Original: The acronym EOS was chosen for Eos , the Titan Goddess of dawn in Greek mythology , and is often pronounced as a word ( i.e. , EE-oss ) , although some spell out the letters , reading it as an initialism .
Simplified: The Canon EOS ( Electro-Optical System ) is an autofocus 35 mm film and digital SLR camera system that was introduced in 1987 with the Canon EOS 650 and is still in production as Canons current dSLR system .