I graduated from high school in 1965. At the time, only seniors' pictures were put in the yearbook, and a photography studio had the contract, so everyone who had a portrait sitting was in the class of '65. As I remember, he made several proofs (on a reddish proof paper). The photographer delivered the appropriate prints to the yearbook staff, who put them in a page layout, and sent that off to the printing company. The studio used a 4x5 portrait camera (don't remember the make or model).
My mom and dad selected a "package" of wallet, 5x7, 8x10, etc. photos touched up (lots of zits edited out).