Every camera, from the simplest compact to the most sophisticated single lens reflex, is a light-light box with three basic features: a viewfinder, a lens, and shutter.
The viewfinder is very important. Looking through it you decided whether your picture will be horizontal or vertical, and what and how much to include in the picture. Remember that your camera is a machine-it is you looking through the viewfinder that makes the picture.
The lens is of optical glass and it focuses the light on to the film, forming an image of what is in front of the camera.
It has a hole through which the light passes, and the amount of light is controlled by the size of the aperture. This aperture works like the iris of your eye, it contracts when the light is very bright and opens hen the light is dim. Most lenses have at least 6 apertures. Each aperture opening is referred to as an `f’ number or stop.
Each time you make the `f’ number higher you halve the light entering the camera (8f to 11f). Changing to a lower number doubles the light entering the camera (8f to f.5.6).
The aperture’s other use affects the area of sharpness which is called `depth of field.’ For example, if you focus on a person 3 meters away and set the aperture at f2.8, everything from 2.5 meters to 4 meters will be sharply recorded. Change the aperture to f16 and area of sharpness extends from 2 meters to 5.5 meters.
Also remember; the close the subject is to the camera, the smaller the area of sharpness or `depth of field.
The shutter keeps the light from the film until you press the shutter release. It also controls the length of time the light falls on the film.
There are two types of shutter
a) A leaf shutter made of overlapping, very thin, metal blades incorporated in the lens
b) The focal plane shutter (SLR cameras) which consists of a blind made of cloth.
Shutter speeds are shown on a dial on the top of the camera body. These stops work like the `f’ stops-they double when moved higher, halve when lowered.
The lens aperture and the shutter speed work together to make sure that the right amount of light reaches the film giving a satisfactory print. Most cameras have built-in light meters which measure the light and tell you which aperture and shutter speed to use; others the decisions for you automatically.
It is important to understand the relationship between apertures and shutter speeds. If, for instance, your light meter tells you to use f11 with a shutter speed of 1/125th second, it would also be correct to use:-
• F8 at 1/250th second
• F5.6 at 1/500th second
• F16 at 1/60th second
All allow the same amount of light to reach the film.
Modern compact cameras have either fixed focus lenses set on a distance of about four meters (13 feet), or an autofocus which does the job for you.
Single lens reflex (SLR) cameras have a focusing ring on the lens. Look through the viewfinder and turn the focusing ring until your main subject appears sharp.