Fill light softbox size

<p>Should the softbox on a fill light be the same size as the one used on my main light? (I'm thinking about a 24" x 32" softbox for my main light—probably as big as I can go.)</p>

<p>The fill light can be literally anything other than a very restrictive light such as a honeycomb grid or a spotlight, it's function is to illuminate all of the subject as seen by the lens, and as its position is immediately above or immediately below the lens (or behind it) it is usually so far away from the subject that the size doesn't make a great deal of difference</p>

<p>Craig,</p>

<p>I'll give you a different take on this. As Gary says, the function is to illuminate all of the subject. No argument there. It's exposure function is simply to raise the basic illumination level on the subject enough to see detail but to avoid creating shadows. As such, the smaller the source, the bigger the chance of creating shadow as smaller sizes used farther away approach creating a focused form of light which can easily create shadows (the job of the main light). Using a very large soft box or umbrella, or even bouncing off the back wall, if it is white, can all be effective ways of creating good basic fill illumination. Using a fill at least the same size as the main is essential.</p>

<p>Another thing to consider is the fill position. Fill position is often assumed to be right at the axis of the camera lens and that works on some commercial applications and still life work. But, for portraiture, it can be dead wrong and create secondary and very distracting shadows, especially from the projecting nose. For portraiture, the position of the fill light must always follow the axis of the nose. That means placing the fill to one side or the other of the camera and then placing the main light on that same side, but somewhat further around from the fill. This completely negates secondary shadows and keeps the fill from washing the three dimensional face with illumination that flattens the three dimensional qualities of a human head.</p>

<p>This placement includes working with profiles in which the fill remains in line with the nose (at 90 degrees to the lens) and the main is at about 120 degrees away from the lens.</p>

<p>Again, the bigger the fill, the softer the source and the effect on the subject.</p>

<p> </p>

<p>Another important consideration with the distance of the fill from your subject (and relative to the background) is that the further away it is, the more it will lighten your background. If you want to keep the background dark, get your fill light closer to the subject (if possible) to maximize the fall-off.</p>