Updated 31/1/13: With new info on the lens manufacturing process from Nikon HQ, Tokyo, Japan.
Nikon has announced two brand new lenses; the AF-S Nikkor 800mm f/5.6E FL ED VR lens compatible with the FX mount, and the AF-S Nikkor 18-35mm f/3.5-4.5G ED compatible with the FX as well as DX mount.
The Nikkor 800mm f/5.6 (above) is the longest focal length in Nikon's library of auto-focus lenses. It is also the first Nikkor lens to have fluorite elements, two of them, together with two ED lens elements. According to a Nikon representative we talked with, fluorite was chosen for its weight savings as well as to improve the heft and balance of the lens. Fluorite is known to be brittle and it expands easily under heat, but our Nikon rep explained that the company has apparently solved the problems inherent in the material (probably by using a composite instead of pure fluorite).
It is also Nikon's first lens to be built with an electromagnetic aperture instead of the traditional mechanical aperture. This enables stable exposure control with high-speed continuous shooting and is a necessary change due to the extraordinary length of the lens.
The Nikkor 800mm is equipped with vibration reduction (VR), which Nikon says can compensate for up to 4 stops. Nikon's Nano Crystal Coating helps prevent the internal reflections that cause ghosting and flaring.
A dedicated 1.25x AF-S teleconverter TC800-1.25E ED will be included with the 800mm lens. When paired with the lens, it will increase the focal length to 1000mm with a combined maximum aperture of f/7.1. Auto-focus should be functional with f/8 compatible cameras such as the Nikon D4, D800 and D600.
Also announced is a new AF-S Nikkor 18-15mm f/3.5-4.5G ED lens, a wide-angle 1.9x zoom lens for the FX mount. It has a minimum focus distance of 28cm and is built with two ED and three aspherical lens elements, weighing just 385g. It also comes with its own Silent Wave Motor (SWM) as well as a 7-blade rounded aperture. It's expected to be a low-cost kit lens option for the FX mount.
Both lenses are due to arrive in April. The retail prices have not yet been announced.
On our visit to Nikon HQ in Tokyo, Japan, we met Nikon lens designer Hiroki Harada, who emphasized that it is Nikon's aim to produce lenses which strike a balance between sharpness and contrast.
Harada revealed that Nikon has one of the world's largest glass mold aspherical lens elements. Aspherical elements can be produced either from a mold, from a precision-ground method where the glass surface is ground with a grinding device, or from a hybrid method where special plastic is molded onto optical glass. Harada said that adverse effects are noted in plastics used in the hybrid method when subjected to temperature or humidity fluctuations. Precision-ground lenses take too long and are too costly to produce. Since neither of these two methods are conducive for mass production, Nikon chooses to use molded glass lens elements to provide a balance between price and quality.
Harada also mentioned Nikon's Nano Crystal coating on some of its lenses, and says that it's much more resistant to flare and ghosting than conventional anti-reflection coating. To ensure all Nikkor lenses are up to standard, every step of the lens manufacturing process is done in-house. The glass for the Nikkor lenses is obtained from Nikon's subsidiaries and lenses are individually inspected before being shipped off for sale.