Photography Basics: Understanding Aperture
There are three basic elements to capturing good photographs: shutter speed, aperture and ISO (film speed). In this article, we will explore the aperture ring and how it affects your photographs. When you click the button to take a photograph, the shutter opens to expose the film to record the images. The shutter is designed as a series of thin, overlapping petals. They look like petals on a flower, layered in a circular shape. As they are pulled back, a hole appears in the center to allow light in. Aperture is how much the shutter opens; how big that hole gets.
Aperture affects two things. First, like shutter speed, it determines how much light is allowed in the camera. Second, it determines how much of the photograph is in focus. When the light reflected back from the subject enters the shutter it is inverted upside down before it hits the film or digital sensors. The size of the hole determines the size of the light ray that is reflected back on the film. A very small hole, which is represented by a large aperture number like F16 or F22, will allow a lot of the photograph to be in focus. A large aperture, which is represented by a small number such as F5.6, will leave most of the background of the photograph out of focus.
This is important to understand for different types of images. If you look at classic portraits, you will notice that the focus is usually sharpest on the subject’s eyes. The rest of the face falls into a slight, soft focus (which is very flattering for portraits). The background of the image, anything beyond the subject’s face, is very blurred and out of focus. This causes the viewer’s eyes to look directly where the photographer intended them to and not be distracted by a background. To achieve this, set your aperture on 5.6 or lower and carefully focus on the subject’s face. Everything beyond where you focus will be soft and blurred.
On the other hand, you will have situations when you want a lot of information in focus on different levels of the photograph. For example, if you are photographing someone in front of a beautiful landscape. With a large aperture the subject would be in focus, but the beautiful mountains, river, and other elements in the background would be out of focus. Setting a smaller aperture, such as F16, will allow everything from the subject’s face to the farthest mountain peak to appear crisp and alive. But remember, in order to have a small aperture, you have to have enough available light to flood the small hole. Using a small aperture when there is not enough light will result in your photograph being underexposed.
At the same time, using a large aperture in direct sunlight will allow too much light to enter the shutter. That’s when you use what you’ve studied in shutter speed. Using the two elements together, you have complete control over how much light enters the shutter to decide what affects you want. A combination of F5.6 and shutter speed of 1/1000 may be the right ratio to capture a subject in sunlight. The same scene could be captured with a smaller aperture and slower shutter speed. But the photographs will look very different because of the affects of aperture and shutter speed.