Nikon Nikonos II Underwater Camera w/35mm f2.8
The Nikonos II is the successor to the original Calypso underwater camera, licensed to Nikon and re-introduced as the Nikonos. The Nikonos II was made from 1968-1975, and aside from the II markings beside the viewfinder, it adds a fold-out film rewind crank and an improved film pressure plate. A version branded as Calypso/Nikkor II was sold in Europe.
The Nikonos II can be used at depths up to 50m (160 feet, 26.67 fathoms). It uses 35mm film for a 24x36mm image size, has a focal-plane shutter with vertical travel and X & FP flash sync options (highest X-sync is at 1/60), and offers shutter speeds of 1/30,1/60, 1/125,1/250,1/500 and Bulb. The viewfinder has 35mm coverage and parallax correction marks for close-ups. The body is die-cast aluminium alloy sealed with O-ring gaskets.
The standard lens is a Nikkor 35mm f/2.5 with zone focusing and a useful depth of field scale. Unlike on the original Nikonos, the "II" version has a dual feet/meters distance scale and re-introduces the white lines from the Calypso lens to indicate which knob controls which function. The protective planar glass front of the 35/2.5 lens permits its use both above and below water. (When submerged, the stronger refraction of water yields a field of view equivalent to a ~47mm lens on land.)