Basic Camera Controls:
Aperture:
The opening in the lens which allow light to enter the camera is called the aperture. Aperture increments are expressed as f-stops.
The basic f/stop increments are:
f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32 (there are additional f/stops in between these basic f/stops in modern digital capture cameras)
Moving from left to right from one f-stop to the next in line reduces the amount of light entering the camera by 1/2 each step of the way. For example; changing the aperture from f/2 to f/2.8 cuts the amount of light entering the camera in half. Likewise, moving from f/2 to f/4 cuts the amount of light to one-fourth of the amount of light entering the camera.
Moving in the opposite direction produces the opposite effect. For example; changing the aperture from f/22 to f/16 allows twice the amount of light into the camera. Moving from f/22 to f/11 allows four times the amount of light into the camera.
It would seem that the larger the f/stop, the larger the aperture, or lens opening. However, we must consider f-stops as fractions. Thus, if we put the number 1 atop each f/stop and create a fraction, 1/22 ( f/22 ) is seen as considerably smaller than 1/2 ( f/2 )as an aperture.
Besides controlling the amount of light entering the camera, the aperture also controls the amount of apparent focus in a photograph. A photograph created at f/2 will have considerably less apparent focus than the same view created at f/22.
Shutter Speed:
Shutter speeds also control the amount of light entering the camera.
The basic shutter speeds are:
B, 1, 2, 4, 8, 15, 30, 60, 125, 250, 500, 1000 (there are other shutter speeds in between on modern digital capture cameras)
These are also considered to be fractions; fractions of a second. So, a shutter speed of 2 is actually 1/2 (one-half) of a second, while a shutter speed of 125 is actually 1/125th of a second. The smaller the number, the longer the shutter is opened. Conversely, the larger the number, the faster the shutter is opened.
Generally speaking, apertures and shutter work in conjunction with each other in that larger apertures are generally used with shorter shutter speeds, while smaller apertures are generally used with longer shutter speeds, under the amount or intensity of lighting.
Shutter speeds can get so slow that we need to steady the camera, either by placing it on a table or similar solid object or a tripod while we create the image. The shutter speeds at which most people can handhold a camera without getting camera shake is usually 125 (1/125th of a second). Usually, most people need a tripod or stable solid object under the camera if the shutter speed is slower than 125 in order to not have a blurry picture from camera shake.
ISO:
The ISO rating denotes the amount of sensitivity of the film or the digital sensor to the light source. The lower the ISO number on the film or setting on the digital camera, the less sensitive to light. Conversely, the higher the ISO number, the more sensitive the film or digital sensor is to light.
Generally speaking, the lower the ISO rating or setting, the 'clearer' the photograph, as the higher the ISO of the film, the more the grain of the film is apparent. On digital capture cameras, the higher the ISO setting, the more digital artifacts are apparent in the photograph.
All three of these, the aperture, the shutter speed, and the ISO, are selected in conjunction with each other to give us the best possible photograph we can create.
