It’s important, obviously, to keep the flash pointed in a direction other than straight at your subject. That way lies madness, creating flat garish lighting that eliminates texture, dimension, and any hint of shadows. The good news is that Canon and Nikon flashes today are made to sit on top of your camera, but to then be turned in other directions, up and down, side to side. The easiest way to do it is to point your flash 45 degrees backwards and over your head, as Michael Willems so often recommends. Then, the wall behind you becomes the new light source. It’s bigger and more diffuse than your flash, so it looks nicer.
Aiming your light to either side is often great, too. It creates stronger shadows and helps to define shapes better. But the simple truth of the matter is that light has a mind of its own. It wants to spray out. And while you may be pointing your flash 90 degrees to the left, some light still leaks out straight ahead, off the edge of the flash. Believe it or not, it’s plainly visible.
I noticed it last night while dying Easter eggs. I took a simple overhead shot of a plate of colored eggs. Pardon the food styling here, but it’s not the point. Let’s check out the light. The first image here shows the eggs with me standing over them, the flash pointed straight off to the left 90 degrees. Look where the specular highlight is on the egg. It’s right on top and the point closest to the camera. There’s light leaking out of the flash straight ahead. The light on the eggs looks much more direct and the whole image is flattened.
In this second image, I held my hand in front of the flash. This kept that direct light from leaking out in front, and it also warmed up some of the light as it bounced off my hand. The wall it was bouncing off of was a salmon-reddish concoction. Rust, maybe? I don’t know, but I know that color added something to the scene, as well. But note the way the light wraps more clearly around the eggs from the left. The highlights on the eggs are far off to the left now, as well. The light reflecting on the plate is not blinding or distracting. The shadows under the eggs are soft, with less rigid lines defining them. That’s not true in the previous picture, where light is scattered everywhere.
Please note: Both pics are straight out of the camera. I have not edited them in any way. I haven’t even white balanced them. I wanted to show the light, as clear and direct as possible.
Both shots were taken at 1/80th of a second with a 28mm prime lens set to f/8.0 at ISO 640.
I used my hand to flag the flash. You can also use Van Niekirk’s black foamie thingy, your hand, or something like a Rogue Flashbender. Whatever you do, try it. it’s worth it.
Additional reading: Van Niekirk has a writeup on the technique, with great picture samples.