Understanding Light: Beyond the Perfect Modifier
Rather than just searching for the perfect modifier by reading product reviews, a photographer who is learning how to use lighting in photography should learn the overarching principles of light and properties of light to harness them in their photos.
I have lit my photography work with modifiers that cost thousands of dollars each but in a pinch, I have also used bedsheets, a sheet of aluminum foil, and a salad bowl. At the end of the day, the light that hits the subject is still hit by the same LIGHT.
Hard Vs Soft Light
The reason one lighting modifier will never be appropriate for all photography scenarios is that different shoots may call for different types of light. One of the main properties of light is how hard or soft it is.
Hard light creates harder shadows and brighter highlights. Dark shadows and bright highlights create a greater dynamic range. Hard light will create more specular highlights.
A bare bulb strobe with no modifier is a hard light source. It can be more difficult to shoot in hard lighting but this can also create more dramatic effects.
In a scene lit by soft light, the difference between the shadow and highlight is less. Extremely soft light can be shadowless. When a subject’s face is lit by hard light, there will be dark shadows from the chin, nose, and brow.
Very soft portrait lighting may add no shadows at all on the subject’s face. It is up to you to determine what type of light you want.
Relative Size of Light Source
The hardness or softness of light is determined by the relative size of the light source. The smaller the relative size of the light source, the harder the quality of the light. Even though the sun is a huge light source it is millions of miles away. So its relative size is quite small. Therefore the light from the direct sunlight in(with no clouds or haze) is very hard.
Naturally occurring soft light is created by an overcast day with a thick layer of clouds. The exposure is even and there are no highlights because the light source is enormous, the size of the entire sky!
An Elinchrom 69” Rotalux Octabox is a relatively large modifier and is generally used for its soft light. However, the light that comes from it will not always be soft. If the light is placed across a gymnasium from a subject, even though it’s a large object it’s relatively small compared to the subject, so the light will not be particularly soft. If it’s placed 1 or 2 feet from the subject then it’s a very soft light source.
Watch Out for Hot Spots
When evaluating the properties of a lighting modifier the amount of diffusion fabrics between the subject and the light source can also make the light softer. This is because the light from some lighting modifiers creates a hot spot. This means the light they create is much brighter in the center than around the edges.
Light which is not evenly distributed across the edges of the modifier can still have a hot spot. Adding another diffusion panel can get rid of the hot spot, making the light source bigger and softer.
Many famous painters used soft window light when posing their subjects. Shooting with window light is the shooting solution of many photographers. Softboxes and lightbanks were invented to recreate the light from a window which is often an indirect soft source. Master the effects of just one softbox before learning how to light from multiple light sources at once.
Bounced light is a great way to transform hard light into softer light (as any event photographer who has bounced a speedlight off a ceiling knows). This is because you’re replacing a very small light source with a much larger one (the size of the ceiling you are able to illuminate.)
Bounced light can often be very pleasing because it is so evenly distributed. Bounced light is not just for inside- you can often find good bounced light off next to buildings outside.
While many photographers start using reflectors as a supplemental fill light source, I recommend they practice using reflected light only as their key light source as well. A multipurpose reflector like the Savage 40x60” 5-in-1 photo reflector allows for exploring the different types of light that bounces off of white, silver, and gold surfaces.
When light is bounced off white surfaces you will get softer shadows and more accurate colors.
One downside of bounced lighting is that it’s not very efficient.
Silver and Gold Bounce
When light is bounced off silver surfaces, you will get a more efficient bounce than a white bounce, meaning less light output will be lost.
Many other light modifiers such as umbrellas and parabolic umbrellas also come in silver and white options. Gold bounce gives a very warm quality to the light and is usually more efficient than white but less than silver.
Umbrellas are a cheap and quick way to create even light without hot spots. Shooting with this kit of three umbrellas by Westcott allows you to explore the effects of umbrellas for diffusion or bounce.
Inverse Square Law
While you don’t have to be an expert on physics to master photography lighting, there is one physical law that you should understand: the Inverse-square law of light.
Let’s say you have a light source on full power and your subject is 1 meter away from it. If you move your subject double the distance from the light (2 meters) how much of the light’s power will reach it? The natural reaction is to think half power. Unfortunately, that’s not how light works. Instead, it follows an inverse-square law.
According to the law, the power of the light will be inversely proportional to the square of the distance from the source. So if we take a distance of 2 and square it we get 4, the inverse would be ¼. So the answer is ¼ of the original power (not half).
Another example is moving our subject 3 meters from the light. 3 x 3 is 9 so the power of the light source now becomes 1/9th full power.
The inverse square law explains the dramatic drop-off of light over distance.
One-Point Light Sources Only
An important footnote is that the inverse square law applies to one-point light sources. (If you are working with a LED light panel or a led strip or even a very large soft box right next to your subject then the light is not working according to the law.) However, in photography, one point light sources are very common.
Place Your Light Source Carefully
This does not mean you need to have your calculator for photography lighting. What it does mean is that often you can fix your lighting with smarter light placement. Small movements in placement can affect whether the light will fall noticeably on your subject AND background or only on the subject.
Many photographers will put their light on the stand and then only make adjustments by turning the power of their light up or down. They are missing one of the most important adjustments they can make in photography, physically moving the light itself. Light placement also affects the position of shadows which is very important. The shadows created by side lighting are very different than those created by front or uplighting.
Another instance to consider the inverse square law is when shooting more than one person, especially with side lighting. The subject further away from the light is much more underexposed than you would think. Light placement is crucial when lighting multiple subjects with one source.
Color temperature is another important property of light to take into account when using artificial sources in your photography lighting. LED, tungsten, ambient, and strobe lighting can all have different color temperatures. Take a look at my other article where I look into white balance and gels more extensively.
Harness Your Knowledge of Light
Understanding the principles of light can help improve your photography lighting. Observing the properties of light both outside and in your photo studio will help you to master its control. It is up to you to decide the type of light you want to illuminate your scene. Make your creative choice about what to highlight and what to leave in shadow.
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