Nikon 20mm f/2.8 UW-NIKKOR Underwater Lens for Nikonos Cameras *USED*

Quick Overview

• Engineered specifically for underwater photography environments.
• Fixed 20mm wide-angle focal length.
• Bright f/2.8 maximum aperture for low light.
• Provides expansive 94-degree underwater field view.
• Optics corrected for water refractive index.
• Extremely sharp image quality when submerged.
• Does not function for above-water photography.
• Reliable manual focus operation in water.
• Built for rugged, high-pressure underwater use.
• Compatible with standard Nikonos camera system.

Product Description

The Nikon 20mm f/2.8 UW-NIKKOR is a specialized wide-angle prime lens engineered exclusively for the Nikonos underwater camera system. Unlike standard lenses, its entire optical formula—comprised of 11 elements in 10 groups—is specifically calculated to compensate for the higher refractive index of water compared to air. This results in a corrected image that minimizes distortion and chromatic aberration underwater, providing a true 20mm field of view that is optically optimized for the aquatic environment, meaning it will not focus correctly if used on land.

Designed for the rigors of diving, the lens features a rugged, corrosion-resistant exterior built to interface with the Nikonos bayonet mount. All mechanical controls, including the aperture and focus rings, are oversized and deeply knurled to ensure reliable operation even when the photographer is wearing thick neoprene diving gloves. The lens utilizes an automatic diaphragm mechanism that couples directly with the camera body, allowing the user to compose and focus with the aperture fully open, stopping down automatically to the selected f-stop only at the moment of exposure.

The lens offers a fast maximum aperture of f/2.8, which is crucial for maintaining shutter speeds in the lower-light conditions of deep-water environments. It stops down to f/22, providing the deep depth-of-field control necessary for wide-angle underwater subjects. The front element is protected by a heavy-duty, integrated lens housing, and the optical design includes a floating element system to maintain consistent sharpness across the focusing range, which extends from a minimum focus distance of 0.2 meters (approximately 8 inches) to infinity.