Nikon Nikonos IV-A

Twenty meters down on a reef wall, the diver has one hand on the camera and one on a strobe arm, and the body in that hand is shrugging off the water pressure like it isn't there. No housing. The Nikonos IV-A is the camera itself sealed against the sea, o-rings doing the work a plastic case does on every other system. You load it on the boat, drop in, and shoot. That was the whole pitch, and for a couple of decades it defined the sealed-body approach to underwater photography.

The IV-A added aperture priority to the Nikonos line, which is the part people either loved or distrusted. You set the lens aperture, the center-weighted meter picks the shutter speed, and an LED in the finder confirms the auto-chosen speed sits in the usable range. When it doesn't, the same light warns you off, over or under. There is no needle to read and no scale to interpret. The focal-plane shutter runs from long exposures down to about 1/1000, with flash sync at 1/90. The viewfinder is bright but bare. No rangefinder patch, no ground glass. You guess distance, set it on the lens by feel or by the depth-of-field scale, and trust the small apertures to cover your error. Underwater, where everything is closer than it looks, that scale-focus habit becomes second nature or it ruins your frames.

Build is the reason these survive. The body is dense, the controls are oversized for gloved fingers, and the few buttons move with a positive, unmistakable click. It runs on batteries for the meter, and that is the first honest weakness. Lose power and the IV-A gives you only the mechanical sync speed near 1/90, so a dead cell on a dive trip turns an automatic camera into a one-speed one. The second weakness is the o-rings themselves. Skip greasing them, trap a hair in the seal, and you flood the camera. Every Nikonos owner has a flood story or knows someone who does.

On land it works fine, and plenty of people shot the IV-A as a foul-weather street and travel camera precisely because rain and sand mean nothing to it. The wide Nikonos lenses are sharp, and the whole rig is small enough to swing one-handed. Today it sits in the affordable-cult tier. Divers cross-shop it against the later Nikonos V, which most people prefer because its readout shows the actual selected shutter speed rather than the IV-A's simpler in-range or out-of-range LED. So the IV-A often goes cheaper while doing nearly the same job.

For the scale-focus, no-rangefinder reality of this body, a reading off the Zone Light Meter app before you descend is worth more than the in-finder LED. Surface light and depth-filtered light are different animals, so place your shadows from a known incident reading at the top, then let the aperture-priority meter trim from there. People buy these because the trade still makes sense. You take pictures in places that would kill a normal camera, and the camera keeps shooting.