Undestanding Camera Exposure

Like an eye the camera uses a lens to focus on an image recording area. Aperture is adjusted to control the quantity of light coming through. Underexposed or overexposed image will be mostly black or white. Our aim is to capture between these black and white extremes.

A shutter speed is the other way to control how long each exposure takes. Doubling the shutter speed is one unit in the measurement called F-stop.

Aperture and shutter speed must be combined correctly to capture just the right amount of light and record the full range tones. Too much light causes overexposure and too little - underexposure. Even if it happens to a small degree image details are lost and cannot be recovered.

You can also adjust the ISO setting. The slower the ISO the more details and richer tones it produces. Slow ISO speed gives less noise and grain.