Controlling the Light
With choices on film speed, shutter speed and f-stop settings (aperture size), the problem can be trying to figure out what the proper light settings are for a given photographic setting. Luckily, the single lens reflex camera helps out with this problem.
SLR (Single Lens Reflex) cameras have light meters inside that help determine the proper aperture ring and shutter speed. The shutter speed settings for many cameras are 15, 30, 60, 125, 250, and 500. These numbers actually represent the portion of a second that the shutter will be open. The setting of 15 means, for example, the shutter will be open 1/15th of a second. The setting 500 means the shutter will be open 1/500th of a second. Thus, the larger the number, i.e. 500, the shorter the time the shutter will be open.
F-stop settings have to do with how much light will be allowed in. The f-stop settings on most 35 mm cameras are 1.9, 2.2, 4, 5.6, 8, 11, 16, and 22, with 1.9 letting in the most light and 22 letting in the least. If you want to see a marvelously detailed discussion of f-stops, check out Advanced Photographic Education and click on "the BIG Question," which, of course, is "What is an F-Stop?"
The lower the f-stop number, the larger the opening, resulting in more light.
The slower the shutter speed, the slower the opening, resulting in more light.
The higher the f-stop number, the smaller the opening, resulting in less light.
The faster the shutter speed, the faster the opening, resulting in less light.