Nikonos IV A

Lenses: Interchangeable. The 35mm f/2.5 and 80mm f/4 lenses work in water and air. The 28mm f/3.5, 20mm f/2.8 and 15mm f/2.8 lenses only work under water. Standard Lens: 35mm f/2.5 works on land, sea and air. 6-bladed manual diaphragm stops down to f/22. Focus from infinity to 2.75' (0.8m). Filter thread appears to be 58mm. Filter Size (Standard 35mm lens): 58mm screw-in. Focusing: Scale focus only. Guess or measure (tape) the distance and set it on the dial. There is no rangefinder. I'm unsure if the distances correspond to water or air. Depth-of-Field Scale: Magic moving indicators move along the distance scale as you change the aperture. Exposure Dial Settings: Aperture-preferred Auto (A), Mechanical 1/90 (M), Bulb (B) and (R) for rewind. ASA/ISO Range: 25 - 1,600. Shutter: 1/30 - 1/1,000 on Auto, I think. When tested it seems to be able to go for many seconds at night, an excellent plus. My Nikon FE of this same vintage could exposure perfectly for many minutes at night. Flash Sync: Via a three-terminal connector under a screw-tight cover on the bottom plate. Power: Thumb wind and rewind. Two S76 button cells for meter and shutter. Power Switch: I can't see any. The finder LED goes out by itself. Viewfinder Indications: One red LED explained under operation. Weight: 34.125 oz. (967.5g), with film, batteries and strap lugs, no strap or case, measured.