Direct Vision Finder Camera
These cameras are equipped with an optical finder, but the angle
of view is slightly bigger than that of the camera. The view of
the camera is outlined by a white frame. The biggest disadvantage
of these cameras is that the eye does not see what the camera 'sees'.
A dirty lens or an unremoved lens cap is only seen on the final
Most of the modern cameras are equipped with an 'auto exposure'
system and are very popular amongst amateur photographers.
Twin Lens Reflex Camera (TLR)
The twin lens reflex camera is two cameras in one body. One camera
is used for framing the picture and for focusing; the other for the
actual photography. Most twin lens reflex cameras use 120 film and
produce square negatives of 6 x 6 cm. They are not popular any more.
Single Lens Reflex Camera (SLR)
This is the most popular camera design and most single lens reflex
cameras use 35mm film. A single lens is used for viewing the image
and for the actual photography. A hinged mirror behind the
lens reflects the image via a pentaprism to the eye of the photographer.
When the shutter release is pressed, the mirror swings out of the
way so that the film can be exposed.
Technical or Studio Camera
Most of these cameras are large-format cameras for film sizes of 9
x 12 cm and bigger and are used mainly by professional photographers.
It is important for a photographer to be familiar with the position
and function of the controls of the camera. Consult the camera manual
if you use a camera for the first time.
Two vital controls on the camera are the aperture setting, also called
the f-stop and the shutter speed control. These two settings control
the amount of light that reach the film.
The aperture (lens opening), also called the f-stop, works like
the pupil of the eye. It can be opened and closed by turning the
f-stop ring on the lens. Typical values are 1.4, 2, 2.8, 4, 5.6,
8, 11, 16, 22 and 32.
These numbers refer to the relation between the diameter of the
hole and the focal length of the lens and should be read 1:8 or
1:11. This means that an aperture of f8 on a 50mm lens has a diameter
of 50/8 = 6,25 mm. An aperture of f8 on a 200 mm lens has a diameter
of 200/8 = 25 mm. Thus f8 on a 50 mm lens is smaller than f8 on
a 200 mm lens. The apertures are designed so that each subsequent
aperture lets in half as much light as the one before.
The aperture does not only determine the amount of light that falls
on the film, but also influences the depth of field. A small lens
opening, say f16 will cause more fore- and background to be in focus
than a lens opening of f4.
All cameras are equipped with a shutter, either a diaphragm shutter
or a focal plane shutter. Diaphragm shutters are situated between
the elements of the lens and consist of three or more thin metal
blades. Focal plane shutters are situated just in front of the film
and consist of slatted metal or opaque fabric blinds. The blinds
form a slit through which light passes onto the film while the slit
passes across the film.
The amount of light that reaches the film is controlled by the time
the camera shutter stays open - 1 s, 1/2 s, 1/4 s . . . 1/2000 s.
Each time setting is half the time of the setting before. The shutter
speed is also used to indicate or freeze movement. A fast moving
object will produce a blurred image on film if taken with a slow
To prevent camera shake it is best to use a shutter speed faster
than the reciprocal of the focal length of the lens. Example: with
a 50 mm lens use speeds faster than 1/60 s, with a 100 mm lens use
speeds faster than 1/125 s. For slower speeds use a tripod or bean
Most cameras today have a built-in exposure meter. The exposure
meter indicates suitable lens opening and shutter speed settings
for a given film. Set the film speed (ISO, ASA or DIN) on the
camera, otherwise the exposure meter reading will be incorrect.
Exposure meters are calibrated to expose film to yield an average
density of 0,74. This should give a middle grey on a positive
print and match the grey of a 'grey card'.
A 'grey card' is a 20 x 25 cm piece of neutral grey cardboard
that reflects 18% of the light falling on it. It is a handy tool
to determine exposure, lighting ratios and colour balance. In
the 'Zone System' the range of grey tones, from black to white,
is divided into 11 Zones. Black is referred to as Zone 0, white
as Zone X and middle grey as Zone V.
Modern cameras are equipped with sophisticated electronic circuits
and will not function when the battery is flat. It is advisable
to have spare batteries handy.