SIZE Matters, in regards to a light source
There is sooo much information available regarding lighting, but I find that most all of it is confusing and often misleading. Let me tackle one rule of lighting that is simple but often misunderstood: The bigger the AREA of the light source, the SOFTER the light. And when I say ‘softer’, I mean less shadows and contrast.
An excellent example of this is a soft box-
Why is it when we use a softbox our light becomes softer? Most think the light emitting from our flash tube or bulb is softened simply because the light travels through the diffusion material of the softbox. This is not exactly true. The real reason the light is soft comes from the fact that the light is now spread across a larger area. The light spreads to whatever the size of the front diffusion panel of the softbox is (at least with a proper softbox it should). The original point of light (the flashtube/bulb) has been diffused over a larger area. The light is now illuminating your subject from a higher, lower, and wider area, all at the same time. And the bigger the softbox, the more this effect is seen.
Let’s look at another example-
When using an umbrella, the light emitting from the bulb/flashtube is being aimed into the umbrella and is then reflecting out from it. When doing this, the light emanating from the umbrella is spread out. You are now illuminating the subject from a larger area. And, all things being equal, the larger the umbrella the softer the final light.
(Note: There are, of course, variables such as white or silver lined softboxes and umbrellas which may, or may not have an effect on the quality of light).
Remember too that everything is relative. Generally, a larger softbox/umbrella will give a softer light, but it’s really the size relative to the subject that is important. For example- rather than using a bigger softbox/umbrella to create a softer light, one could simply move their softbox/umbrella closer, making it bigger relative to subject…. the same effect will be achieved.
Direct sun equals hard/hash light. That is because that point of light we call the sun is so very small in the sky. But, when the sky is overcast, the sunlight becomes diffused by the clouds. It is spread out above us, illuminating us from many more angles than direct sunlight. It’s like a giant softbox. We may not like the direction of the light (coming from above), but it is soft.
Debunking a term-
There’s a term I hear sometimes that drives me crazy: ‘Wrap Around Light’. It’s usually used to describe the light when using an umbrella. That term is misleading. Light doesn’t wrap around. Light from a larger source will illuminate more areas around a subject, but it is not really wrapping, or bending as some people would lead you to believe.
Debunking another term-
I hear photographers talk about ‘feathering the light’. There is no feathering of light. I mean, no feathering in regards to the light being softer. When you use the edge of the light source the light actually becomes harder. There will be less intensity of light (less amount), but that does NOT make your light softer. The light may appear softer, but that’s probably only because another light source becomes more predominant in the image and is illuminating the shadows (this is what a ‘Fill’ light does). When you turn your light source away from your subject and try and use the ‘edge’ of it you are making the light source smaller relative to your subject, which will make the light harder. A lot of people, including photographers, don’t seem to understand this.
So, speaking of Fill Light-
There’s something to be considered in all of this, and that is Fill Light. The amount of Fill Light will determine how contrasty, or hard, your overall lighting will be. Fill Light can come from many different sources- another artificial light source (flash unit, etc.), light reflected from the main light source via reflector, etc (intentionally or not), or simply from the existing light present (ambient), such as daylight. There is almost ALWAYS secondary light that is playing a part in an image, even if it’s not intentional. As an example- when I fire my flash in a room, the light from that flash is bouncing all around the room. My subject will, of course, be illuminated directly by the flash (whether using a softbox, umbrella, etc.), but also by that same light reflecting off the ceiling, the wall, or whatever else…could even be their clothes. This secondary light is commonly referred to as Fill. The amount of fill has a huge effect on the look of your lighting.
Check this out:
In the image on the left my main flash didn’t go off. The light we see in that image is only from the flash units I had placed behind her to illuminate my background. In the image on the right, the same background light is present, but this time my main light fired, which was a single flash unit with a small umbrella and was the ONLY additional flash unit used. No reflectors were set up. As you can see by the first image, those background lights are providing a lot of secondary light, or Fill.
Note regarding above- Typically, I try and avoid light from the background spilling onto my subject. Putting as much space as possible between the background and my subject helps achieve that. But this shoot was done in a hotel suite, and so I had space constraints. However, I believe I really lucked out because that fill light is doing a magnificent job of adding some highlights and outlining her jaw, which is giving dimension. I believe the term ‘Happy Accident’ applies here.