Without a great deal of pomp, but with considerable anticipation, Nikon have just released a new version of their 300mm f/4 lens. So what makes the Nikkor 300mm f/4 AF-S PF ED VR unusual and special?
It is the first Nikon lens incorporating what they call a phase Fresnel element (hence PF). So what does this do? In an over-simplified nutshell it allows light to be bent through a greater angle than normal glass, which results in the light being brought into focus over a shorter distance. The important consequence of this is the size of any lens of a given focal length is reduced.
The distance a normal 300mm lens takes from first bending the light (where light initially hits the glass of the outer element) to where it is brought into focus (on the sensor) is - wait for it - 300mm (this is a simplified definition of focal length).
However, the use of phase Fresnel lens elements reduces this distance, so instead of the 300mm f/4 lens being 222mm in length (as is the conventional Nikkor 300mm f/4 AF-S IF ED), the new Nikkor 300mm f/4 AF-S PF ED VR is only 147.5mm long. There is a corresponding weight reduction of 545 grams as well, from 1300g down to 755g.
This is not new technology as Fresnel lenses (named after their French inventor Augustin-Jean Fresnel) were first used in lighthouses in 1823 and Canon introduced their own version of this technology in 2000 under the banner 'diffractive optics' lenses (DO). These were, and remain, rather expensive - their 400mmm f/4 IS DO USM currently retails for £5400.
The new Nikkor 300mm is somewhat cheaper at £1640. Nikon claim these lenses given incredible optical performance, there is no compromise in quality and images are every bit as crisp and contrasty as with the equivalent conventional lens. Assuming this is so, this new lens is bound to prove popular with wildlife and travel photographers conscious of the weight of their equipment.
One to add to your Christmas list perhaps?