Canon EF 17-40mm F4 L USM Lens

The Canon 17-40mm f/4 USM is an affordable L-series ultra-wide-angle zoom lens that's ideal for both film and digital SLRs. This EF lens focuses as close as 0.28m. 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 3 gel filters. The 17-40mm f4L also features a wear-resistant construction.

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

    Superb optical performance throughout the zoom range
    Fast autofocus speed
    Highly resistant to dust and moisture
    28cm minimum focusing distance at all focal lengths


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 colour balance and minimises ghosting and flare. To provide superb image quality over the complete 17-40mm zoom range the lens uses 3 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 specialised filters, such as polarisers and graduates, easier. A drop-in gelatine-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.

SPECIFICATIONS

Aperture Blades     7
Autofocus Motor     USM
Colour     Black
Enlargement Ratio     1:4.2
Filter Thread Size (mm)     77
Focal Length – Tele (mm)     40
Focal Length – Wide (mm)     17
Hood Model     EW-83E
Included Accessories     Lens pouch, Front and rear caps, Lens hood
Lens Mount     Canon EF
Lens Type     Standard Zoom
Manual Focus Switching     Full Time Manual Override
Maximum Aperture – Tele     4
Maximum Aperture – Wide     4
Minimum Aperture     22
Number of Lens Elements     12
Number of Lens Groups     9
Sensor Format     Full Frame
Size (mm)     83.5 x 96.8 mm
Weight (g)     500
MF switch     Full Time Manual Override
Minimum Focus Distance (m)     0.3