Nikon Nikon UW 20mm f2.8 Heritage

Overview

The Nikon UW-Nikkor 20mm f/2.8 was developed as part of Nikon's legendary Nikonos underwater camera system, which began in 1963 when Nikon acquired the rights to Jacques-Yves Cousteau's Calypso camera design. The UW-Nikkor 20mm f/2.8 emerged in the early 1980s as an essential tool for serious underwater photographers who needed a wide field of view to capture marine life and underwater environments. Unlike standard Nikon F-mount lenses, this was a dedicated underwater optic designed to be used exclusively submerged—it cannot focus properly in air due to the optical calculations being based on the refractive index of water. This lens represented Nikon's commitment to the professional underwater photography market and was engineered with water-contact optics, meaning the front element is designed to interface directly with water rather than air. The Nikonos system cultivated an almost religious following among underwater photographers, marine biologists, and documentary filmmakers. The 20mm was particularly beloved because it offered a near-ideal balance of wide coverage (approximately 94° underwater) while maintaining excellent sharpness for documenting reef systems, shipwrecks, and large marine animals. When Nikon discontinued the Nikonos system in 2001, these lenses became highly sought-after collectibles and remain workhorses for dedicated film underwater photographers who refuse to abandon the system.

Verdict: The Nikon UW-Nikkor 20mm f/2.8 is a specialized tool of exceptional quality for a very specific purpose: film-based underwater photography using the Nikonos system. It delivers optical performance that justified its professional-grade price when new and remains the benchmark for dedicated underwater wide-angle lenses. This is not a lens for casual shooters or those seeking versatility—it literally cannot function above water. It belongs in the hands of dedicated underwater film photographers who appreciate the Nikonos system's unique workflow, marine biologists documenting field work on film, or serious collectors of Nikon's professional legacy equipment. For these users, it represents an irreplaceable piece of underwater photographic history with image quality that still impresses decades after its introduction.

Optical Character

Bokeh

Due to wide focal length, extensive depth of field is the norm; when shallow DOF is achieved at close focus, out-of-focus rendering is smooth and unobtrusive.

Color

Neutral to slightly cool color rendering underwater, designed to work harmoniously with blue-green dominant underwater spectrum.

Sharpness wide open

Exceptional sharpness across the entire frame when submerged; center sharpness outstanding wide open, peak performance at f/5.6-f/8; cannot achieve proper focus in air by design.

Flare resistance

Well-controlled flare with effective multi-coating; maintains good contrast when shooting toward sunlight penetrating water surface with minimal veiling glare.

Contrast

Strong micro-contrast for excellent detail rendition on textured surfaces; moderate global contrast preserves shadow detail in challenging underwater lighting.

Vignetting

Minimal vignetting at f/5.6-f/8; slight corner shading at f/2.8 but rarely objectionable and often masked by natural underwater light falloff.

Community Insights

What people love

Purpose-built optical design optimized for underwater use delivers sharpness that surface-adapted lenses cannot match when submerged
The 94° underwater field of view is ideal for environmental portraits of large marine animals, reef systems, and wreck photography
Robust mechanical construction with proper sealing designed for repeated saltwater immersion
Part of the legendary Nikonos system with decades of proven reliability in demanding conditions
Maintains excellent contrast and color fidelity in challenging underwater lighting conditions
Relatively compact size compared to housed SLR wide-angle solutions
The f/2.8 maximum aperture allows for available-light shooting in shallow, clear water

What people dislike

Cannot be used on land or in air—the lens simply will not focus properly above water, making it a single-purpose tool
The Nikonos mount is a dead system with no new bodies being manufactured, limiting long-term usability
Requires commitment to film-based underwater photography in an era dominated by digital housings
Finding qualified service technicians for Nikonos equipment is increasingly difficult
The fixed nature of the system (no zoom, no autofocus) demands significant skill and experience
Replacement parts are becoming scarce and expensive as the system ages

Pro Tips

Always test the lens in a controlled pool environment before taking it on important dives to verify seal integrity
Soak the lens in fresh water immediately after saltwater use and allow to dry completely before storage
Replace O-rings annually or more frequently with heavy use—use only proper silicone grease
For optimal results, shoot at f/5.6-f/8 to balance depth of field with diffraction limits
Use a quality strobe positioned to avoid backscatter and restore colors lost to depth absorption
Focus carefully using the depth scale; underwater estimation takes practice to master
Store with a small packet of silica gel in a sealed container to prevent fungus growth
The minimum focus distance underwater is approximately 0.3m—excellent for reef close-ups with environmental context

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LLM generated secondaryAI

The Nikon UW-Nikkor 20mm f/2.8 was developed as part of Nikon's legendary Nikonos underwater camera system, which began in 1963 when Nikon acquired the rights to Jacques-Yves Cousteau's Calypso camera design. The UW-Nikkor 20mm f/2.8 emerged in the early 1980s as an essential tool for serious underwater photographers who needed a wide field of view to capture marine life and underwater environments. Unlike standard Nikon F-mount lenses, this was a dedicated underwater optic designed to be used exclusively submerged—it cannot focus properly in air due to the optical calculations being based on the refractive index of water. This lens represented Nikon's commitment to the professional underwater photography market and was engineered with water-contact optics, meaning the front element is designed to interface directly with water rather than air. The Nikonos system cultivated an almost religious following among underwater photographers, marine biologists, and documentary filmmakers. The 20mm was particularly beloved because it offered a near-ideal balance of wide coverage (approximately 94° underwater) while maintaining excellent sharpness for documenting reef systems, shipwrecks, and large marine animals. When Nikon discontinued the Nikonos system in 2001, these lenses became highly sought-after collectibles and remain workhorses for dedicated film underwater photographers who refuse to abandon the system.