The Physics of Photography
The general population has become so accustomed to their simple point and shoot cameras that they do not either notice the poor quality of images that they are producing or do not have the knowledge to produce better images. For those who desire to take better photographs, photography will be an exciting life long adventure. There are many aspects to consider when taking a photograph. A good photograph is well thought out before the photographer snaps the shutter. Whether taking one’s portrait or shooting a landscape in the back yard, things must be lined up just right to get the best possible image. Different techniques are used to produce the exact feeling the photographer wishes to portray in his/her image. Depth of field is one way in which one can manipulate a photograph to produce the exact image desired. Depth of field is how much of the image is in focus from the front of the photograph to the back of the photograph. Emphasis can be placed on a certain subject by obscuring the foreground or background. There are three main features that can affect depth of field. Lens aperture (f-stop), distance from the camera to the subject, and the focal length of the lens (Heart 100).
In order to understand depth of field one must first understand how light works. We can view objects because of light rays reflecting off their surfaces. These light rays are reflected in innumerable directions. In order to capture an image onto film one must be capable of controlling the light rays that enter the camera. This is done through the lens. The lens consists of a mixture of converging and diverging lenses that bend the light so it reaches the film as a real image. The light that passes through the upper portion of the lens is bent downward while the light that passes through the lower portion is bent upward. “This bending process brings much of the light from one point on the subject back together at one point on the film” (Bloomfield 558). The combination of lenses and special lens coatings create the desired index of refraction of the light that
Without the lens, the light from the object would travel in all directions and leave only a diffused image on the film because the light is just as likely to hit the top of the film as the bottom (Bloomfield 558).
Depth of field is a great way to control the mood of an image. The first way to control depth of field is through the camera’s f-stop or aperture setting. The aperture setting controls the diameter of the opening of the lens, determining how much light is let into the camera. A small number such as F-1.4 indicates a large aperture opening and a large amount of light is allowed into the camera. A large number such as F-22 indicates a small opening and a smaller amount of light is let into the camera. The smaller the aperture, the greater the depth of field, creating a photo that is sharp from front to back. Many landscape photographers use this technique to create...