For instance, the Canon EOS Digital Rebel XT. EOS is Canon's copyright for an Auto Focus SLR camera lens system. They couldn't copyright "Auto Focus" so they chose Electro-Optical System. EOS dates back to the first auto focus SLR film camera line Canon produced back in the late 1980's. And since all the lenses from back then will still work on today's Canon DSLR cameras they still include the EOS badge.
If Canon ever does design a new lens system they will probably come up with a new term to copyright. But the EOS line celebrates 20 years this year, and is still going strong so I don't think it will be replaced soon. Electro-Optical System. It's more a brand name type thing than some special feature. | 