The Canon EOS (Electro-Optical System) autofocus 35 mm film an digital SLR camera system was introduced in 1987 with the Canon EOS 650 and is still in production as Canon's current dSLR system. The acronym EOS was chosen for Eos, the Titan Goddess of dawn in Greek mythology, and is often pronounced as a word, although some spell out the letters. There is no officially correct way, as both ways mean something logical.