What is the biggest misconception about a camera's aperture? Most beginner photographers believe that the aperture controls the shutter speed or vice versa. Actually, shutter speed and aperture work together to get the best exposure for the image. As a photographer, your primary goal should be perfect exposure. There many ways you can use to further emphasize your subject but we will discuss those in other articles.
A properly exposed image uses a ratio of how much light is entering the lens and how long the shutter is open for. The larger the aperture, small f-stop number, means more light is allowed in. Because there is more light than may be needed, you can use a higher shutter speed to capture motion. Just remember that a large aperture means that the depth of field will be shallower. Be sure that your focus is set correctly on your subject or it may be blurry. Here are a couple good rules of thumb to keep in mind when setting your aperture and shutter speeds.
When shooting architectural and landscape photos, you should start with your aperture shut down to it's maximum. With a small aperture, the depth of field will be at it's greatest and allow for much more detail in focus. The relative size of the subject and location of the camera are what necessitates these settings. Due to the aperture size, you will be using a longer shutter time so plan on using a tripod and cable release for the best shots.
On the other hand, for portrait or other still lifeworks, start with the aperture wide open. The shallow depth of field will help eliminate distractions from the background. Now you can use a higher shutter speed as needed.