550EX Slave Flash

[jasonco]

Can anyone tell me if this is possible?

Canon EOS 10D with infrared slave trigger on hot shoe flash mount.

Studio light with slave sensor (this bit works fine)

Canon Speedlite 550EX mounted on tripod.


Would the infrared flash trigger also trigger the 550EX in slave mode?

Cheers
Jason

[DaveG]

jasonco wrote:
Can anyone tell me if this is possible?

Canon EOS 10D with infrared slave trigger on hot shoe flash mount.

Studio light with slave sensor (this bit works fine)

Canon Speedlite 550EX mounted on tripod.


Would the infrared flash trigger also trigger the 550EX in slave mode?

Cheers
Jason

Do you mean the Canon ST-E2 transmitter when you say "infrared slave trigger"? If it's not the ST-E2 or another 550EX flash then it won't trigger your 550EX mounted on the tripod.

If you were using the ST-E2/550EX and wanted to get Wireless TTL lighting ratios it will not trigger the studio light slave.

Here's what you'd need to do. If you have a non Canon infrared flash trigger you'd have to add an optical slave to the 550. The 550 would have to be on one of the manual settings. This dumbs down the capability of the 550 but at least it would work.

If you go the other way with the Canon Wireless TTL you can't use the studio stobe at all. The Canon Wireless TTL works only with the E-TTL system and that sends out a weak flash pulse just before the real flash fires. That first pulse has coded information that tells the outboard 550/420 flash how to out put. But that first pulse will also set off any light slaved flash. Your studio strobe WOULD fire but it would fire an nth of a second too quickly and couldn't possibly recycle quickly enough to give you flash output for the "real" exposure.

This E-TTL system also precludes the use of a flash meter since - once again - the flash meter will read the first weak light pulse, not the operative one. Of course with the 550 on a manual setting the slaved studio strobe and the flash meter will work just fine.

[jasonco]

Thankyou very much for the detailed reply. I will try this out and let you know how it goes!

Cheers
Jason