Nikon's introduction of its Z6 and Z7 cameras might make it the most recent company to hop on board the professional mirrorless-camera bandwagon, but the venerable Japanese firm is hardly the first to take a crack at cutting the flipping mirror of single-lens-reflex cameras out of the optical path.

Olympus and Panasonic were some of the pioneers of the digital mirrorless camera with the Four Thirds and Micro Four Thirds systems. Fujifilm's X System and Sony's Alpha family of cameras are some of the most popular mirror-free picture-takers available today. Why is the industry making the mirror persona non grata, though? Let's take a little trip into the history books.