firing slaves with popup flash

<p>I've got a 30D, a Speedlight and a Metz flash. Can I fire the Speedlight and the Mets with the popup flash on the 30D?</p>

<p>If so, how do I set up the popup flash to trigger the two slaves?</p>

<p>Hi Emily,<br>

You'll have to attach a <a href="http://www.adorama.com/catalog.tpl?op=itemlist&cat1=Flash/Lighting&cat2=Slaves&cat3=Flash%20Activated%20Slaves">Flash Activated Slave</a> to each of the flash units; these can be had for as little as $20 or so. Or you can use both flash units with a single slave and a Y connector (paramountcords.com). I think with digital there may be a need to use a compatible slave, but I'm not sure about this. Hope this helps.</p>

<p>No, because the pop up flash cannot be controlled manually and ETTL, which has a pre flash and is what the pop up uses, will prematurely fire the off camera flashes when using an optical slave. Even using the Canon wireless system (assuming your speedlight is an EX flash capable of participating in the system), the pop up cannot be used.</p>

<p>Hi Emily-</p>

<p>I just went through this the other day when trying to use a friends Nikon SB-800 as an off-camera flash with my Canon 50D. It was the only flash I had available at the time, and I didn't have access to any sort of PC or sync cables. This was my experience on a 50D, hopefully it transfers to the 30D:</p>

<p>As Steven said, each flash needs to be able to fire as a slave when it detects a flash. Some speedlights have this built in as a feature, check your manual. For example on an SB-800, in the settings menu you can select SU-4 mode, then hit the "mode" button to put it into manual mode. (see instructions <a href="http://strobist.blogspot.com/2007/08/unlock-superslave-in-your-nikon-sb-800.html">here</a> ).</p>

<p>As Nadine pointed out, the pop up flash ETTL pre-flash causes problems. The external flashes will fire upon seeing this pre-flash (about 1/20th of a second before the shutter opens), and will be busy recycling once the shutter opens and the actual flash fire occurs. One way around this is to use your AE Lock (the * button) to pre-meter the scene. This will cause the ETTL pre-flash to fire, which in turn will in turn cause your external flashes to fire. Continue holding the AE Lock button down until your external flashes recycle, then press the shutter button. Now your main flash should trigger your external flashes with the shutter open.</p>

<p>If you don't want the scene to be illuminated by your pop-up flash, turn the flash exposure compensation down as low as it will go. Depending on the power of the external flashes and the camera settings, you may or may not notice the pop-up flash's light in the scene. You can use an index card to block/diffuse this light even more.</p>

<p>Also, be careful of using auto focus in dimly lit situations with your pop-up flash. If your camera is set to use an AF-assist beam, quick strobes will be emitted from your pop-up flash to aid in focusing when you press the shutter button. This strobe will also cause the external flashes to fire before the shutter opens. You can get around this in low light situations by disabling the AF-assist beam in the camera's menus or by using manual focus.</p>