my friend asked me to shoot as a backup for his wedding. i'm using a 20D with 28-75L and a sigma ef dg 500 super. it was a bright and sunny day and i was shooting a group of people at f22 from 15 ft away. the flash didn't help a bit with the fill, and i notice in some of the pictures, there were harsh shadows. what is the recommended settings on a 20d for using fill flash outdoors.
Why did you shoot at F/22? Ho much of a difference in Depth of Field are you going to get if you were shooting F/16? Or even F/8? If you were shooting back up how big do you think the print of this group shot is going to be?
What ISO were you shooting? I think it comes down to you asking a lot of your little flash. What was your shooting distance? I don't think that there are many flashes that came do that. If you want to shoot at F/22 for group shots why not invest a little money on some strobes.
Get the subjects under some open shade, get a dark background (tree, whatever). Put your iso as low as possible, the idea is you want to open your aperture more, hopefully f/8. That's why wedding shooters like high sync speed!
At f/22, practically none of the flash light made it to the sensor. Why the heck were you shooting so stopped down from 15 feet away? If you'd have shot at f/5.6 or so, the fill flash would probably have worked just fine, but at f/22, you'd have needed about 4 flashguns from that distance to make any difference.
It sounds like you may have either left your camera mode on tv or p and the meter stopped down to maximum aperture to compensate or you were overly concerned about your depth of field. Unless your group is more than three or four rows deep, f/8 should be plenty. You definitely want control of aperture and, ideally, speed as well.
Try this next time. Set camera manual at f/8. Because your ambient light is already very strong, the 20D's flash should automatically enter into fill flash mode (I think -1.5 EV). This won't eliminate strong shadows (look for shady spot) but it should give you the fill you want.
