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Photography
- The Basics
Author:
Jennifer Newton
To
help you get the most out of your new hobby, we have put
together the following about the basic principles of photography.
The principles apply to all cameras, though they vary in
the way they deal with them.
The
Film
Film is available in all sorts of sizes and types. The most
popular is color negative film A "chunk of light" is captured
on the film's surface coating - the emulsion - which is
photo-sensitive.
Film
is available in different "speed ratings". This term is
confusing because what it really means is how sensitive
to light they are. A fast film is very sensitive and needs
less light to produce a picture than a slow film.
For
most purposes you will probably choose from the following
speeds of film:
- ISO
100 Medium speed film for use in bright light for general
photography
- ISO
200 Semi-fast film for use in dull conditions
- ISO
400 Fast film for use in dull conditions or for action
photography
When
you load a film into your camera the first thing to check
is that the film speed dial on the camera is set to the
correct position for the film being used.
Exposure
As I mentioned earlier, the film captures a chunk of light
to create a negative which is used to make a print. In order
for this print to look like the original subject you photographed,
the right amount of light has to reach the film. Too much
light will cause the picture to be too light (under-exposed)
and not enough will cause it to be too dark (over-exposed).
There
are two ways to adjust the amount of light reaching the
film when the picture is taken:
- Alter
the time that the shutter is open - shutter speed
- Alter
the size of the hole that the light comes through - aperture
Shutter
Speed
The shutter speed is like of the stopwatch of the camera.
It sets how long the camera stays open. On most cameras,
all the shutter speed numbers indicate fractions of a second;
that is, the setting "500" means the camera will stay open
for 1/500th of a second.
Commonly
available shutter speeds are 1000, 500, 250, 125, 60, 30,
15, 8, 4, 2, 1 and "B". Note that each speed is half or
twice as much as the speed next to it. 1000 lets in the
least amount of light (camera is open for a very short time)
and is called a "fast" speed, while 1 lets in the most amount
of light (camera is open for a relatively long time) and
is called a "slow" speed.
If
you're taking pictures of things that move, you can decide
to "freeze the action" and shoot at 1000. This will stop
all but the very fastest motion. Perhaps you wish to show
movement, like water splashes or flying dirt (If you have
kids, you WILL have these moments to capture) Then these
photos need to be taken at slower speeds to show blurry
motion.
Experience
and practice will help you decide what you're trying to
do, and which shutter speed you should use. Try taking the
same photo a few different ways and take notes to help you
learn.
At
60 or slower, if you don't have a smooth motion on the shutter
release, the motion you're putting on the camera will show
up as blurry photos. At slower speeds, bracing the camera
is a big help. You can use a tripod, or you can rest the
camera on anything stable that's at hand.
The
"B" setting is special. It stands for "Bulb", and the camera
will stay open as long as you hold the shutter button down.
In photos where lightening is streaking through the photo,
they were made with long exposures (say 30 whole seconds
or more) typically done on the "B" setting.
NOTE:
If you are using the flash on an SLR camera, make sure the
shutter speed is at the correct setting, ususlly 1/60 or
1/125. If you use a faster speed part of the picture will
be black. This is because the shutter will not be open long
enough and will be closing before the flash has fired.
Apertures
The aperture is like the pupil in your eye. It's a mechanical
"iris" inside of the lens that opens and closes to varying
degrees to control the amount of light that passes through
the lens. When an aperture is "wide open", it's gathering
all the light the lens is capable of. When the aperture
is "stopped down", or closed down to a pin-hole, it's letting
pass the smallest amount of light possible.
Apertures
are expressed in ratios. The ratio refers to the focal length
of the lens over the effective optical diameter of the lens.
It's this part of the definition where the aperture picks
up its other name "F-Stop"."aperture" and "f-stop" are pretty
much interchangeable terms.
The
available apertures of the lens on a typical camera are:
2.8, 4, 5.6, 8, 11, 16 and 22. You might notice that every
other number is double / half the next. Each aperture or
f-stop lets in half as much or twice as much light as the
adjacent one.
The
maximum aperture on many cameras is 2.8. This setting lets
in the most light, and is sometimes called "wide open" or
the "fastest aperture". The minimum aperture is 22. This
lets in the least light, and is called "stopping down" or
the "slowest aperture".
In
addition to controlling the amount of light that passes
through the lens, the aperture controls the "depth
of field". A wide open aperture like 2.8 has very
narrow depth of field, while a "slow" aperture like 22 has
very broad depth of field.
Depth
of Field
This is the range of distance which is in sharp focus in
front and behind the point you focus on. The smaller the
aperture the greater the depth of field. Therefore if the
lens is set at f4 it will have less depth of field than
if it is set at f16.
The longer the lens, the smaller the depth of field. When
using a 200mm telephoto lens the depth of field will be
very small even with the lens stopped down to the smallest
aperture (f16). At f2.8 it will be just a few inches making
focusing accuracy critical.
The
depth of field limitation can cause difficulties in some
situations and can be useful in others. If you want to focus
quickly to take an action shot with a telephoto lens you
can lose the shot while trying to focus. Also, you are likely
to want to use a fast shutter speed to stop the subject's
movement and to prevent the picture being blurred because
of camera shake. This will force you to have to open the
aperture to f2.8 which will reduce the depth of field. This
is the reason that fast films are used with telephoto lenses
for action shots. An ISO400 film will allow you either to
double your shutter speed or stop down your lens by one
stop (eg f2.8 to f4) to increase the depth of field. Unless
you want to have large prints made from your negatives,
you will not notice much difference between a 400 film and
a 200, except that the colours may not be quite as bright.
If you have large prints made, however, you will notice
that the picture is more grainy with the 400 film.
The
depth of field phenomenon can also be useful as it allows
you to control the way the picture looks. You have the option
of having all the picture in focus or just the subject
If
you're taking a portrait of someone where the person's face
pretty much fills the frame, typically you focus on the
eyes. If you choose a narrow depth of field by using 2.8,
the ears will be out of focus, and if the depth of field
is particularly small, the tip of the nose will be out of
focus. This can be a nice effect, particularly if the background
has distracting stuff in it.
If
you're taking a landscape picture where there's a field
of flowers in the foreground and a mountain scene in the
background, you might want a very broad depth of field such
as 22 so that the foreground flowers and background mountains
are all in focus.
There
are many books and magazines available to help you develop
your skills. We recommend that you invest in at least one
of the photographer's handbooks. But honestly, there is
no substitute for practice, so GO TAKE SOME PICTURES!!!
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