Whether you have an expensive single lens reflex camera or a simple point-and-shoot, the principles of how the camera works are similar. There are four elements that work together to control how a photograph looks: ISO, White Balance, Shutter Speed, and Aperture. This is part one; in the next article, we'll discuss how what you can do with these four elements.
ISO
The term ISO is a holdover from the days of film cameras, when people chose different speed films for different shooting conditions. In those days, you chose a high-speed film for things like shooting sports or shooting in low light. The compromise was that higher speed films were grainy. People would often choose film of 100 speed for daylight shots and landscapes, 200 for general use, and 400 or 800 for low light or indoor use.
In digital photography, it works very much the same. The higher the ISO number, the more sensitive the sensor is to light. The downside is that it also tends to increase the amount of noise (pixilation) in the picture.
White Balance
This refers to how the camera sees the color white under different lighting conditions. When a camera can get a true read on what white is, the resulting picture will have more color accuracy. Most point-and-shoot cameras let you select a white balance based on common shooting conditions, like Cloudy Day, Sunny Day, Inside Florescent Light, Incandescent Light, etc. An SLR camera will let you manually choose the white balance in a Kelvin reading. A Kelvin reading of 5500 is about what standard daylight is. The lower the Kelvin, the more red the image, whereas the higher the Kelvin, the more blue.
Shutter Speed
Shutter speed is used to stop motion. The higher the shutter speed, the more you can stop fast-moving objects without blur in a photo. The slower the speed, the more detail you can get in something like a photo of a stream.
Aperture
Aperture refers to how wide the lens opens to let light in. The lower the aperture, or f-stop, reading, the more light can hit the sensor. An aperture of f2.8 is considered “fast.” Most basic lenses have variable apertures of f3.5-5.6. Higher end lenses often have constant 2.8 apertures over the entire telephoto range.
Aperture is used to create depth-of-field in a picture. Depth-of-field refers to how much of an image is in focus. For instance, a shallow depth-of-field means usually only the subject is in focus; anything behind the subject is blurry. This can create great highlight shots. A low aperture setting will give you a shallow depth-of-field. A large depth-of-field means most of the image is in focus, which is good for landscape shots, and is created with a high aperture setting of f11 to f22.
