Basic Photography

Many of you will already be familiar with the nuts and bolts of photography, aperture, shutter speed, focal length, ISO, and so on. If so, this chapter may not be for you, though you may find some new information. But if you aren't already up to speed on these topics, or need a refresher, please read on. Photography is the process of making images using light, optics, and light-sensitive materials. A camera is essentially a device with a lens at one end, a light-sensitive sensor (or film, if you're old-school) at the other, and various mechanical, optical, and electronic adjuncts to make the whole combination work. Usually there's also a mechanical shutter to block light from the sensor until it's time to actually capture an image. (Some cameras use an electronic shutter.) Lets take each of these components in turn.

The lens is where light enters the camera. It's responsible for bending (refracting) the light coming from your subject so that the light rays coming from one point on the subject come together at a single point on the sensor. At least, that's the ideal. It's never fully achieved, partly because of practical constraints of cost, and partly because even with an infinite budget, fundamental physics prevents reaching complete perfection. There are two main numbers that characterize a lens. These are focal length, typically expressed in millimeters, and aperture, somewhat confusingly written as a sort of fraction such as f/5.6. We'll start with focal length.