The Calypso is equally suitable for water and air environment photography. It consists of two black enameled cast alloy body parts; the one with all the internal parts is lowered into the outer shell. They are locked together when the interchangeable lens is mounted on the camera, and sealed by Vaseline greased O-rings to form a watertight unit. At the top, the Calypso has a built-in optical viewfinder for the 35mmstandard lens, and an accessory shoe on the top for separate viewfinders to suit various purposes. The body is covered in a grey sealskin imitation. Two carrying strap attachments doubles as opening levers to be hooked under the top protrusions either side and forced downwards to lift the top out when no lens is mounted on the camera. The most unusual feature is the combined wind-on and shutter release lever. It swings out forward 65 degrees and is operated by the index finger. In the stowed-away position, the shutter is cocked and the film wound on ready for the next picture. A small rocking lever in front of the accessory shoe serves as a shutter-release lock at this stage, it is disengaged by sliding it to the left-hand side. Depressing the lever releases the shutter and it relocates to the 65 degrees standoff position. Depressing the lever again cocks the shutter and winds on the film. At the camera base is a special flash sync connector protected by coin-operated O-ring sealed aluminium plug, as well as an automatic resetting frame counter, visible behind a glass window. No tripod socket is provided. A small rewind knob at the left-hand top is extended for easy access and to engage the film transport mechanism. No rewind release facility is required; a function that was later added to the Nikonos and marked R on the shutter-speed dial. The original lenses are listed below; however all later Nikonos UW-Nikkor lenses are compatible.
SOM Berthiot 1:3.3 f=28
SOM Berthiot 1:3.5 f=35
Angénieux 1:2.8 f=45mm
The standard SOM BERTHIOT 1:3.5 f=35 lens is used both underwater and above due to the optical flat protecting front glass, but the lens has no filter thread at the front. Two large aluminium knobs either side of the lens provides aperture and focusing controls. The special Calypso lens mount is of the bayonet variety with an O-ring sealing. The spring action of the O-ring locks the lens in place by two pins engaging in corresponding slots in the periphery of the lens mount. The lens release is accomplished by an outward pull and a quarter turn either way. Inside, the film cassette engages the rewind fork at the top, and it is held in place by a hinged retaining ring at the bottom. The film lead passes under the fixed black film-pressure plate on its way to the slotted large diameter take-up spool. The spool always rotates the same angular amount to advance the film without a sprocket wheel drive. Acceptable frame spacing is accomplished by the large diameter take-up spool that reduces the effect of increasing spool diameter as more film is wound onto it.
Variants
The vertical runningmetal-plate focal-plane shutter of the original Calypso has speeds from 1/30 to 1/1000 second, but a year later that was changed to 1/15 to 1/500 second. The camera was very early on advertised, and possibly sold as, the Calypso Phot. In order to reach a larger market the design was sold to Nikon in Japan, and in 1963 released as the Nikonos, subsequently becoming a long-lived series of underwater cameras, culminating with the introduction of the short-lived 35mm SLR Nikonos RS in 1992.
