My first “pro” single-lens reflex camera was the storied Nikon F, the SLR of choice for many in the news and photography business in the 1960s.
My first “F” was a used one, purchased form a co-worker. He also sold me a 28mm wide-angle lens, a 200mm telephoto and a 50mm.
To load film in the camera, the back didn’t open. It literally came off. That was part of the design because F motor drives included a back with the motor assembly below it. A “photomic” light meter that replaced the top was also available.
The Nikon F served me well from the time I bought it in 1965 through the early 70s when I replaced it with an F2, which had the light meter built in, had a hinged back and other improvements.
Back in the film days, a new pro body would last a decade or more. Renewals didn’t come along that often. I skipped the F3 and F4 bodies entirely before buying the F5, a state of the art body in the 1990s that included better metering, a built-in motor drive, auto-focus capabilities and more.
The the D1 came along in 1999, Nikon’s first digital camera, which offered a 2.7 megapixel sensor (lord, that seems so minuscule these days) and a motor drive.
It also came with problems. The camera would just seize up or stop working all together. I replaced it twice during ownership of the D1 series. The new Canons began to show more promise in the digital field. I had a D2 when I told two Nikon camera bodies, a host of lenses and other accessories and bought a Canon EOS 1D MKII with an 8.2 megapixel sensor, a 1DS MKII with a 16 MB sensor for high resolution photographs and a several Canon lenses in 2004.
Nikon evenually caught up with Canon in the digital photo wars but, by then, I was a full-fledged Canon user and have been for 12 years now, currenly using an EOS 1D X, a 5D MKIII for stills and some video and a Canon C100 strictly for video use.