Phillip, > Right now I only have a single 550EX to use with my 10D. I was > thinking that I might be able to get some reasonable results by using > the on camera flash to activate the 550EX off camera on its own tripod. > I have the hot shoe cord but it doesn't reach very far. > > Anyone know if the 550EX can be made to activate itself when it > detects other flashes going off? I can't find anything about that in > the manual.
The 550EX *does not* have a 'dumb' optical slave mode. There are some 3rd parties that have this feature such as the Sigma (I don't remember the model) The 550EX *can* work as a wireless E-TTL master or slave. To achieve the slave mode you're asking about, you need another 550EX as master or the ST-E2 wireless controller. This last one is just a small module that fits on the hotshoe and can control two groups of slaves. The dedicated EX macro speedlites (MR-14EX, MT24EX) can also serve as wireless master. I also have an off camera shoe cord (OCSC2) but since I got the ST-E2 I haven't used it anymore. The ST-E2 is so much flexible and you don't have the dumb cable romping on everything. You can use a peanut optical slave that can transform your 550EX into a "dumb slave" able to be triggered by the on-camera flash, but be aware that most optical slaves block after the 1st shot. I think there's a product from Wein that can do the trick (Wein digital optical slave or something alike... maybe somebody knows the right product name). I know what you're now thinking: "Why in earth Canon does not make the built-in flash a master for the E-TTL system??" ... I hope they do someday...! -regards, Gerard. * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
