The approach was relatively simple: Stand on a step ladder while holding a Nikon D600 with a Nikkor 2.8 24-70mm lens. A Norman 800D flash was used with a 12 foot tall light stand just to my right. I had enough light from this monster flash to shoot at 1/200th of a second, F 13.0, and an ISO of 125. Slam Dunk.
How could this be? I was using a Norman 800D powerpack with a single flash head had plenty of power, but apparently not enough to reach back to the last rows of well-wishers. Put simply, I was caught by a simple maxim: The greater the distance from the light source to the subject, the less intense the illumination.
Layers To The Rescue: In an effort to brighten up my most distant subjects, I used the Layers command to create two duplicates of my original image. When the layers are created, they will be perfectly aligned, one on top of the other. Each layer can be manipulated individually.On the topmost duplicate, I did the following:
- Adjusted the exposure to a more "natural" level, and
- Erased all of the students who were now too bright as a result of the adjustment (Photo #3).
Close Enough For Jazz: Careful examination of the background subjects shows a lack of contrast between the highlight and shadow areas. I believe the explanation lies in the relative weakness of the flash illumination when it travels to those faces in the back. In reality, the light hitting the farthest faces isn't that much brighter than the ambient light, so there is less shadow-to-highlight contrast. Boosting the brightness brings the tonal levels closer, but the "snap" seen in the front row is lost. I suspect that all such exposure manipulations will display this tell-tale lack of contrast, but under the circumstances, the overall quality of the final image was much more than I had a right to expect.