The Nikonos IVa and V battery compartment.

O.K., we all know there's a battery in there. Most folks try to ignore this part of their camera. It has an o-ring and is made of metal and plastic, is screwed through metal, into metal threads, where it centers onto a spring contact.

So what's the problem?
It's all held together by a plastic cap-shaped part and two little screws. If the plastic cracks, in blows your battery compartment (underwater) and your camera gets wet.

There are two sides to the problem: if you clean the o-ring dive-daily, you must open the compartment and stress the plastic part when you reinstall. If you don't, you risk camera damage from a contaminated o-ring allowing water past the seat into the battery compartment. This o-ring salts up faster than most others, but I won't lecture...
Use a nickel to unscrew the battery compartment. Clean and reinstall the o-ring as close to once every dive day as possible. If you put a light film of grease on the seat, (that is the part of the camera the o-ring comes in contact with), it will ease the subsequent removal and reinstallation of the battery compartment.

Hold the camera right side up to install the battery compartment. (Upside down puts stress on the plastic compartment.) Push the compartment in as far as you can and then put the nickel in the slot and push up (holding the camera upright still). Turn the nickel counter-clockwise until you hear a click, then turn clockwise until seated. Turning counter-clockwise first helps properly start the threads. If it feels tight or looks crooked, stop and start over.

A little extra grease on the part of the camera that the port screws into is helpful, especially on the old-style Nikonos V (black hole). The new-style has a silver hole.

Call with questions (831) 484-6230 Dan Blodget

Remember: lightly greased o-rings are slick like a trout. Over-greasing isn't helpful.