The Power is in Your Hands: Lighting and How it Works Inside Your Camera

If you're going to understand anything about photography, you should first understand how your camera works because a photograph is nothing more than burning light onto something. Inside every camera is a light sensor (obviously, some are bigger and better than others) and that light sensor is exposed to light every time you click the button on your camera. When you click that button, three things happen.

First, a little mirror inside you camera which allows you to see out of the viewfinder flips up and exposes the sensor (that's why you can't see anything while the shutter is opened after you click the button--because the mirror has flipped up).

Second, light enters your camera through the glass at the end of your lens and travels down the tube to the sensor.

Three, the sensor gathers the light and all the information about how the light was received and records it as data on your memory card.

Film cameras were a lot easier to understand because the light literally burned an image onto film based on how much light radiated or reflected off whatever object you focused on. But that's another subject for another time!

So, you're probably wondering why all photos don't come out looking like one big white nothing from all the light. That's because we control the light using three things: aperture (also known as your F-Stop), ISO and shutter speed. I'm not going to go too far into what those things mean because a basic understanding is really all you need.

You aperture determines the size of the hole at the end of your lens when you push the button and let light in. The bigger the whole, the more light. The smaller the whole, less light. Obviously, if you're in a dark restaurant, you would want a bigger hole and if you really were in a snow storm, you would want a smaller whole.

To illustrate the sizes of your lens opening.

The ISO refers to the light sensitivity of your film or in the case of digital photography, your sensor. Higher ISOs equal more sensitivity which will bring out a bit more detail in your photos if shooting in a dark setting, but it will also add a lot of grain or noise (little specks all over your photos when you look at them closely). Lower ISOs equal less sensitivity which means your photo will be darker which is useful if your shutter is open for a long time to create a blur such as in the case of waterfall photos.

ISO 200. Photo by K. W. Sanders

ISO 1000. Photo by jdebner.

The shutter determines how long that hole stays open. (That little button we've been talking about, the one that takes the picture? That's the shutter button.) You can set the shutter for short periods if you want to capture a moving object and make it still such as someone running. You can also adjust the shutter for longer periods if you want to capture the movement of something like the light trail of a car.

4 Second shutter. Taken by me.

1/40 Second shutter. Taken by me.

For most people and for most of the time, the auto focus function will do everything you need. But one day, it won't do enough and you'll want to try something cool that someone else did. I learned by trying to emulate other people and so will you! Don't get overwhelmed by the technical stuff--let it come naturally.

Lighting is such a big topic in photography that I couldn't possible cover it all in one post. So I've only talked about how it works inside your camera and what you can do to control it with your tool, but lighting outside your camera is important too and I'll be writing about that in my next post.