Nikon positive accessory lenses

The extension available is 47.5 mm, and the focal length at the close focus point is 76.2 mm.

Corrected focal length = Fc

Nikon makes two-element diopters for lenses with 52 mm filter threads, and for lenses with 62 mm threads.  They also make a few single-element diopters; don't try them unless you like soft-focus effects.

The 52 mm diopters are the 3T (+1.5 diopters) and the 4T (+2.9 diopters).

The 62 mm diopters are the 5T (+1.5 diopters) and the 6T (+2.9 diopters).