Photographs, lessons learned, comments and somewhat random thoughts on photography.
Sunday, May 9, 2010
Shoot through umbrella or bounce?
I have a Wescott 43” white satin umbrella with removable black cover and have always used it in the “shoot through” style. Although “always” is the correct word, actually I've not used it that often. At the wedding of my niece, I noticed that the photographer was using two large umbrellas but in the “bounce” style. I began to wonder how my own little umbrella would do if used as a bounce surface.
Once again I called on Hannah for modeling duty -- she's so patient. Leaving the black cover on the umbrella, I set it up to bounce the light from a single SB-24 flash. The flash was about 8 feet from Hannah so the umbrella was roughly ten feet away from Hannah. The SB-24 was triggered by the RF-602 wireless trigger. After a few trial pops, I set my Canon 7D for ISO 400, manual exposure of 1/125 and f5.6. With this setup, the SB-24 could be set for ½ power and therefore recycle faster than if at full power.
Somewhere I'd read that a single RF-602 receiver could trigger two flashes: one from the hot shoe and another using a PC connecting cable. This turns out to be correct – just hook 'em up and it works! I added another SB-24 to the same RF-602 receiver, set both to ¼ power, and took another shot. As expected, the shot with two flashes at ¼ power looks about the same as the shot with one flash at ½ power. The difference is that the flashes recycle faster.
Next, the black cover was removed and the flash stand rotated 180 degrees so that the two SB-24s were shooting through the umbrella. Of course, the umbrella had to be tilted downward. The flashes were the same distance from Hannah as for the bounced shots but the umbrella was closer. Leaving the SB-24s set for ¼ power, I took another shot. To my surprise, the result was a slight overexposure, perhaps a half stop; somehow, I'd expected an underexposure. At that point, I noticed that the SB-24s were set to match a 35mm focal length; that is, slightly zoomed in. I zoomed out to the maximum of 24mm and took another shot. This last shot was not quite so overexposed.
Later, using Photoshop to process the RAW files, I estimated that, for the way I did it, the shoot through method gained about a quarter of a stop of flash power. Had I first shot using the shoot through umbrella, I know I'd have adjusted the exposure downward by about a half stop based on chimping the 7D LCD. As it turns out, the resulting exposure would have been a little underexposed.
Aside from exposure, what were the differences between shoot through and bounce? Well, just look at the two shots of Hannah. Oh, the one on the left was taken using bounce and the shot on the right was taken using shoot through. Both were processed from RAW using identical ACR settings except for exposure. There is a slight difference in color although the white balance was identical in ACR. It seems to me that the picture using shoot through is slightly more softly lit. I think I'll be staying with the shoot through style.