Understanding the relation between aperture, shutter speed and ISO is an important thing to control your digital camera. First, to define different terms is necessary.
Aperture is a small set of blades in the lens that control the light enter the camera. The range of Aperture usually is between these numbers(f/stop): 1, 1.4, 2, 2.8, 4, 5.6, 6, 8, 11, 16, 22, 32, 45. The small number means bigger opening, on the opposite, the larger number means smaller opening. Lens Opening will affect how much light get in the camera. In other words, f/1 is the biggest opening in these ranges, and this f-stop captures the most light. On the other hand, f-stop also represents the deep of field. When the lens opening is getting smaller, the more of the thing would capture more details (including the background information). The more details show that the distance between front and back is getting narrow. Most photographers usually set f/8 as the start point.
Shutter Speed or exposure time is the length of time when the camera sensor inside the camera expose the light. In general, digital cameras goes from 1/4000 to 30s, or even longer exposure. 1/4000, 1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1”, 2”, and so on. From 1/4000 to 1/2000, that means one full stop of light. The shorter the time exposure means less light get in the camera. The longer time exposure means more light get in the camera. 1/500 is a standard for shooting the freeze photos. When you use the faster shutter speed, you can capture the action or movement very clear, like shooting sport competitions. When you use slower shutter speeds, then the result is blurry.
It is so funny to hear that ISO stands for International Organization for Standardization. Photographers just call it “I.S.O.” The ISO controls the exposure by using software in the camera to make it extra sensitive to light. Usually, camera have these numbers for ISO, 25, 50, 100, 200, 400, 800, 1600, 3200, 6400, 12800. The professional camera will have 25600. The smaller number of ISO, means less light; the bigger number means more light. In other words, When you shooting in a bright day, you should use the lowest ISO. When you shooting in the dark place, you should use higher ISO. However, the higher ISO will bring in more “noise”. That will also affect the quality of the image.
Play with these three main settings, you would be able to shoot with your camera in different situations.