Sony is releasing a built-to-order 500mm lens in April.

Weighing in at approximately 3460g, the SAL500F40G telephoto is a dust- and moisture-resistant professional-grade lens for Sony A-mount SLT and DSLR cameras.

Aimed at wildlife and sports pros, the lens delivers a 35mm equivalent of 750mm.

It's the longest fixed focal length G Lens from Sony so far, and it's no surprise to find a super-telephoto of this calibre being released in the year of the Olympics and UEFA Euro finals.

In-keeping with similar optics from the likes of Canon and Nikon, the new 500mm lens offers a maximum aperture of f/4. The lens has been constructed with 11 elements in 10 groups, including three ED (Extra-low Dispersion) glass elements. A new Nano AR Coating process has been used to reduce internal reflections.

These combined features are said to reduce ghosting and lens flare 'dramatically', the latter cut down further by the use of the carbon fibre lens hood which is lined with black velvet fibres.

Autofocus performance

Four focus hold buttons are spaced around the lens barrel to improve handling, while a two-way DMF (Direct Manual Focus) mode button and a focus range switch should speed up operation further.

The high-torque SSM (Super Sonic wave Motor) features a new drive circuit to improve the responsiveness of the autofocus and is said to offer 'significantly' faster subject tracking than conventional Sony lenses.

Like all other A-mount lenses, the SAL500F40G is compatible with the SteadyShot INSIDE image stabilisation system that's featured in every Sony Alpha Translucent Mirror and DSLR. This provides up to 4.5 stops of compensation, according to Sony tests.

Seals around the focusing ring and front/rear joints to protect against dust and moisture complete the picture.

The Sony 500mm f/4 is only available as a built to order option, with UK price to be confirmed. Sony Japan is listing the price of the lens as1,312,500 Yen, which is a whopping £10, 783... better get saving now.