Nikon has published details of an AF-S NIKKOR 50mm f/1.8G lens on its US website. With a built-in Silent Wave focusing motor, this not-yet-formally-announced design should autofocus on all entry-level Nikon DSLR bodies, including the recently-released D5100. It uses an all-new optical design with 7 elements in 6 groups, including one aspherical element. The lens can be used on both FX and DX format DSLRs, with a short-telephoto 75mm-equivalent angle of view on the latter.The web page has now been removed from the Nikon site.

Click here to view the product page on Nikon's USA website

The web page lists the following details about the lens:

Focal length • 50mm
Maximum aperture • f/1.8
Mninimum aperture • f/16
Lens construction • 7 elements in 6 groups (with one aspherical lens element)
Angle of view • 47° (31°30' with Nikon DX format)
Minimum focus distance • 0.45 m/1.48 ft
Maximum reproduction ratio • 0.15x
No. of diaphragm blades • 7 (rounded)
Filter-attachment size • 58mm
Diameter x length (extension from lens mount) • Approximately 72 x 52.5 mm/2.8 x 2.1 in.
Weight • Approximately 185 g/6.6 oz
Supplied accessories • 58mm snap-on Front Lens Cap LC-58, Rear Lens Cap LF-4, Bayonet Hood HB-47, Flexible Lens Pouch CL-1013
The Nikon web page also includes a diagram of the optical formula, which differs from the design of the existing 50mm f1.8D in using 7 elements in 6 groups (as opposed to 6 elements / 5 groups) and including an aspheric lens element - a first for a 50mm F1.8 lens.