In order to understand photography, you need to have a basic understanding of how your camera works. Don’t get scared! Even a six-year-old could understand this. In fact, here’s what your camera might look like if a six-year-old used Paint to draw it:
At the very back of the camera there’s a sensor that records whatever light hits it. We don’t really care much about how this happens right now, since it doesn’t matter. For our purposes, let’s pretend that there are millions of magic camera gnomes that live on the sensor rubbing shoulders with each other and spend all their time waiting for a little bit of light to reach them. When they see light, they get excited and record exactly how much light they see.
If the gnomes always got light they’d get tired and stop working, so right in front of the camera is a shutter. Think of this as a curtain that’s closed almost all of the time, but opens up for a brief moment when you want to take a picture.
Whenever we take a picture there’s a lens attached to the front of the camera, and that’s where the light comes in. The lens has a lot of glass in it arranged in special ways so that everything focuses just so, but we can treat this as magic too. In addition to the glass, there’s a round opening called the aperture or diaphragm. The diaphragm controls how much light gets into the camera– open wide and a lot gets in. If it closes down to a tiny pinhole, only a little bit of light gets through to the gnomes. When you aren’t taking a picture the diaphragm is always open as far as it can be, and when you take a picture it closes down to let the right amount of light in.
When you take a picture, a few things happen really quickly: the diaphragm squeezes down to block out some of the light, the shutter curtain goes up very quickly, the gnomes get all excited and write down what they see, and then the curtain closes and the gnomes go back to waiting.
And that’s it in a nutshell– the magic of photography. In the next few lessons, we’ll learn how to control the aperture, the shutter, and the elves in order to take good pictures.
Next lesson: The three things that go into exposure.