This article is part of a series of articles on the basics of flash photography. To start at the beginning of the tutorial, click here.
There are many characteristics of light that photographers should learn: color temperature, color, intensity, and more. But this is a crash course so we will only cover the softness of light in this series.
The concept of softness in lighting is difficult for most self-taught photographers to grasp because it is entirely counter-intuitive; however, with a little explanation, you will see that an understanding of this principle will dramatically change how you use light.
Simply put, the softness of light is the measure of how abruptly the transition is from highlight to shadow on a subject.
A more gradual gradation from bright to dark is soft light. A more abrupt transition from highlight to shadow is hard light.
Always remember that the power or brightness of the light source has absolutely nothing to do with the softness of the light. Soft lighting can be achieved with a flash on full power or on its lowest power setting. The same is also true of hard light.
In more scientific terms, this principle is described using the words “umbra” and “penumbra.” You may have heard these words used to describe the lighting conditions during an eclipse or to describe a person’s rights metaphorically, but the same terms apply to photography lighting. The “umbra” denotes an area fully eclipsed by an opaque object. It is the deepest part of a shadow. The “penumbra” is the area of semi-shadow that is only partially blocked by an opaque object and is therefore a lighter shade of gray than the deepest part of the shadow.
Now that we better understand the hardness of the light, let's examine how soft lighting is created, as well as, how the softness or hardness of the lighting affects a photo.
First, how is soft light created? The only way to soften light is to create a larger light source. That sentence is so crucial to your success in learning flash photography that it bears repeating: The only way to soften light is to create a larger light source.
You have seen or, perhaps, used yourself lighting modifiers such as umbrellas or softboxes. The purpose of these modifiers is simple–to create a larger light source. This makes the tiny flash head (the light source) and increases the effective size of the light by tenfold or more by using the entire surface area of the lighting modifier to shine the light onto the subject. If a photographer shoots with only the bare flash and does not use a lighting modifier, the resulting lighting will always be hard light because of the small light source (the flash head).
Some readers may accept the fact that larger light is always softer light and smaller light sources always produce harder light. But if you learn at all like I do, you want to know why. The reason is common sense once understood, but it may require an explanation to see.
Picture in your mind again the face illuminated by a single light. If the light source is a small pen light, only some of the areas will have direct line-of-sight to the light source. Areas on the dark side of the nose, under the cheeks, and on the other side of the face will not have line-of-sight to the light. Therefore, a small light source produces hard light because more areas of the subject have no line-of-sight to the light source.
Now imagine the same face illuminated with a bigger light source, like a lamp with a large lampshade on it. Some areas of the face do not have line-of-sight to the light bulb, but nearly all of the face would have line-of-sight to some portion of the lampshade. The areas of the face (like the bright side of the nose or the side of the forehead closest to the light) that have line-of-sight to the entire lampshade are brighter because more light is hitting those areas. Other areas are slightly dimmer, but still have line-of-sight to part of the lampshade. Very little of the face is in complete shadow from having no line-of-sight to the lampshade. In this example, the lighting is softer from a larger light source. The light source produces softer graduations from highlight to shadow because areas that would not have had line-of-sight to a small light are now hit with light from part of the light shade.
You now understand what soft light is and what makes it soft, but how will this improve your photos? First we will discover why soft light is generally preferred in photos but also why hard light is sometimes appropriate. Then, we will apply this knowledge in a practical sense with specific techniques to improve the softness of the light in your photos.
Most photos benefit from soft lighting because the gradual transition from highlight to shadow allows the viewer to focus less on the lighting and more on the subject. Also, softer light draws less attention to blemishes on the skin because a hard shadow is prevented from showing beneath each blemish.
Soft light has many advantages for flash photographers, but it would be a mistake to think that softer light is always superior to hard light. For example, when photographing sports portraits, I always make a concerted effort to use harder light. The harder light shows off the muscles on the athlete by placing deeper shadows under and around rise of the muscle.
Match the softness of the light to the particular situation and your photos will greatly improve, but most portrait photographers find that they spend much more time trying to soften the light than to create harder light.
So how can you soften the lighting in your photos? We know that the only way to achieve this is to use a larger light, but professional photographers use several tricks for achieving a larger light source without buying larger and more expensive lighting modifiers.
One secret of skilled flash photographers is to carefully monitor the placement of the flash. Suppose you are to take a portrait of someone in a park. You choose to use a small flash shooting through an umbrella off slightly to the right of the camera to illuminate the subject. How can the light be softened or hardened without purchasing a larger light source? Simple! Make the light apparently larger.
Earlier in this tutorial we discovered that only the size of the light source affects the softness of the light. What was not covered at that time is that by saying “size” we really mean the “apparent size” of the light source. In the situation of shooting the portrait at the park, you can make the light become softer by scooting it in closer to the subject, or harder by scooting it further away from the subject. That may sound counter-intuitive, but it is true. From the subject’s perspective, the light is apparently larger when close and apparently smaller when further away.
Photographers often struggle to master this technique. Many times while teaching lighting, I have seen photographers scoot the light further away from the subject after taking a picture and seeing the lighting was not what they wanted. These photographers confuse the brightness of the light with the softness of the light. Scooting the flash closer creates softer light because it is apparently larger to the subject. If the light then appears too bright in the photo, the proper fix is to turn down the flash power. Moving the light further away will surely reduce the brightness of the light on the subject, but it will also make the light harder.
When most photographers start out in flash photography, they have a tendency to place the flash too far from the subject, thinking it will create more beautiful light. Professional photographers often place lights as close in as possible–just a smidgen outside the frame of the photo.
Another pro tip for creating softer light is to look for natural ways to spread the light. A few years ago when I lived in Florida, I was often tasked with taking beach portraits. On a cloudless day, the lighting was almost universally hard because the sun is an apparently small light source. One trick that helped me to achieve beautiful lighting on my subjects is to place the lying, kneeling, or sitting on the white sand beach. The sand acted to spread out the sun’s light and would make the lighting look much softer on the person’s face than when they were standing and the reflected light off the sand had less of an effect on the resulting photo.