This paper might help you out. It is the RUS guide for the application of capacitorshttp://files.engineering.com/getfile.aspx?folder=7b875c69-2177-4080-9b47-df2f6f09cf2b&file=Application_of_Capacitors_on_Electric_System_(Excellent).pdf
I just had a sales person from SEL come in last week to discuss their Arc Flash relay.
I ask about camera flashes and he responded saying that the light threshold that the relay picks up is well above the flash from a camera. Guess testing it is the only way to find out for sure.