annual service necessary?

I dive my Nikonos 5 a couple times a year. I clean it well and remove the O rings between dives.

I have three lenses, two bodies, and two strobes. Does anybody know if the annual O ring and pressure test is necessary. That's alot of money.

It depends on how well you maintain your gear. When I used mine all the time, I had two bodies and serviced them in alternating years. Storage in a dry environment, and sand and salt can play havoc with the internal orings. Soak all gear in warm fresh water after every use, rotate all the knobs, clean off any excess grease. I have only serviced one lens: the 15mm. I also only serviced one strobe ever. I stopped when I realized Nikon Canada was charging more than I can buy a new SB 105 for on EBay. I have found Underwater Photo Tech very reasonable for service costs, although a bit slow. Servicing is certainly cheaper than replacement.

Go to sothern-nikonos.com.All the info you need and then some.Print it all off and take it with you when you are away.