Aperture (AV mode)
When you take a picture and you hit the shutter release button on your camera, a hole opens
up that allows the camera’s image sensor to catch the scene you’re capturing. The aperture
that you set impacts the size of that hole. The larger the hole the more light that gets in and
the smaller the hole the less light is taken through. Aperture is basically the size of the
opening in the lens when a picture is taken.
Aperture is measured in f-stops (f/4, f/6, f/16). So moving from one f-stop to the next doubles
or halves the size of the hole in the lens and the changes the amount of light getting through
into the camera. The larger the f-stop the smaller the aperture. And the smaller the f-stop
number the larger the aperture.
The aperture effects the depth of field which is the amount of the photograph which will be in
focus. A large depth of field means that most of your image will be in focus. So a small or
shallow depth of field means less of the photograph will be in focus.
Aperture has a huge effect on the depth of field. It explains that the large aperture (the
smaller f-stop- f/4) will decrease depth of field while smaller apertures (f/16) will give you
larger depth of field.
The lower the number, for example F4.0,
it will produce a larger aperture and the
depth of field smaller which decreases
the focus in the photograph which can be
seen as the foreground and background
around the glue stick is out of focus but
the centre of the stick, where the depth
of field has been focused on the image is
sharper but not all in focus. This is a
good technique if you are wanting to
focus in on one specific part of a image.
This is an example of a mid aperture
which focus’s on part of the image, it
creates more than a small aperture but
less than a larger aperture. It makes the
image look shaper and more objects will
become visible but some bits are still not
in that depth of field creating them to still
be slightly out of focus and blurry.
F16.0 was the highest aperture I could
achieve before the camera shake
distorted the photograph, therefore a flat,
stable surface or a tripod will need to be
used. This is the aperture which creates
the depth of field to show almost all of
the objects in the photograph in focus. It
makes the image look sharp and all
details can be seen. You can see in this
photograph that it is slightly darker than
the above images. This can be changed
with the ISO settings.
Shutter Speed (TV mode)
The shutter speed is the amount of time that the shutter is open. It is measured in fractions of
seconds such as 1/60. But anything slower than 1/60 of a second is difficult to capture without
a solid surface or a tripod because the camera shake will distort the image.
If there is movement in the scene you are wanting to shoot such as a moving train or water or
traffic, you have the choice of either freezing the movement so it looks still or letting the
movement go intentionally blur to give it a sense of movement.
To freeze a movement in an image you will need to choose a faster shutter speed and to let
the movement blur come into your image you will want to choose a slower shutter speed.
Motion and movement is good in a image such as taking a photo of water flowing and you
want to show how fast the water is flowing. But my favourite style of slow shutter speed is
when you are taking a shot of the star scape and want to show how the stars move over a
period of time.
A quick shutter speed is also effective with water. It will freeze the frame and create a lot of
detail and sharpness showing each water droplet. This is popular in water sports such as
surfing and diving.
The use of a slow shutter speed
increases the amount of movement in
the photograph, almost making the
scene a blur. This is because the sensor
picked up a lot of light creating a
movement scene. A slow shutter speed
can be effective but when using a slow
shutter speed the use of a tripod or a
solid surface will decrease the camera
shake. Camera shake has been detected
in this photograph, this can be shown on
the sign above. It should not be blurred
like the moving hands if camera shake
was not there.
A middle setting such as 1/50 creates a
bit of movement but not as much as the
slow shutter speed above. The biggest
difference from the image above and this
image is that the objects that are not
moving are sharpened out more and are
more visible and in focus.
This is a quick shutter speed at 1/800. It
makes the whole picture freeze and
shows a lot of detail. A problem I came
across with this setting was the
darkness. This was possibly because of
the lighting inside, if it was done outside
the outcome would have been different.
Also the ISO setting has also been put to
it’s highest to let as much light in it can
and by doing this it has brought in a lot of
noise making the quality of the image
ISO measures the sensitivity of the image sensor. The lower the number on the setting of
ISO, the less sensitive it is to light. But the higher the ISO level creates noise. Noise distorts
the photograph with particles and light that passes through the camera. But a high ISO is
needed in dark situations.
Image noise is random variation of brightness or colour that pass through the image. It is
usually an aspect of electronic noise and cannot be seen unless on a photograph or film.
For example in my own photography if you zoom in you can see small particles of noise
shown by small different colours in the photograph. It is more visible in photographs taken in
a very dark place.
Example of noise from my photographs
A lower the ISO level such as 100 it
means the the less sensitive the camera
is to light therefore it does not let much
light in, making the photograph much
darker. Although the photograph may be
dark the chance of noise is unlikely.
Setting the ISO at 600, lets in just
enough light but it can sometime still be
a bit dark depending on the situation.
The noise may be visible but only if you
zoom in a lot.
With such a high ISO level the creation
of noise can be visible if it is zoomed in.
Noise is not a good thing in a
photograph. It distorts the image and
shows incorrect colours.
White balance (WB), is the process of removing unrealistic colour, so objects which appear
white in person are white in the photograph. The white balance in a camera has to take into
account the "colour temperature" of a light source, which is the warmth or coolness of white
light. Without taking both features into account you could produce a distorted coloured
photograph. But some photographers purposely change the white balance setting to create a
different feel to their photography. For example shooting a cold, wintery scene a white
balance setting such as Tungsten Light would be used to make the photograph look colder
with the different hints of shades of blue. The other end of the scale will filter the photograph
to look warmer.
Our eyes are very good at judging what is white under different light sources, but digital
cameras do not and need the help of auto white balance (AWB).
White Fluorescent Light
Auto white balance will generally correct the white in a photograph but if for example you
want your photograph to look cold a setting such as Tungsten Light or White Fluorescent
Light would be used. And at the other end of the scale to give the photograph a slightly
warmer feel to it with shades of yellow and orangesettings Shade or cloudy would be
used. Each setting creates a different white balance which creates different shades and
almost a filter look on the image.