Understanding aperture is critical knowledge for new photographers.
Aperture is one of the most important core principles of photography. Camera aperture can be a confusing concept for new photographers. Complicated vocabulary like f-stops, diaphragm, depth of field and exposure can add to the problem of understanding aperture. Automatic exposure settings on modern cameras have allowed virtually anyone to take properly exposed pictures. However, with even a basic understanding of aperture, budding photographers can begin to make educated experiments, creating new and exciting images.
Aperture Basics
Aperture is a term given to the amount of light that is exposed to a camera's film at the time when the camera's shutter is open. Though some lenses and cameras have fixed apertures, most cameras' apertures are adjustable. Larger apertures let in more light while smaller apertures let in less light. Adjusting the aperture to let in the right amount of light given other camera settings like shutter speed and ISO speed will allow an image to properly expose.
Diaphragm
The diaphragm is the moving mechanical system that creates the different aperture settings. Metal or plastic petals are arranged around a ring with a gap in the middle, the aperture. These petals can be adjusted to move out towards the edge of the ring or towards the middle, creating a small hole when moving in and a large hole when moving out. The various hole sizes are the various aperture settings, or f-stops.
F-Stops
F-stops, or f-numbers as they are sometimes called, are the measurement attributed to various aperture settings. F-stops are usually denoted by a lower case f followed by a number. For example: f2.8. This would refer to an aperture of 2.8. Contrary to most intuition, a larger number represents a smaller aperture. Thus, an aperture of 16 (f16) lets in less light than an aperture of 4 (f4). Some cameras may display f-stops digitally, on lcd displays, though some lenses may have the f-stops engraved into the barrel of the lens.
Depth of Field
Depth of field is created as a function of distance of subject from camera and of aperture setting. The smaller the aperture, the smaller the depth of field. For example, a close-up portrait at f8 will create a crisp picture with the entire face in focus, whereas the same picture at f1.8 might only have the nose or the eyes in focus, while the rest of the face is blurred.
Aperture and Shutter Speed: Relationship
The relationship between aperture and shutter speed is very important and fairly simple. In order to maintain the same exposure, shutter speed and aperture need to have the same relationship. Therefore when the shutter speed is increased, or made to go faster, the aperture needs to become larger. If the film is exposed to light for a shorter period of time, then more light needs to be available to the film; therefore the aperture is increased. Similarly, if the aperture is made smaller, a longer shutter speed is required to reach the same exposure.
Tips
When choosing an aperture setting, consider all the consequences of aperture. Exposure and depth of field are two of the most dramatic changes that are achieved with aperture. Do not be overwhelmed by the amount of options that are available on even simple cameras. Try taking pictures of the same subject keeping all variables constant, except for the aperture, and see how the different settings affect the picture.
Tags: shutter speed, aperture settings, depth field, amount light, aperture setting, cameras have