I am reasonably new to flash photography and have a 7D with 2 580ex II flash units. Am I naive to think that I can use these units powered and triggered with the 7D's pop up flash head?
My results are absolutely hit and miss so far. Sometimes the flash will go off and most of the tiime if it works every other or third time I feel lucky. Also the remote flash(s) constantly turn off, which is very frustrating.
Would I have better luck using one of the 580's as the master instead of the pop up head?
In a typically-sized home setting with light-toned walls the pop-up's light will bounce around enough to reach the sensors on the slave flashes, even when they're inside softboxes or other modifiers. Outdoors, or in large/dark spaces, it won't work as reliably...if at all.
Using one of the 580EXes as a Master will give you more power and the ability to aim the Master's head at at least one Slave, which can help.
As for the Slaves turning off, check you User's Guide for how to disable the Automatic Sleep mode with your particualr model of flash.
BTW, by way of example here is a portrait I made using my 7D's pop-up as the Master, and triggering a 580EX II Slave in a 28-inch Apollo softbox to camera right, and a 430EX II on a boom firing through a 12-inch gridded dish as a hair light:
The most important factor in getting maximum reliability is to make sure the sensors on the Slave flashes are turned to face the Master (or to face the direction that the Master's light will be bouncing from), and that the sensors are not obstructed by light stands, large cables, etc.
Jred wrote:
Thanks Brian. Seems like a risky proposition at best. Any thoughts on other more reliable ETTL solutions?
I sometimes use a 24-foot ETTL cable to connect my camera and one 580EX set to Master, and use it to trigger the Slave(s), but there are still issues with the Slaves seeing the Master's pulses in some cases. It works great under the right conditions, though.
The most reliable method is radio triggers, but if you want ETTL rather than Manual-only you're talking a pretty serious investment.
I was on the brink of buying a Phottix Odin transmitter and some receivers, but I cancelled the order when I heard that Canon was releasing the new Speedlite 600EX-RT that has built-in radio triggering, plus the new ST-E3-RT Controller.
Since my existing Speedlites won't work with the new ones in ETTL-Radio mode, moving up would be expensive, but I might do it in a year or two.
Your comment that the remote flashes are constantly turning off would seem to indicate you are not setting them correctly in slave mode. In slave mode they should stay active with the red AF assist light blinking as a "ready" light.
As BrianO mentioned the critical factor is the slave sensor (the small gray lens on the front of the base) seeing the light from the Master. Indoors it can be bounced off walls and ceilings, but outdoors you need line of sight.
The Canon optical system is only as good as the footprint and range of the Master flash. While the pop-up flash of the 7D will trigger the remote flashes you'll get more reliable signalling if instead you use one of your 580exII units connected to the hot shoe as Master and the other as Slave because the 580exII has greater range and a larger footprint. I've used my 580ex flashes that way for going on 8 years now without finding I needed radio triggers. If you click the WWW button below it will link you to my Canon flash tutorials.
