cgardner
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As stated, you can't use ETTL mode on the flash with PWII. For ETTL you need a Canon master flash (5x0ex) in the hotshoe or connected to the hotshoe via the OC-E3 cord. The master flash communicates with the Canon slaves via coded pre-flash pulses.
With your PWIIs both camera and flash need to be in M mode. You don't state what flashes you are using. If 580ex or 430ex you'll need to put the wireless switch in "SLAVE" position, then press the mode button for 2 sec. which will put the flash in "Dumb" slave mode where it will not go to sleep.
Setting ratio is a matter of power and distance. For any given power setting on the flash the highlights will only be exposed correctly at X ft. from the flash. Put your camera on f/8, a single flash on 1/2 power with the flash zoom set manually to 50mm and shoot a scene with a white towel in it from various distances. Some distances will over-expose the towel (i.e. you'll see a clipping warning). Find the distance where the clipping warning disappears you'll have a baseline exposure ( f/8 @ 1/2 power @ X feet) you can use to calculate exposure at any other f/stop of distance.
Shooting with two flashes works the same way. Back in the 1970s when shooting wedding receptions with single power manual flash we'd use fill on the flash bracket then adjust the distance of off camera flash, and the aperture of the camera, as the shooting distance changed. The key to making it work was being systematic.
If shooting at a distance of 11ft the off camera flash would be placed at 8ft, which per inverse-square makes it 2x brighter than fill (incident) resulting in a 3:1 reflected ratio when key overlaps fill ( 2k+1f: 1f) = 3:1. A simple, one-time exposure bracket test established the f/stop need for the two lights at those distances. It didn't matter where the off camera flash was placed (in front for short lighting, behind for rim lighting) if it was kept at a distance of 8ft the exposure and ratio would be contant and so would the exposure. That's the beauty of manual flash once you get the hang of it and work systematically, it is consistent and VERY predictable.
If the shooting distance changed to 8ft two things would happen: first the off camera flash would be moved to 6ft to maintain the same light ratio, then the aperture of the camera would be reduced by a stop to compensate for the fact both lights were closer to keep the exposure the same. Move in to 6ft and the key light moves to 4ft and the aperture is reduced another stop.
By using that systematic method -- devised by Monte Zucker who I was working for at the time -- an entire wedding reception could be covered by using 16ft/11ft; 11ft/8ft; 8ft/6ft camera position/key light distance with a 3 stop range of aperture adjustment. It was very simple, and predictable.
I still use the same technique when shooting portraits with my pair of Canon 580ex. I use M rather than ETT for consistency shot-to-shot. Off camera flash at 1/2 power w. DIY diffuser, placed 5.5ft from the nose of the subject (one arm span - easy to measure consistently). Then I take four measured steps backwards to shoot (to 8ft) with fill at 1/2 power w. diffuser on my bracket, and shoot at f/8 (determined by a one-time test). I can set up and be shooting in 2-3min. and shoot dozens of people production line style and get consistent results shot-to-shot.
For a dynamic situation like sports where your flash/subject and camera/subject distance is constantly changing ETTL wireless ratios is a much better strategy because it will automatically adapt to difference in distance one you establish correct exposure level with an overall FEC adjustment.
The Canon optical system works well out to a distance of 40+ feet indoors and 25+ feet outdoors, but you need to be aware of a few design constraints: the sensor on the slave which is the small gray lens on the front can't be blocked or blinded by direct sun and needs to be oriented toward the light of the Master. There's no IR if a 580ex is used as Master, and direct line of sight is not needed, the slave simply needs to see the pre-flashes of the Master with sufficient intensity. You can test if the slave can see the master by pressing the pilot lamp on the master, which will flash immediately, with the slave answering with a single flash about 1 sec. later.
For distances beyond the range of the built-in visible coded signaling, or where interference from sunlight is a problem, you'll need to add RadioPoppers or the newer PW. Of the two I think the RPs are superior because they just relay the Canon signals: there is no new user interface to learn, you just pop them on and they work. The new PW units mimic the function of the Master controller which requires a somewhat more complicated set-up routine and a different mode of operation from the Canon wireless system.
One workaround to get the benefits of mixing Canon and manual flash is to use your Canon 580ex as master in the hot shoe to command the Canon slaves, and also connect your PW triggered manual flashes to the PC connector of the camera. When you press the shutter the Canons will do their pre-flash set-up routine, then the main flash from the Canons and the PC socket triggered manual flashes will occur at the same time in perfect sync. One caveat is that because the camera will not see the manual triggered flash is using ETTL mode which involves in-camera metering any overlap of manual and Canon ETTL flash will result in over exposure. So its best to either use the manual flash for things like background light or rim lighting from the back, or use the Canon flashes in wireless M mode.
Chuck
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