Scott, photographers, especially those who have earned their living with it, tend to be very brand loyal. In 1974, the DOD combined the Army and Air Force photography schools and closed the Army photo school and moved the Army to the Air Force school in Denver. The Army's standard 35mm camera at the time was the Canon F1. The Air Force and Marines used the Nikon F2 (the Marines sent their photographers to the Air Force photo school instead of the Navy photo school as the Air Force school was better). We trained Saudi, Iranian, Jordanian, and Nigerian Air Force students. They all used the Nikon. We instructors had to teach both. Interesting thing about it was that when the students processed the film and made 8x10 prints no one could tell which was a Nikon or Canon photo.
In the Korean war era, photographers generally used Leica cameras. A famous photojournalist and LIFE Magazine photographer, David Douglas Duncan, had his Leicas stolen. A Japanese camera store loaned him Nikon gear and he took it to Korea. The editors at LIFE asked him what he was shooting with as the images were so sharp. He is a hero to Nikon as they give him credit for giving them their big start.