PROFESSIONAL PHOTOGRAPHY OF ART
© Ross Sawyers
EXPOSURE CONTROLS
Film Speed
Aperture (F stop)
Shutter Speed
FILM SPEED
The higher the number the faster or more light sensitive the film is. Film speeds are in increments of photographic stops which means that any given film is twice as fast as the film speed preceding and half as fast as the speed following it. Example: 400 speed film is twice as fast as 200 speed film and half as fast as 800 speed film.
SHUTTER SPEED
Most cameras have the following shutter speeds: 1000, 500, 250, 125, 60, 30, 15, 8, 4, 2, 1, 2, 4, 8, B. These shutter speeds are and can be referred to as fractions of a second. So they can be written as 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1/1, 2/1, 4/1. Shutter speeds are similar to film speed in that each shutter speed is twice as long as the speed preceding and half as long as the speed following it.
APERTURE (F STOP)
The aperture is the size of the opening in the lens and is controlled by moving the ring on the camera lens. Aperture numbers are also referred to as F stops. Lenses will have the following F stops: 5.6, 8, 11, 16, 22.
Some lenses will have more stops on both sides. When you are setting your aperture it is important to remember that the smaller the number on the lens, the larger the opening in the lens. Example: F5.6 has a much larger opening than F22.
Aperture numbers are similar to film speed and shutter speeds in that each aperture setting is half as big as the number preceding it and twice as big as the number following it. Example: F16 is twice the size of F22 but half the size of F11.
LIGHT METER
The light meter in your camera is the tool that tells you when you are letting too much, not enough or just the right amount of light into the camera to expose the film. Older cameras will have a needle on the side of the view finder. The needle will point up towards a + sign if there is too much light coming into the camera, will point down towards a - sign if there is not enough light coming into the camera and will point straight in the middle if the amount of light is just right.
SETTING THE FILM SPEED
Once you set the film speed on your camera you will not need to adjust it again until you switch to a different film speed. Setting the film speed is important because it tells the light meter how sensitive to light it needs to be.
SETTING THE SHUTTER SPEED AND F STOP
Setting the shutter speed and F stop (aperture) is very similar to filling up a glass of water. The aperture (F stop) would be the faucet. The shutter speed would be the amount of time the faucet is on. The film would be the empty glass.
The size of the opening in the faucet determines the amount of water that comes out which determines how long it will take to fill the glass. The size of the aperture in your camera determines the amount of light that comes into the camera, which determines the amount of time the shutter needs to open (shutter speed) to expose the film correctly. If the opening in the faucet is small, only a little water will come out taking a longer time to fill the glass. If the opening in the faucet is large letting a lot of water come out it will take a shorter amount of time to fill the glass. This is exactly the same way the camera works.
If the aperture opening is small (F16 or F22) the amount of light coming into the camera will be smaller requiring a longer shutter speed to properly expose the film. If the aperture opening is larger (F5.6 or F8) the amount of light coming into the camera will be greater requiring a shorter shutter speed.
USING THESE TOOLS IN CONJUNCTION WITH THE LIGHT METER
If the light meter is showing that there is too much light coming into the camera you can adjust the F stop, shutter speed or both. If there is too much light coming into the camera you would need to make the opening in the aperture smaller ( go from F8 to F11 for example) or make the shutter speed shorter (go from 60 to 125 for example). You will be adjusting the camera in stops. A stop is the difference between the steps on any of the three control devices.
The difference between F5.6 and F8 is one stop.
The difference between shutter speeds 60 and 125 is one stop.
The difference between 200 speed film and 400 speed film is one stop.
If the amount of light that is coming into the camera is just a little over or under the correct amount you will most likely need to adjust by one stop. If the amount of light coming into the camera is a great deal over or under the required amount of light you might need to adjust by two or more stops.
DEPTH OF FIELD
Depth of field refers to the amount of your subject that is in focus from near to far. Depth of field is controlled by the aperture. The smaller the opening in the lens (F16 or F22) the greater the depth of field. The larger the opening in the camera (F5.6 or F8) the more shallow the depth of field will be. If your depth of field is important to your subject you will want to adjust your shutter speed instead of the aperture when adjusting for a correct exposure.