On Camera Fill Flash

On camera flash is generally not considered to be the most flattering light source - especially when photographing people. There are times however when on camera flash can make a big difference in an image.

Many photographers love to use available light because it can create a very beautiful light on your subject.  Sometimes however, the light can be very contrasty, creating detailless shadows on the shadow side of your subject.  The natural reaction is to find some sort of reflector to fill light in to the shadow side.  Well here is another possible solution that when executed well, will give you excellent results.

It is well known that a soft, wrap around light source, needs to be large relative to the subject.  the problem with a speedlight or on camera flash is that it is a very small light source, which will create a very harsh or hard light. When handled properly though, this is OK for fill light. Lets see how that works out.



Figure 1

Take a look at this image. It is a Styrofoam ball photographed with a speedlight inside of a 2 ft soft box. Most definitely a soft light source or this object. Notice that the ball is virtually shadowless except for a little around the edges (this is because the object is round), making it an excellent fill light.
Why is this an excellent fill light?  The purpose of a fill light is to reduce the contrast in an image. A fill light should bring the exposure level up in the shadow side of your subject. Most of the time because you want to have detail in the shadows. a good fill light will create no shadow of its own. If it does, you can start to get very unnatural looking double shadows on your subject. A soft box (or any other larger light modifier) is one way to help prevent this from happening. Another is placement of the fill light.

A light source that is on the same axis as your lens will not produce a shadow that your lens can see. In figure one, the light source was place as close to the lens axis as it could be without putting the camera directly in front of the light source. This further helped to create the shadowless lighting.



Figure 2

 Now take a look at figure 2.This was taken with a bare speedlight or flash. Even though it is a hard light source, it created a shadowless light on the Styrofoam ball. To achieve this shadowless light, the flash was also place as close to the camera axis as possible without having the camera in front of it. The fact that the two light sources created a nearly identical light can be put to use.

Consider the next time you are out creating a portrait and you have very contrasty light. Instead of grabbing a reflector, try using a flash to fill in the shadows. Here's how you can do it. Determine the exposure of your subject so that you get detail in the highlights. Put your flash as close to the camera axis as you can - this will usually be on the hot shoe. With your flash on E-TTL or I-TTL if you use Nikon, set the flash exposure compensation around -1.5 to -2. Take your image then readjust exposure to achieve the results you want.

Here are a couple of pitfalls to watch for

1. Do not overpower the flash. this will create an unflattering, flashed looking image.
2. Keep the flash above the camera, even if it means always shooting horizontally then cropping to vertical later. Because the flash will not be exactly on axis, it will create some shadow and it looks more natural when it is going downward.
3. Have your subject far enough from the background so that any shadow will fall behind the subject and not show up on the background.

Go out and have fun with this technique. Once you master it you'll love it.