Nikonos V black/orange (also available in all green)
|Type||35 mm underwater viewfinder camera|
|Lens mount||interchangeable Nikonos mount|
|Exposure||TTL automatic exposure & manual|
|Flash||accessory shoe & contacts in base|
|Frame rate||manual wind on|
|Dimensions||146 × 99 × 75 mm (W×H×D)|
Nikonos Calypso is the name of a series of 35 mm film cameras specifically designed for underwater photography launched by Nikon in 1963. The early Nikonos cameras were improvements of the Calypso camera, which was an original design by Jacques-Yves Cousteau and Belgian engineer Jean de Wouters  . It was produced in France by La Spirotechnique (currently Aqua Lung) until the design was acquired by Nikon to become the Nikonos. The Nikonos system was immensely popular with both amateur and professional underwater photographers. Its compact design, ease of use, and excellent optical quality set the standard for several decades of underwater imaging. Nikon ceased development and manufacture of new Nikonos cameras in 2001, but the camera remains popular, and there is a large and active secondary market.
"Calypso" Nikonos viewfinder camera 
The initial Nikonos line consisted of three models that were improved versions of the Cousteau's Calypso (1961):
- Nikonos I Calypso (1963)
- Nikonos II (1968)
- Nikonos III (1975)
Second generation viewfinder camera: Nikon's design 
A second viewfinder line was Nikon's complete re-design and included a through-the-lens (TTL) light meter with automatic exposure:
- Nikonos IV-A (1980)
- Nikonos V (1984)
The various models all had rugged construction, simple controls, and were waterproof to 160 ft (50 m). The camera is made waterproof by a simple system of o-rings at all the crucial joints. Each new generation brought various improvements such as light metering, flash circuitry, and improved shutter and film advance design.
Third generation: SLR and autofocus camera 
- Nikonos RS (1992) waterproof to 320ft (100m)  (World's first underwater Auto-Focus SLR camera) 
Nikonos viewfinder lenses 
The two most common Nikonos lenses are the UW 28mm (for underwater use only) and the W 35mm (which is amphibious) with the UW 28mm being considered the better lens (Jim Church's Essential Guide. It might be helpful to point out that because water and air have significantly different refraction indexes, the slightly wide 35mm lens underwater is equivalent to a standard ~50mm lens above water.)
Many Nikonos lenses, the "UW" series, were specifically designed for underwater photography only. It is said  that, even to this day, no underwater lens matches the Nikonos "UW" lenses for sharpness and color saturation underwater. A brief explanation from Nikon about the difference between underwater-only lens and standard/"amphibious" lens can be found at Niknon official site, under the section "2. Rendition characteristics and lens performance".
Nikon also created two lenses for use both above and under water, and one of them, the 35mm 2.5, can be thought of as the "kit" lens. They made the Nikonos useful for aquatic activities such as kayaking, canoeing, or for foul weather situations. These two lenses, the W-35mm and W-80mm, were also fully waterproof, but because they utilized a flat port, they did not have the benefit of the specialized water-contact optics.
Water resistant (LW) but not waterproof, manual-focus, lenses:
- LW Nikkor 28mm f2.8
Waterproof (W), manual-focus, lenses:
- W Nikkor 35mm f2.5
- W Nikkor 80mm f3.5
Underwater-only (UW), manual-focus, lenses:
- UW Nikkor 15mm f2.8
- UW Nikkor 20mm f2.8
- UW Nikkor 28mm f3.5
Underwater-only (UW), auto-focus (for RS model only) lenses:
- R-UW AF Fisheye-Nikkor 13 mm f2.8 (180 degrees)
- R-UW AF Nikkor 28 mm f2.8 (60 degrees)
- R-UW AF Micro-Nikkor 50 mm f2.8 (35 degrees) Micro (macro 1:1)
- R-UW AF Zoom-Nikkor 20–35 mm f2.8 (80–51 degrees)  (World's first true underwater zoom lens) 
Other lenses and accessories for the Nikonos included:
- Third party compatible lenses made for the Nikonos (e.g., Sea&Sea), which included both prime lenses as well as removable lens adaptors that were externally attached a Nikonos lens;
- Extension tubes mounted with a Nikonos lens for macro photography, most commonly with the 35mm Nikonos lens to produce 2:1, 1:1 and 1:2 macro image ratios, with 1:3 occasionally seen as well;
- Nikon Close Up Kit, which was a removable lens adaptor that was externally attached to typically either the 28 mm, 35 mm, but also the 80mm Nikonos lens, to produce near-macro image ratios (approx range of 1:5 to 1:3);
The Nikonos is often referred to as a rangefinder camera, but in truth it is a scale focus camera as there is no rangefinder. The viewfinder is used purely to compose the shot, and to display exposure information. Focus is set with an outsized dial mounted on the left side of the lens barrel (as seen from the operator's point of view), and the aperture is set with a dial mounted on the right. For many beginners, this meant some confusion over estimating distances underwater, since refraction makes objects appear 25% closer than they actually are. Strangely, Nikon's approach was to assume that the user did not make the correction, so the distance markers on the lens are offset to compensate for it. Thankfully the Nikonos wide-angle lenses have ample depth of field, so these discrepancies are often not a noticeable problem.
