Photography literally means “light writing” and just like how the pen impacts the shape of stroke, so does quality of light impact an image.
Because light can further or distort your message, ya need to know how to harness it. Before you starting picking between umbrella or softbox, you need to understand the basic qualities of light and then understand how your light modifier will impact each quality. Let's get started at the very beginning.
Light provides dimension; Light wraps around your subject or scene revealing form, size, depth, and even texture.
The inherent qualities of light are:
Light Color Temperature
Each light has a base color, measured in Kelvin (K).
- Daylight, midday is about 5500k
- Lights above that become more blue
- Lights lower become more warm
Not only does each light have a color temperature, light can throw the color of which it’s bounced… meaning if you have a light that’s next to a red wall that red will be thrown on your image.
Additionally if we mix different colors of lights sources in one scene, you can get a muddied mess (unless it's done with intention).
Though there are plenty of ways to fix this is post production, if you want to solve it in camera (which is most favorable, mind you) you can use gels on your light to colorize them as needed.
When I refer to shape, I'm not saying "circle" or "square" but rather I mean "Hard or Soft."
Soft light is diffused omnipresent beam whereas hard light is very directional.
Shadows are a good indicator if something is hard or soft.
- Soft light (diffused, omnipresent) - soft gradations to shadow
- Hard light (directional) - hard line between light/shadow
Light modifiers help shape and mould the light. The bigger the relative size of the light source (compared to the subject being lit), the softer the light, the smaller the light source to the subject - the harder.
For example if you add a large shoot-through umbrella, when the flash is triggered the light fills the entire umbrella making the light bigger. Therefore the shadows will be softer as opposed to the bare bulb.
The flow of your light.
With every light there’s a starting point and a point where the beam fades to nothingness. That direction will directly impact where the highlights and shadows will land.
Another factor that comes with direction of light, is intensity.
The brightness of your light.
The quantity of light is available impacts your ISO, aperture, shutter speed. If you need more light, you can place your subject closer to your light but don't forget that the relative size of subject to light changed and the softness of light will be impacted. This is where it can get tricky.
Modifying one quality of light impacts the other qualities.
If you change the color, you impact intensity. If you change shape that can impact intensity and color, and so on.
Ready to learn about modifiers? Your next step is Shaping Light, an ebook I wrote just for that purpose.