Understanding the Science of Harsh vs. Soft Light
“What makes photography a strange invention is that its primary raw materials are light and time.” - John Berger
Size Matters
It’s all about size and placement when it comes to light, and bigger is better. This is a concept many photographers often misunderstand, and it would seem logical that when a light source moves closer to a subject, or becomes larger, the light striking that subject becomes brighter and harsher.
You will often hear descriptors of light in terms of it being harsh or soft. Harsh light is often equated with bright light sources, whereas soft light is often associated with dimmer sources. However, the brightness of the light is not what makes this distinction.
A physical property of light directly related to its harshness or lack thereof is proportional to its distance and size from a subject. As a light source is moved closer to the subject, it softens and, conversely, becomes harsher as it moves away. In terms of size, a larger light source will produce softer light than a smaller source. This is due to a principle known as light falloff and the Inverse Square Law.
Soft vs. Hard
So, what’s the difference? Both types of light have pros and cons suited for a given situation or look. Harsh light yields harder shadow lines or transitions across the subject, and the subject can also cast hard and well-defined shadows. Harsh light can wash out colors, add definition, give an edginess to your subject, and produce bright and focused highlights. Harsh light can also make a subject appear flat and less interesting. Think of the midday sun when thinking of harsh light.
The Role of Distance
Soft light, on the other hand, yields deeper shadows with smoother transitions. It can also add depth. Tonality is often maintained, and colors are more vibrant. Soft light can hide blemishes such as wrinkles and add pop to a subject’s eyes. Soft light is also more flattering, yields fewer highlights, and is preferable to most people. In this instance, think a subject being lit in the early morning hours and at sunset.
In this example, a bare strobe light is simulated three feet away from the subject and then moved to twelve feet away. In order to maintain exposure, the light’s power output has to be increased as it is moved. However, there is a noticeable difference between both images. The transitions in the shadows are more gradual and dramatic when the light is closer, while the shadows are more defined and harsher as the light moves away from the subject. The light is also more uniform, and the subject is more evenly illuminated when the source is further.
Adding A modifier
The light source can also be softened when its size is increased. In this example, a 24” beauty dish is added, which increases the size output of the light in comparison. Notice that both images are relatively close to one another. However, the small light source produces more noticeable highlights on the hair and subject’s face with harsher shadow transitions under the neck. The larger source, however, yields fewer highlights and smoother transitions across the face and neck. Adding a modifier also reduces light output, and in this example, power was not adjusted to compensate for any loss.
There is only one Way to Become Proficient
Find a subject to experiment with. Take a few images and try moving the light closer and further away. You will find that power must be adjusted accordingly to compensate for distance. However, don’t be afraid to experiment and confuse an increase in power with an increase in the harshness of light output. As you get more comfortable experimenting, you will become more confident in trying new techniques on your subjects and find yourself stepping outside your creative box.
Understanding lighting basics such as settings, reflectors, light setups, and modifiers is essential. Still, it is easy to find so much information on the subject that it can be confusing. Using light is an experiment, and there are no rights or wrongs regarding creativity. It is time to consider this often-overlooked addition to your skill set.
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