Additionally, the mass production of photographs made it possible to sell them at low prices to almost any collector. Nude male photography surged as everyone from fashion photographers like George Platt Lynes to underground artists like Al Urban, Douglas of Detroit and Bruce of L.A. Today, male nude photography is so readily available that the Kinsey Institute has stopped collecting it.
Most of the vintage gay porn I have is from the 1950s onward.
Which is to say, most of the readily available vintage gay porn.