As a video creator, light is one of the most important tools that you have available. At its most basic, you cannot make a film without light, but by manipulating how it falls, its color, intensity and quality, you can change the look and feel of your work in an instant. When you hear people refer to the ‘quality’ of light, they mean whether light is hard or soft. This isn’t how bright or intense your light is, but it means something different. Recognizing and using hard light or soft light has the potential to have a huge impact on your filmmaking.
What is soft light?
Light travels in waves. How these waves disperse across a scene will determine its quality, or whether your light is ‘hard’ or ‘soft.’ To tell if light is hard or soft, you need to look to the shadows.
Soft light, which you might also hear called ‘broad’ light, wraps itself around your subjects and casts gentle shadows over it. The transition between light and shadow will be gradual without any harsh lines. It’s the sort of light that you would expect outside on a day when clouds are diffusing the sun’s rays.
What is hard light?
On the other hand, hard light casts deeper, darker shadows that are distinct from the lit areas of your scene. The transition between light and shadow is far starker and more defined. While soft light envelops itself around your subjects, hard light feels more focused and directed. Hard light is the kind of light you get at midday when there aren’t any clouds in the sky.
It might help to think of soft light as light that comes from floods while hard light is light cast by spots. Of course, there’s no sudden cut-off between hard and soft light - That’s a transition, too. You might want your light to be hard, but not that hard. Light can be soft, but not too soft. It’s for you to manipulate and control to achieve the look you want.
When to use hard or soft light
We might use the term ‘quality’ to refer to soft or hard light, but it doesn’t mean that one is superior to the other. Hard and soft light bring different impacts and effects to your output, and both of them have a place in your filmmaking.
That said, soft light is more forgiving and easier to work with than hard light. The distinct shadows cast by hard light require you to be incredibly precise with your lighting setup and ensure that your actors or subjects are clearly directed. Soft light is much more flattering for your subjects. Where hard light will show every pimple and stray hair, soft light will even things out and feel more gentle.
If you are filming an intense interrogation scene or want to convey menace, suspicion or that a character is dangerous, try making use of hard light. The dark shadows will create unease and claustrophobia and the harsh transitions between light and shadow will put people on edge. Films like The Third Man, The Silence of the Lambs and Zero Dark Thirty have all made excellent use of hard lighting.
The ‘chiaroscuro’ technique, where light and dark are sharply contrasted, is an excellent means of intensifying the drama in a scene.
Soft lighting is much more relaxed and airy. It feels easy and welcoming. You will want to use it for interviews, corporate videos, indoor daylit scenes and anything like a rom-com, soap opera or sitcom. Of course, switching between soft and hard light is a great indicator of a change in tone or mood for your audience. What was light and friendly can suddenly become threatening. When you want to up the drama, move to harder lighting.
Size and distance
Whether you’re looking to create soft or hard light, you need to consider two key factors: the size of your light source and the distance between your subject and your light source.
The larger your light source, the softer your light will be.
The closer your light source is to your subject, the softer your light will be.
It is all relative, though. Your light source’s size and distance will render hard or soft light in relation to the size of your subject. What you might normally think of as small light could produce soft light if your subject is even smaller.
You also need to be aware of how quickly light falls off or loses its intensity, as you move a source away from your subject. This is known as the ‘inverse square law’.
What is the inverse square law?
The inverse square law states that the intensity of a light is inversely proportional to the square of its distance from the subject. More simply, when you move a light source twice the original distance from your subject, it won’t halve its intensity but will decrease 4-fold. Your subject will only receive ¼ of the light it did with the source in its original position.
When you move the light source 4 times the original distance from the subject, the intensity will drop to 1/16 of what it was originally.
By moving your light source farther from your subject, you will be creating harder light, but you might need to adjust its brightness to account for the fall in intensity.
How to create soft light
Big light sources, such as softboxes, create soft light. Big light sources positioned close to your subject create very soft light. Using a diffuser, you can spread out the light created by a smaller light source to soften it. You can also use reflectors to bounce light back into your scene and create smoother shadows. Using multiple light sources, such as a 3-point lighting setup, will create softer lighting.
One basic soft light rule used by some directors of photography is to estimate your subject's size, say a 50×50 cm area for a head-and-shoulders shot, and position a light source of the same dimensions (50×50 cm) in the same distance (50 cm) from it. In this instance, if you want to soften the light even more, it’s probably easier to opt for a larger, rather than closer, light source! If you need to move your light farther from your subject for practical purposes, you can maintain the softness of the light by increasing its size accordingly.
How to create hard light
For hard light, you will want to restrict the spread of your light. Start by using a single light source that is small relative to your subject. To help keep the light direct and focused, you can apply light modifiers such as barn doors, snoots or flags to prevent it from falling where you do not want it. And by moving it farther from your subject, you can make it harder still.
In the hard light vs. soft light debate, you need to consider the mood you want your video to convey. If you're looking to create a positive or light atmosphere, soft lighting is the way to go. If your scene has a menacing or intense feel, hard lighting would do the trick. You can also try alternating between both light qualities to change moods. It will help you add depth to your video and make it more impactful.