Off-Camera Speedlite Setup for Canon...

When putting together a kit for off-camera flash with my Canon 20D I found I had to pull information from several different places to understand connections, compatibility and limitations so I wanted to put the final result down on paper in case anyone else is in the same boat...

As an amateur photographer, if someone asked me what distinguishes a professional photographer’s work from the rest of us, my top two answers would be a trained eye for composition and knowing how to use lighting for effect.  Without a strong composition a photo will not convey an intended meaning or feeling.  Lighting is a part of composition that will not make a photo great by itself, but often distinguishes a really terrific photo from an average photo.  In landscape photography we often hear of the “golden hour” - one hour after sunrise and before sunset - where warm colours in the sky or long shadows provide strong impact to photos.  

Until recently, I used a speedlite for some indoor shots and macro (ETTL only), and thought that great lighting came from either natural lighting under the right conditions or in a studio where lighting would be incredibly complicated, expensive and not at all portable - enter Strobist.

Thanks to David Hobby, I learned that amazing lighting can be generated using only small speedlites.  Relative to the investment in good lenses, a couple good flashes, stands and umbrellas is quite inexpensive and can dramatically improve picture quality.  When I decided to put together a small off-camera lighting kit I wanted it to meet three criteria:

1. I wanted to be able to use Canon ETTL with my flashes under some conditions.  I am a macro shooter and ETTL allows quick adaptability that might not be possible with manual flash settings.  I have a MT-24EX and plan to add a ST-E2 to my bag for firing Canon wireless ETTL flashes.
   
2. I am interested in high-speed flash photography, using speedlites set to low manual power.  For this reason I wanted to be able to trigger them manually with trigger kits such as those available at www.hiviz.com.  Some applications are too fast to use the Canon wireless to fire the flashes so synch cords are essential.
   
3. If I should purchase radio triggers down the road (Pocket Wizard or Radio Popper), I would like my flashes to already be compatible with them.

Based on these criteria, I purchased a Canon 580EX and 430EX, which are each capable of manual control, and manual flash head zoom.  In order to fire them manually with both speedlites off-camera or using a trigger kit, I also purchased two Paramount hotshoe-to-miniplug (3.5mm) adapters and a pc-to-miniplug cord.  I happened to have some stereo miniphone cables and a mini-phone Y-cord to use as an improvised synch cord.    The high-speed trigger circuits are easily adapted to connect to the flash with a mini-phone plug.  This allows me to cover all the shooting scenarios above, for a minimal setup cost, and my setup is ready for radio triggers at any time in the future.  Now I have the best of both worlds... full ETTL or manual as I need them.

Speedlite flashes fire by shorting a trigger circuit, and on some older flashes the trigger circuit is very high voltage, which can damage newer digital cameras.  This can easily be measured using a multimeter.  Canon's newer cameras are limited to 5V trigger circuits.  On the Canon speedlites, the center pin on the base is +5V, and the rail contact (hidden on the top side of the hotshoe) is ground.  As an added bonus, the 430EX can be fired wirelessly by the 580EX, when the 580EX is fired using a synch cable.  This means you only need a synch cable to one flash (or one set of pocket wizards) to fire two flashes  - as long as the two flashes are close enough together.  A couple limitations that I’ve found when firing flashes manually are:

1. When the MT-24EX is fired using the pc cable with hotshoe adapter it will not fire a slave flash set to manual power.
   
2. When the 580EX is fired using the pc cable it will fire the 430EX in slave mode wirelessly, but the max synch speed is limited to 1/160.  This is presumably due to the time required for the master to communicate with the slave.
3. From what I've read (but have no firsthand experience) the newer Canon 580EX II, which has a PC connection, will not fire a wireless slave if fired from the PC jack.  The workaround for this is to fire it using a PC to hotshoe adapter.
4. When firing the flashes using the high-speed kits a silicon controlled rectifier acts as a switch to short the trigger circuit.  The Canon trigger circuits have some residual current flow that won't allow the SCR to reset after it fires, making the flash seem to freeze after one flash.  A solution that worked for me was placing a resistor in series with the SCR, thus allowing the SCR to reset - it took some trial and error to find the right resistance.  Similar problems have been encountered by some people using various types of wireless triggers on their Canon speedlites presumably because they also use an SCR to trigger the flash.

It's also worth mentioning that there is a more elegant solution to connect Canon speedlites to synch cables or Pocket Wizards than what I've done.  Michael Bass has been modifying flashes with sub-minijacks instead of using a hotshoe adapter or the crippled PC jack on the 580EX II.  This allows you to plug a sub-miniphone cord (2.5mm) right into the flash - cool!

If you have any questions or comments, (or see any errors) please drop me a line.  In later posts I'll talk about using high-speed kits to fire the camera, modifying my RS-80N3 and building an extension cable and trigger switch for my RS-80N3.

Cheers, Brad