According to this article, Walt Schirra's Hasselblad was the first one in space and after that they were used exclusively for some years. I guess before that they were custom.
The first camera that was brought into space for the Mercury program was a remarkably unremarkable Ansco Autoset rangefinder manufactured by Minolta [1] that was picked up at a drug store, which went up with John Glenn.
Of course, Hasselblad didn't put that in their marketing material. Nasa then moved to using Nikon cameras around the Spacelab era, and still uses Nikons to this day.
So far NASA used Nikon because Nikon didn't use fluorite elements, unlike Canon. However now Nikon started to use fluorite elements as well. I wonder what will happen in the future.
Fluorite glass is more sensitive to shock and vibration compared to regular optical glasses. Iirc some people actually managed to disintegrate lens elements here on earth, without even hurling them into space.
I guess that makes sense but is NASA actually shipping off the shelf DSLR lenses to space anyway? I guess for astronauts’ personal devices, whatever. But for actual scientific instruments, I’d expect NASA is bidding out custom contracts that can easily specify how much shock tolerance the cameras must withstand.
https://www.hasselblad.com/history/hasselblad-in-space/