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miles747
28th of August 2004 (Sat), 08:02
I have set up my Canon 10D with a master 550EX and one slave 550EX. I have successfully tested the slave in my home and outside on a wooden deck. However, when I attempt to use the master / slave configuration in a 75 year old stone church with a very high ceiling and stone floor, the slave unit fires approximately 10% of the time (both when shooting actual photos or just pressing the test button on the master). I am using new batteries in both flashes, recharged battery in the camera and have tried both channel 1 and channel 4 in the master and slave units. I also swapped the master unit to the slave and the slave to the master with no change in the results. Master to slave distance is less than the recommended 8 meters. As a side note, I encounter this same problem when shooting outdoors (on stone steps) in front of this church. Any suggestions on what I am doing wrong.

robertwgross
28th of August 2004 (Sat), 12:25
Master to slave distance of 8 meters?

How are the master and slave units oriented with respect to each other?

On the master 550EX, the red lens beneath the main flash head has to be aimed at the slave 550EX, or else there must be some reflective surface in the scene that will bounce the data signal to the slave. Stone surfaces are not very reflective, I believe.

---Bob Gross---