The aperture diaphragm is inside the lens.
Aperture is one of two exposure controls in a film or digital camera. Along with shutter speed, the aperture setting determines how much light enters the camera to create an image. The amount of control you have over aperture depends on your type of camera. Different aperture settings can also greatly affect the visual outcome of your photograph in terms of its focus.
Physical Description
The aperture is a diaphragm inside your camera lens. With an older analog film camera, you can control the size of the diaphragm opening by turning an aperture ring located at the base of the lens. Newer cameras offer a digital display panel from which you choose aperture numbers to set the size of the opening. When you press the shutter release button, the diaphragm opens to the specified size you have chosen.
The Term F-Stop
Aperture numbers are also called "f-stop" numbers. They are written with an "f" followed by a slash, such as "f/4." Standard f-stop numbers for film cameras include f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 and f/32. These numbers may vary with a digital camera depending on the size of its sensor. The higher the f-stop number, the less light enters the camera. For example, an f-stop setting of f/8 lets in half the amount of light as f/5.6 but double the amount of light as f/11.
Image Effects
A higher aperture number brings more of the composition, from foreground to background, into sharp focus. Choosing a lower aperture number narrows the depth of field in your image, creating blur in planes other than the one you have focused on. Some lenses come with a depth-of-field scale that allows you to determine which parts of your image will be sharp or blurry based on your chosen aperture.
Relationship to Shutter Speed
While aperture controls the amount of light you can let into the camera, shutter speed controls the amount of time that light enters the camera. The two controls have a reciprocal relationship. When you choose a very fast shutter speed to freeze motion in your image, you likely will have to choose a very wide aperture to compensate and make a proper exposure. Your light meter serves as a guide to how much exposure you will need for a given lighting situation, including determine your aperture options.
Aperture and Camera Types
Professional cameras, including single-lens reflex cameras (SLRs), twin-lens reflexes, large formats and most rangefinders allow you to choose your aperture setting. Typical point-and-shoot film cameras have a fixed aperture that attempts to bring most of the image into focus. This lack of control creates a simpler camera but can cause blurring due to the resulting slower shutter speed needed in low lighting. Some digital point-and-shoots allow you to choose your aperture.
Tags: shutter speed, amount light, enters camera, light enters, light enters camera, your aperture, your image
