Four aspherical glass elements reduce distortion throughout the zoom range, achieving superb image quality right across the frame. Ultra-low Dispersion (UD) and Super UD lens elements guard against coloured fringing along high-contrast edges.
• f/4 fixed aperture, high-performance standard zoom L-series lens
• Uses four aspherical lens elements and UD and Super UD lens elements – ensuring the highest image quality
• Canon unique SWC and new ASC anti-reflective coatings
• Fluorine coating on the lens surfaces to prevent dirt sticking to lens elements
• Silent, fast autofocus using a ring type USM
• A nine-blade circular aperture creates beautiful out-of-focus highlights
• Full-time manual focusing
• Minimum focusing distance 0.28m (at 24mm zoom position)
• Highly resistant to dust and water allowing shooting in the harshest conditions
Advanced lens coatings
The EF11-24mm f/4L USM features multiple lens coatings, which minimise the internal reflections that can cause flare and degrade image quality. Canon’s unique Subwavelength Structure Coating (SWC) is applied to two of the lens’ elements, while a new technology – Air Sphere Coating (ASC) – is used on a third element.
Air Sphere Coating has been developed by Canon to minimise reflections and flare. It is a hybrid coating consisting of nano particles that trap capsule-like air between the ASC layer and conventional multi-layer coatings. The Air Sphere particles form a super low reflective coat on the surface of the lens element to reduce reflection and act as a ‘crash mat’ to slow light down to roughly the same speed as light travels through glass, thus preventing the cause of reflection.
Both the SWC and ASC coatings work by slowing down light gradually as it passes from air to glass – abrupt changes in speed can lead to reflections, which spoil image quality. By slowing down light gradually before it passes through the lens, such negative effects are minimised.
Superb optical system
The EF11-24mm f/4L USM uses a patented lens design. The optical design features 16 lens elements in 11 groups with a three group zoom and rear focus. The lens’ use of four aspherical lenses helps to control distortion, keeping it at a very low rate throughout the entire zoom range. The inclusion of both a UD lens and a Super UD lens minimises chromatic aberration that tends to occur mainly around the edges at the wide-angle setting, as well as eliminating colour blurring around the edges of the subject. This ensures high-quality images with high levels of resolution and contrast.
Due to the weight of the front optical group, a new mechanical design was required to support the weight but still ensure a smooth focus and zoom mechanism. The EF11-24mm f/4L USM features the same level of waterproof and dustproof construction as the EF24-70mm f/2.8L II USM and EF70-200mm f/2.8L IS II USM lenses. The mount, the switch panel, zoom ring and focusing ring are all designed to prevent dust and moisture from getting into the lens, making it suitable for taking pictures even in harsh conditions.
The EF11-24mm f/4L USM offers the widest angle of any current fixed focal non-fisheye lens (at the time of writing), whilst offering the flexibility of a zoom. Producing a lens that offers such a wide angle with little distortion and constant aperture is a feat of design and engineering made possible through Canon’s excellence in optics.
Ultimate element protection
Fluorine coatings are applied to front and rear elements allowing the lens’ optics to be kept cleaner by the non-stick properties of the coating, which prevent dust and water drops adhering to the lens elements and make cleaning easier.
Drop-in filter holder
As the front lens element is very large and has a high level of curvature, filters cannot be fitted to the front of the lens, but instead a slip-in filter holder for cut gelatin filters is provided at the rear of the lens.
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06 February 2015
Over the last few years, I've spend a fair amount of time at shows big and small all over the country and one moan I've had has been from Canon users complaining about the fact they've never had a decent usable wide lens. You've either had to go extreme...Read full article