I am trying to set my 470ex-ai speedlite to slave mode and I can't figure out anywhere how to do so. I know that the terminology has been changed in the manual, but that being said, I still can't find anything in the manual or online that explains how to set the flash to slave mode. I know that there is a wireless triggering option but I just want the flash to fire as a result of another flash. Does anyone know how to set this?
Your Canon 470EX AI will not operate as a simple optical slave.
No Canon flash ever made can “fire as result of another flash”. There are some 3rd party flash units that can act as a simple optical slave, but not Canon.
Canon EX flash units use a proprietary optical system using coded light signals. Canon EX RT units use radio signals.
You need to use a Canon camera or flash that incorporates the Canon “Master” proprietary optical system.