Stereo cameras were a type of camera that used two lenses to capture two separate images, which could be viewed in 3D using a special viewer. Stereo cameras were popular in the mid-20th century and were used for both personal and professional photography. Some popular stereo camera brands include Kodak, Zeiss Ikon, and Stereo Realist. While they have largely been replaced by digital 3D cameras, stereo cameras remain popular among vintage camera enthusiasts.