I like all different kinds of photography, but my bread and butter is portraiture. And while I’ve been photographing people for more than 20 years I’m still learning and evolving my process on a regular basis. Recently I made a fundamental change that I think almost always benefits the polish and contrast of my portraits, and that is this: to use on-axis fill light.
For years I used a white card or reflector placed on the shadow side of the subject’s face (meaning directly opposite from the key light). This certainly works to fill shadows as it bounces light back into the frame. The closer the reflector, the flatter the light becomes. And too close is often too flat. It’s a fine line, which in practice means I spent a lot of time going from too much fill to not nearly enough.
But when I started adding a frontal fill light—a light placed immediately next to, above, or just behind my camera—I noticed that I gained much more control over the amount of fill, which was more natural looking and gave my images a more polished, professional look. And it eliminates a fundamental problem of using a reflector in any other position.
Some portrait photographers swear by a white card placed below the subject’s chin, just out of frame. But I must confess to not caring for that look. Why is there light coming from below the subject? It’s just so unnatural. But that’s just my opinion. It’s also how I feel about fill light coming from any direction other than the key.
I much prefer the look of one single key light source, with hidden fill only as needed to bring contrast into control. Hidden fill is what on-axis fill provides, because it’s coming from the camera so it’s fundamentally lightening the shadows the camera can see.
In practice I shoot frequently with strobes, which means I’ve got one light for the key, likely a second for the background, and a third one as my on-axis fill. I usually put that fill light strobe in a big shoot-through umbrella positioned immediately behind and above the camera—right over my head. Sometimes I’ll just bounce that light off a ceiling right above or a wall right behind the camera. It’s definitely soft and still pretty non-directional this way, and it still prevents what I most want to avoid with this second light: a second set of shadows conflicting with the key light.
While there are no hard and fast rules, typically a second set of shadows is about the worst thing I can see, lighting-wise, in any photograph and especially in a portrait. It’s why the on-axis frontal fill is usually quite effective: because the shadows it produces are hidden from the camera.
The biggest challenge with on-axis fill is simply avoiding overdoing it. Too much fill and it washes out the key light and becomes a new key—a flat frontal key at that. If you’re the kind of person who meters their lights, the meter reading for the fill should read at least one stop, if not 1.5 to 2 stops, less than the reading for the key. But if you prefer to eyeball it, you can also turn off the key light to see how the fill is doing. It should appear noticeably underexposed but it should also be evident even at this low level. Its job is simply providing detail in the darkest shadows, making for a more polished look and a less dramatic contrast ratio, all the while not conflicting with the light from the key. Without a fill light, a portrait can become very dramatic. If that’s the look you’re going for, great! But when you want pleasing light instead of excess drama, this is where an on-axis fill light excels.