus without leaving AF mode. 

Non-rotating front element 
The front of the lens does not rotate, which makes using specialized filters, such as polarizers and graduates, easier. A drop-in gelatin-filter holder can be found at the back of the lens. 

Smooth background blur 
A virtually circular aperture diaphragm gives out of focus regions a softer, more uniform feel. Sharp foreground objects stand out against a smooth blurred background. 

Weather resistant 
Highly resistant to moisture and dust, the EF17-40mm f/4L USM is ideally suited for use in harsh environments. Environment friendly lead-free glass is used throughout its construction.

Compatibility: 
• EOS 7D Mark II 
• 7D 
• 80D
• 77D
• 70D
• 60D
• 50D
• 40D
• 30D
• 20D
• Rebel T7i
• Rebel T6s
• Rebel T6i
• Rebel T5i
• Rebel T4i
• Rebel SL1
• Rebel T3i
• Rebel T6
• Rebel T5
• Rebel T3
• Rebel T2i
• Rebel T1i
• Rebel Xsi
• Rebel XS
• Digital Rebel Xti
• Digital Rebel XT
• Digital Rebel only


The Canon 17-40mm is commonly used for Art, Fun, General purpose, Landscape/scenery, Landscape photography, Low light, Night photography, Photojournalism, Portraits, Special effects, Sports/action, Travel, Upgrade, Video, Weddings, Wildlife, Wildlife photos and more.The Canon 17-40mm is most used by customers who consider themselves to be a Casual photographer, Enthusiast, Photo enthusiast, Professional, Pro photographer, Semi-professional, Semi-pro photographer among others.The Canon 17-40mm is popular because customers like the following qualities of the Canon 17-40mm: Clear glass, Consistent output, Durable, Easily interchangeable, Easily mounted, Easy to clean, Fast / accurate auto-focus, Fast auto-focus, Lightweight, Nice bokeh, Rugged, Sharp, Simple controls, Strong construction, Superior build quality and Super-sharp images