It's Monday! Thought I'd start the week off with a boring physics lesson. Why not? Physics is an integral part of photography's art.
Light is a naturally occurring, transverse, electromagnetic wave that can be seen by humans and other species.
Light is produced two ways: 1) Incandescence, i.e., the emission of light from "hot" matter and 2) Luminescence, that is, the emission of light when excited electrons fall to lower energy levels. (Luminescent light occurs in matter that may or may not be "hot.")
Light is fast. Real fast! Galileo tried to figure out the speed of light but couldn't: "I have tried the experiment only at a short distance, less than a mile, from which I have not been able to ascertain with certainty whether the appearance of the opposite light was instantaneous or not; but if not instantaneous it is extraordinarily rapid."
We now know, of course, that light travels at 299,792,458 meters per second. (In a vacuum.) For all intents and purposes, leastwise for most people's photography, it might as well be instantaneous.
Intensity is the absolute measure of a light wave's power density. Brightness is the relative intensity as perceived by the average human eye.
Most light is polychromatic. There are exceptions. A laser, for example, can effectively produce monochromatic light.
There are many forms of light, e.g., infra-red, ultra-violet, but for our purposes visible light is the most important. It's how we see. It's what we capture and record on film or sensors.
It's fortunate the kind of photography most of us pursue, infra-red shooters aside, utilizes visible light. Yep! That's a good thing. It enables us to see what we're capturing or recording. BTW, we don't actually "capture" the light. We record it as it reflects and then interacts with various mediums like film emulsions or digital sensors.
As photographers, we manipulate light. We exploit it. We reflect it, diffuse it, and block it. We do this whether it's artificial light (technically, a contradiction in terms) or natural light.
When shooting using natural light, we look for places to shoot where the natural light, the light coming from our sun, is reflected, diffused, or blocked by things in our shooting environments and in ways that enhance, or make pretty, the light falling on our subjects and reflecting back on our recording mediums. We sometimes prefer to shoot when the light is angled or modified in aesthetically pleasing ways: Golden Hour and early morning sunlight are two such examples.
Also as photographers, we need to be observant, critical, examiners of light. To borrow from the religious-minded, we need to "see the light." I know that sounds overly simple and a somewhat redundant phrase. After all, if it weren't for light, we would not see anything at all. Still, far too many photographers don't seem to see the light, the good light, the best light, the cool light. I sometimes wonder if some photographers spend much time at all searching for it?
While it may seem that light is light, all light is not created equal. Leastwise, it doesn't appear equal. It certainly doesn't reflect and refract in equal ways. When it comes to photography, there is some light that is better than other light. Often times, far better.
Again, this stuff all sounds so simple.
But maybe it's not?
While this update might include more than you ever wanted to know about light, you are, as photographers, artists who use light instead of paint, pencil, chalk or pen. I think the more you know about light the better you can become as a light-painter, that is, the better you can become as a photographer.
The gratuitous eye candy at the top is Tori. Who knew a simple lesson in physics might also include a picture of a hot, sexy, half-naked babe? Betcha they didn't use visual aids like that one when you were in a high school or college physics class.