2. Aperture (AV mode)
Aperture is another name for the hole in the lens of a camera
through which light floods into the camera. The diameter of this hole can be
adjusted by using the aperture priority mode, adjusting this controls the depth of
field in an image. The depth of field is a term that refers to the range of distance
that appears sharp in an image.
Lens aperture sizes are measured in f-numbers or “f-stops”, the
lower the f-number the bigger the aperture opening meaning the depth of field is
reduced and light intake is increased. Higher f-numbers mean that the aperture
opening will be much smaller, increasing the depth of field but decreasing the
amount of light able to enter the camera.
The size of the aperture has a direct impact on the depth of field. A
large f-number like f/32 will bring all foreground and background objects in
focus, while a smaller one like f/1.4 will isolate the foreground and blur the
background.
3. In taking this photograph I set the
camera to AV mode and set the
aperture to f/16. This is quite a
high aperture setting and so the
foreground is in focus but the
image goes blurry towards the
background. As less light is let into
the camera the depth f field
decreases.
In this image I set the camera to
quite a medium aperture of f/8.
This makes the depth of field larger
and so more of the image from the
foreground to background is in
focus. This is good for situations
where a larger subject in the
foreground is desired to be in focus
but the background still wants to
remain blurred.
When taking this image I set the
aperture to f/4 meaning the depth
of field was large and so the whole
of the image could be in focus,
from the foreground to the
background. This is good in
situations where you want the
background to be in focus as well
as he foreground, for example if
you were photographing someone
in front of a famous monument.
f/16
f/8
f/4
4. Shutter Speed (Tv mode)
Shutter speed is the length of time the camera’s shutter is open when taking the
photograph. These times are recorded in fractions of a second but are often
simplified so 1/125 sec is shown as 125, 1/15 sec as 15 and so on. Speeds of a
second or longer are shown as 1”, 2”, and so on. The longer the shutter is open
the longer the film or image sensor is exposed to light.
The shutter speed can also change the way movement appears in a
photograph, a short one freezing fast moving objects and long ones blurring
them, often for artistic affect. You must think about your shutter speed in relation
to your aperture as these two settings work together and counter act each other.
Taking an image with a slow shutter speed and narrow aperture and then one
with a fast shutter speed and a wide aperture will get you two photographs of
similar brightness. This means if you want a fast shutter speed to capture a
running athlete, you must compensate by widening your aperture to let more
light in.
When shooting with no tripod you must be sure to use a fast enough shutter
speed in order to avoid camera shake. If the shutter is open too long it will
capture the movement you make while taking the image, even if you thought
you were being completely still.
5. In this photograph I have set the shutter
speed to one one-hundredth of a
second. This is a very quick shutter
speed and means that the motion can be
frozen.
In this photograph I have set the shutter
speed to one-eighth of a second. This is
quite a middle range shutter speed and
as you can see doesn’t freeze the motion
as in the photo above, but shows some of
the motion as blur. This can be done to
create artistic affect but can also just be
camera shake and in this case I think it
was as I was not using a tripod.
This image has been taken with a very
slow shutter speed of one third of a
second. Because of this slow shutter
speed there is a lot of blur and camera
shake. This, if planned can add to the
quality of the photo and give it good
artistic affect, but sometimes it just looks
as though the shutter speed hasn’t been
correctly set. Using a tripod to hold the
camera steady would be a good way to
ensure the only blur I am getting is
motion blur and not from camera shake.
1/100
1/8
0”3
6. ISO settings
ISO is the sensitivity of the image sensor to available light. This sensor is the
most important part of the camera responsible for gathering light and
transforming it into an image.
ISO is measured in numbers, the lower the number, the lower the sensitivity
meaning that if you take a photo in a very bright environment the sensor will not
take too much of it in blowing out the image.
In a dark situation a high ISO is more suitable and will allow the camera to
capture images without the need for a flash. Higher sensitivity does however
come at a price, and the higher the ISO the more grain or noise you can see in
the image. Grain is variation in brightness and colour of an image and
decreases the quality of your photograph.
Each camera will have a base ISO which is the lowest ISO number that the
sensor can produce the highest image quality without adding noise so optimally
you should always try and stick to the base ISO. However in low light situations
you may not be able to do so.
Typically ISO numbers start from around 100-200 and go up by the power of two
so 100, 200, 400, 800, 1600, 3200, 6400 etc. The important thing to take from
that and to ensure you understand I that with each jump up in the ISO numbers
light sensitivity effectively doubles. This also means that when a sensor is for
example four times as sensitive to light it needs four times less time to capture
the image, this is where shutter speed comes into effect.
Example
ISO 100 - 1 second
ISO 400 – ¼ second
This must be considered to ensure that you can freeze motion and get the
quality images you want.
7. In this photograph I used a very low ISO.
In this instance the natural light wasn’t
really good enough to use such a low
ISO setting and so the image is too dark.
In this photograph I used quite a middle
range ISO setting and increased the light
sensitivity slightly, but the image is quite
dim and not very well illuminated.
In this photograph I used a very high ISO
and this illuminated the image very well
where the natural light available couldn’t.
100
400
1600
8. White Balance
White balance is the way you can get the colours in your photographs as
accurate as possible. Sometimes, if the white balance isn't correctly set, images
can come out with an orange, blue or yellow tint to them, and not look like the
real thing. Different types of artificial light can cause these different tints, for
instance fluorescent lights often give an image a blueish look while tungsten
lighting often adds a yellowish tinge to the image. These different tinges are
often called “Temperature”.
Preset white balances often work well and the auto-setting is usually enough to
work out the right white balance for a photograph. Most cameras also have a
manual white balance mode where you tell the camera what white looks like so
it can determine what the other colours in the image should look like. You do this
by taking a photo of a white card specifically made for this purpose, this tells the
camera what the colour looks like in the light conditions of the scene and allows
the other colours to be collaborated accordingly.
9. The white balance settings made a difference to the temperature of the images. The first
two photographs have a warmer tinge to them, as they have been set as the shade and
cloudy settings. These light conditions give a slightly blue look to photographs and so the
camera compensate for this by warming the image, hence the yellow/orange warmth.
The second two photographs have been taken with the tungsten and florescent settings.
These light settings give off a yellow light, especially the tungsten light, so again, the
camera compensates by cooling the image. This is why the photographs have a blue tint.
The idea is to get the white balance right so you cant see a coloured tint over the image
and it just looks accurate, with all the correct colours.
ShadeCloudy
FlorescentTungsten
