Wednesday, December 12, 2007
G9 with Canon External Flash
Having a hotshoe for external flash is a great feature of the Canon G9. The G9 works well with Canon’s recent flashes and even some of the older ones. Just be aware that the G9 is small in comparison to some of these external flashes so the combination can be somewhat unwieldy. Also, the flash can cost almost as much as the G9! Here are some simplistic examples using the Canon 580EX on the G9.
Imagine that you come upon Woof-Woof in his favorite chair. Naturally, your G9 is in your hand and you quickly get the above shot using Program mode and ISO 80. The G9, being in Program mode with flash turned off, selected an exposure of 1/60 second at f3.2. As a result, the bright outdoor scene is overexposed and the indoor scene is underexposed. Flash is needed to bring up the interior lighting level. But if you use the built-in G9 flash, you can be certain of creating red-eye in poor Woof-Woof. You grab that big, expensive 580EX, fasten it to the G9 hotshoe and fire off another shoe before Woof-Woof knows what’s happening.
For this second shot, shown above, the G9, still in Program Mode but knowing that a Canon ETTL flash is in the hotshoe, again selected an exposure of 1/60 and f3.2. This is somewhat better but now it looks like a “flash” picture. Notice that the bright outdoor scene is still overexposed because the shutter speed and aperture have not changed. Determined, you remember about bounce flash, rotate the 580EX flash head towards the white ceiling and grab another shot.
Still in Program Mode, the G9 is convinced that 1/60 and f3.2 is the correct exposure; however, bouncing has softened the flash considerably as shown in the above photo. The outdoor scene is still overexposed. Suddenly you remember that a correct exposure for bright outdoors is given by the Sunny 16 rule as modified for the G9. Pretending to shoot the outdoor scene (only) through the window, sure enough: 1/500 and f5.6 is about right. You change the G9 to Manual Mode, set shutter speed to 1/500 and aperture to f5.6 and fire off a shot.
Finally, the indoor and outdoor scenes are properly exposed. Good dog, Woof-Woof!
Later you notice something odd: That last shot was not actually taken at 1/500 and f5.6 even though you know that those were the settings on the G9. That last shot was actually taken at 1/250 and f5.6. Checking the histogram, the outdoors is a little overexposed and the sky has a few blinking highlights. How could this have happened?
In Manual Mode with a Canon ETTL flash attached, the G9 will not allow shutter speeds faster than 1/250 second. If you set a faster shutter speed in Manual Mode, the speed will be reset to 1/250 when the shutter button is pressed. In fact, even if you turn the ETTL feature off, the G9 will reset from 1/500 to 1/250 shutter speed.
Even worse, ETTL was not in control of the 580EX when that last picture was taken. It was a fortunate coincidence that full 580EX power bounced from the ceiling was about right. ETTL flash control does not work when the Canon G9 is in Manual Mode. The output power of a Canon flash mounted on the G9 must be adjusted either on the G9 or on the flash when the G9 is in Manual Mode. I don’t like it but that’s the way it is -- same on all the G series cameras.
(Note: All pictures above were downsized from the unprocessed in-camera jpg for consistency. Some prefer a slightly overexposed outdoor view to preserve the effect. See the Strobist blog for many more variations on this idea.)