After months of testing and its initial announcement in February 2011, Canon has made the EF 200-400mm f/4L IS USM Extender 1.4x lens available to the mass market. The Canon EF 200-400mm f/4L IS USM Extender 1.4x has been trialed extensively by professional photographers before its official launch and was known to be used at the London 2012 Olympic Games and by wildlife photographer, Andy Rouse, who has conducted his own test based on using the lens over a six month period.

We first laid hands on the Canon EF 200-400mm f/4L IS USM Extender 1.4x at this year’s Focus on Imaging show and have a first-look video, which looks at how the 1.4 Extender works.

The EF 200-400mm f/4L IS USM Extender 1.4x features a 200-400mm focal range with a fixed f/4 aperture, 4-stop optical Image Stabilizer and for the first time in a commercially available lens, a built-in 1.4x extender that slots in at the rear of the lens from a flick of the 1.4x Extender switch.

Designed for professional wildlife an sports photographers, the lens features a robust magnesium alloy design, environmental protection and specialised lens coatings also make it ideal for mobile use, combining with the finest quality optics to deliver exceptional results, even in the harshest conditions.

The hefty £11,999 price tag that it comes with suggests this is a lens that will be out of reach for most enthusiast and semi-pro photographers. It’s therefore more likely to be hired by professional photographers and agencies for the times that it’s required – much like the Nikon 800mm f/5.6E FL ED VR lens that has a £15,600 price tag.

A newly designed optical Image Stabilizer, which provides users with a four stop advantage, while IS ‘Mode 3′ applies image stabilisation only at the time of exposure – ensuring that photographers can pan with fast-paced action without IS overcompensating for movement. This feature is ideal for sports photographers, who typically have only a split-second to capture a subject in front of them.

The EF 200-400mm f/4L IS USM Extender 1.4x features Canon’s pioneering ring-type Ultrasonic Motor providing fast, silent autofocusing. For those who prefer to fine-tune focus themselves, full-time manual override allows photographers to manually focus at any moment when using AF. The Power Focus (PF) mode also increases versatility during movie shooting with the EOS-1D C or EOS-1D X, enabling photographers to achieve an accurate pull-focus effect at one of two speeds, simply by twisting the focus recall ring and stopping at a pre-set distance.

The tough magnesium alloy chassis ensures that, despite the inclusion of the 1.4x extender, the lens is a similar weight to lenses of comparable focal length. Fluorine coatings on the front and rear lens elements also reduce the ability of dirt to cling to the lens surface, while a dust and water-resistant construction allows photographers to shoot in challenging weather conditions. The combination of outstanding optical performance, versatility, weight and tough construction will make it an essential part of any professional sports or wildlife photographer’s kitbag.

Available from the end of June, the Canon EF 200-400mm f/4L IS USM Extender 1.4x will cost £11,999.