Sunday, October 27, 2013

Outdoor Flash - Beating The Sun With 2 Big Flashes

Photo #1
I made this photograph (Photo #1) of one of the four student soccer teams competing for the Mr. T Cup at the San Mateo Adult School's summer soccer tournament. While the shot isn't going to win me a Pulitzer, it does have the virtue of even lighting with great facial detail. I scouted out the playing field the day before to find a suitable background for the team shot. I chose to shoot into the sun to get more relaxed expressions on my subjects, knowing full well I would need to use flash to raise the brightness levels on the players closer to that of the open sky background.

For this shot, the "big guns" came out, namely a pair of Quantum T series flash heads connected to Norman 200B battery packs mounted on 8' light stands. They were placed about 30 degrees to the left and right of center, with the camera placed between the two stands. The flashes were triggered with a pair of Eilenchrome Skyport receivers and a camera-mounted radio transmitter. With both heads set to full power, I had a total of 400 watt-seconds between the two heads. One final note: the duration of the flash at full power, based on a table in the instruction manual, is about 1/400th of a second. 
The camera was a Nikon D7000 at ISO 100, flash white balance, with a 24-70 2.8 Nikkor set to 27mm. Instead of the D7000’s normal top flash synchronization speed of 1/250, the shutter was set to 1/200 due to the slight delay associated with radio transmitters. The aperture was set to F10, pretty much through a process of trial and error. So in a nutshell, the highest possible shutter speed would give me the darkest sky possible, and the aperture based on the output of the two flashes.

Photo #2

This closeup (Photo #2) of this player shows that the camera right flash appears to have been a bit stronger than the one on camera left, based on the shadow cast by the nose. This is because the subject is closer to the camera right flash, and therefore slightly more intense. If you look at his teammate at the opposite side (Photo #3), you'll see a change in the placement of the shadows.

In the final analysis, the shot works. The sky will be whatever brightness level (think shade of blue) the shutter speed and aperture will allow, and the aperture is based on how much flash power can be made available.