Aperture, the amount of light fed into the camera, is controlled manually or automatically. The smaller the number, the wider the aperture. Aperture affects the look of the final photograph and depth of field. Cameras have an aperture range, with a wide range being more beneficial. The wider the aperture, the more light enters the camera, reducing the exposure time needed. Width also affects depth of field. Cameras provide f-stops and exposure recommendations, and some have shooting modes. Aperture and exposure time must be adjusted to compensate for light loss or overexposure. Aperture is important for freezing or blurring motion.
An opening is an opening. In the world of photography, people use the term to describe how much light is fed into the camera. The width can be controlled manually by the user or automatically by the camera. The width of the aperture has a profound impact on the look of the final photograph and as a result, the concept is often introduced at a very early stage in the study of photography.
You will usually hear the aperture designated with a number, such as “1.8” or “16”. The smaller the number, the wider the aperture. These numbers follow a set sequence of increments known as stops or f-stops, and in photographic notation, aperture is usually denoted by an “f” followed by a slash and the number, as in “f/8”. A common range is from f/8 to f/1.4, with f/5.6, f/4, f/2.8 and f/2 in between. The stops are divided by a factor of about two, so f/4 lets in twice as much light as f/5.6, and f/2 lets in four times as much light as f/4.
When cameras are sold, the aperture range of the camera is included in the camera’s technical specifications so that photographers get an idea of the camera’s capabilities. A wide range can be very beneficial, as it allows the photographer more flexibility. Some basic point-and-shoot cameras only have one setting, which can be very frustrating.
Now that you have an idea of what openness is, you probably want to know why it matters. Basically, the wider the aperture, the more light enters the camera, reducing the exposure time needed. Width also has an impact on depth of field, which is the area where things are in focus. When a camera is set to a small aperture, it has a greater depth of field, bringing a variety of objects into focus. The wider the aperture, the shallower the depth of field.
To get an idea of how aperture changes the outcome of a photograph, think about shooting a scene during a sporting event. If you shoot with a wide aperture, giving yourself only a short exposure, you’ll be able to freeze a moving athlete. However, the crowd and the rest of the field will be blurred due to the shallow depth of field. On the other hand, if you shoot with a narrow aperture, lengthening the exposure, you can get a shot of the whole field and you will see the athletes as blurry, because they moved while the film was being exposed.
Many cameras provide f-stops and exposure recommendations on their own, but some allow users to force a specific aperture or exposure duration. As a general rule, if you decide you want a narrower aperture, you need a longer exposure, to compensate for the light loss. If you want a wider one, you will have to shorten the exposure, otherwise the image will be overexposed. Some cameras have a variety of shooting modes that choose the best aperture and exposure for the task, allowing users to select things like “sports mode” or “portrait mode”.
Let’s say you want to take a long exposure photo, such as a photograph of stars as they move across the sky. To do this, you’d need a very large f-stop, allowing a small amount of light into the camera so you could leave the shutter open for a period of hours. On the other hand, if you’re photographing a footrace on an overcast day, your camera may recommend a long exposure to ensure the image pops out. If you want a photo of your friend crossing the finish line, you can widen the aperture by choosing a lower f-stop number, thus decreasing the exposure time so you can get a sharp image of your friend.