Another implication of being a scale focus camera was evident in the extension tube and Close Up Kit systems, as the extremely shallow depth of field for macro photography pragmatically required a focusing aid. The solution used was a framer, which attached to the lens assembly and provided a direct physical index for the camera-to-subject distance, as well as its approximate width/height. These typically only indexed the bottom and two sides, not the top, and because of this shape, a slang term for Nikonos framers were Goal Posts. For various reasons (such as concern for potential damage to the reef), some alternative products were developed over time to minimize or replace the basic framer design. One example (Fred Dion; Underwater Photo Tech) consisted of a bracket that held two small flashlights whose beams aligned at the focus plane.
The "Workhorse of the War" 
Because of its waterproof housing, lens options, and toughness, the Nikonos was an important tool for photographers working in the steaming jungles, flooded rice paddies, and rain-lashed battlefields of the Vietnam War. The wire services loaded their Nikonos cameras with Tri-X, Ektacolor-X or High-Speed Ektachrome.
Nikonos RS 
The 1992 Nikonos RS introduced an entirely new concept. Unlike its predecessors, the RS was a complete amphibious single lens reflex camera, with auto-focus, waterproof to 320ft (100m) and its own set of unique lenses that also utilized water-contact optics. They are, a 50mm f/2.8 macro, 28mm wide, 13mm fisheye ,and the worlds first underwater zoom lens a 20-35mm.
The RS represented the pinnacle of Nikon's commitment to underwater imaging, and generated significant interest at the time. Although groundbreaking in many ways, it was also very expensive, putting it out of reach of all but the most dedicated (or best funded) underwater photographers. Unfortunately, early versions also had a tendency to flood if not maintained perfectly. Flooding was attributed to many factors, one of which was the change to orange-colored silicone o-rings that could swell and fail if third-party silicone grease was applied instead of the Nikonos grease that was petroleum-based. (Non-Nikon (third party) silicon grease was commonly used without problems on black Nikonos o-rings by underwater photographers for several decades.) Nikon replaced all these floods at first, but in the end, it clearly became not worth the trouble. The RS was quietly discontinued about 5 years later, and no subsequent models were ever designed or manufactured.
Nikon continued to manufacture Nikonos V bodies until 2001, when it formally announced it was terminating the series. Without any new models in years and with digital imaging taking over the market, Nikon saw no reason to continue the series.
However, in the French Magazine "Focus-Numerique" Mr. Tetsuro Goto, the Director of Laboratory Research and Development at Nikon Japan said on the future of Nikonos: “personally I think the Nikonos will be reborn in the future.”
Nikonos light meter 
The Nikonos light meter accessory houses the selenium-celled Sekonic L-86 Auto-Lumi. An underwater light meter is necessary for the non-metered Nikonos I, II, and III.
Digital Nikonos 
No Digital Nikonos has ever been made, but Kodak did modify Nikonos cameras for the USA Army which produced the digital "Nikon/Kodak DCS 425". 
- Stafford, Simon (2004). The new Nikon compendium : cameras, lenses & accessories since 1917. New York: Lark Books. ISBN 1-57990-592-7.
- The Best of Popular Photography, Harvey V. Fondiller, ed., Ziff-Davis Publishing Co. New York, 1979
- Kline Jr,, Thomas C. "Evaluation of an underwater single lens reflex camera equipped with automatic focus, automatic exposure and water contact optics". American Academy of Underwater Sciences. Retrieved 26 January 2013.
- Kline Jr., Thomas C. "Nikonos RS Postmortem: The Rise and Fall of the Only Underwater Single Lens Reflex Camera Equipped with Water Contact Optics". American Academy of Underwater Sciences. Retrieved 26 January 2013.
- 'NIKONOS-V camera body to be discontinued', September 18, 2001, , retrieved 03/09/2012.
- James's Light Meter Collection: Sekonic L-86 Auto-Lumi Archived 13 February 2011 at WebCite
- The Secret Behind the Mysterious Digital Nikonos Camera - Gizmodo
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