Aperture Settings
The aperture setting is a setting, like the shutter speed setting, to control the amount of
light which reaches the film (film cameras) or CCD chip (Digital cameras). The larger the
opening the more light is allowed through. The smaller the setting the less light is
allowed through. Below is a chart which illustrates possible aperture settings of a camera
Okay, now things get a little confusing. Shutter speed settings make sense since we all
know that 2 seconds is longer than 1/500th of a second. However, aperture settings often
confuse beginner photographers because the numbers seem counterintuitive to logical
math thinking. You have to remember with aperture settings the larger the number, the
smaller the hole and the smaller the number the larger the hole. Say this over and over to
yourself as many times as you need in order to remember it. This is a very important
manual photography setting and understanding it will allow for much great control over
the outcome of your final product.
Your aperture setting also controls depth of field, which simply put is the distance that
will be sharp, or in focus, from your foreground to your background. The larger the
opening of your lens the less depth of field you'll have the smaller the opening the more
depth of field you'll have. The diameter of the aperture is measured in f-stops. Depending
on the camera you're using or the resources you're reading f-stops will be displayed a
little different.
F1, f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, f22, f32, f45, f64, f90, f128
Like the shutter speed, changing your aperture settings by one f-stop will effectively
double the amount of light coming through (or cut it in half depending if you’re opening
the hole more or closing it). An aperture of 2.8 will let in twice as much light as an
aperture setting of 4. At the same time an aperture setting of f5.6 will let in half as much
light as an aperture setting of f4.
Let's take a step back now and look at a couple of photographs which will show you how
aperture settings affect the depth of field of a picture. In the following example, the
photographer used a shallow depth of field by using a larger aperture opening (small fstop number). The result is a main subject who's in focus but a blurred background.
Aperture - Size of Aperture
- Depth of Field
F2.8
- Nothing is in focus
- Very Large
F4
- Large
- Some things are in focus, in front and behind the subject.
F5.6
- Medium
- Things are staring to be in focus.
F8
- Small
- More things are beginning to be in focus.
F11
- Smaller
- Even more things are in focus.
F16
- Very Small
- Almost everything is in focus
F22
- Smallest
- Every thing is in Focus
Shutter Speed: Camera Settings
Your cameras shutter speed is a measurement of how long your cameras shutter stays
open when you're taking a picture. The slower the shutter speed the longer the exposure
time. When the exposure is set to 1/125 or simply 125 this means that the shutter will be
open for exactly 1/125th of a second.
Common shutter speed options are
2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000
A shutter speed of 2 would therefore keep the shutter open for 2 seconds, while a shutter
speed of 1/2000 would keep the shutter open for 1/2000th of a second. It is also important
to note that each increase in shutter speed doubles the amount of light coming in. For
example, a 2 second shutter speed will let in twice as much light as a 1 second shutter
speed. Similarly, a 1/15th shutter speed will let in twice as much light as a 1/30th shutter
speed.
Shutter speed will have two major effects on your photographs. First off it, like aperture,
will control the amount of light allowed into hit the film (or CCD chip if you are using a
digital camera). Therefore changing the shutter speed will have an effect on your
photographs exposure level. If you keep the shutter speed open for a long time, for
example 1 or 2 seconds, your picture will be brighter and possibly too bright (overexposed). If you don't keep your shutter open long enough (for example, 1/2000th of a
second) your picture could be too dark (under-exposed).
Secondly, your shutter speed will effect movement within your photograph. A
photograph is simply a recoding of light. If you open and close your shutter speed very
quickly you will freeze a moment in time. Quick shutter speeds are great to freeze fast
moving object while slower shutter speeds can lead to some interesting visual effects
since they will capture movement within a frame.
For example, in the following picture the photographer used a long shutter speed which
kept the shutter speed open for a longer period of time before closing. In this example the
camera must have been on a tripod which ensured everything that was static (maintained
its position) remained in its place. However anything which moved within the photograph
left its trails in the photograph for the duration that the shutter was open for. In the
example below a car s headlights were traced during the films exposure to a car driving
on the following highway.
How to Set Your Camera's Exposure
Now that you understand the settings of both shutter control and aperture settings you
need to know what influence they have on overall exposure. Many of you are probably
familiar with overexposed and underexposed pictures. Overexposed pictures are a result
of too much light coming through, and underexposed pictures are those which are too
dark.
Let's say for example, that we used a fast shutter speed (to limit the amount of light
coming in) and a high aperture number (small home) to limit the amount of lighting
coming in and to capture the greatest detail for a landscape photograph. The following
would be the result.
Notice how in this photograph the subject is underexposed. There is not enough light
shed on the film (or CCD if the camera was digital) to bring out the details of the subject.
In the case above it may have been the intention of the photographer to create a darker
image and often underexposed images are taken intentionally. Your concern is to ensure
you don't take unintentional underexposed images.
Now image you set your aperture setting to a low number (larger opening to let in more
light) and you set your shutter speed to a longer exposure time. The result would be a
photograph which overexposes your photograph. Look at the following example.
Therefore it is important to know how shutter speed and aperture work in conjunction
with each other to determine the overall exposure levels of a photograph. Think of shutter
speed and aperture as a teeter totter. On one side you have aperture and on the other side
you have the shutter speed. As the shutter speed gets set to one increment higher the
aperture setting needs to get set to one increment lower in order to keep the light coming
into the camera the same.
And don't forget that every decrease in shutter speed decreases the amount of light by
half, and every increment the aperture opens doubles the amount of light coming in. You
can therefore use different combinations of aperture settings and shutter speed settings to
achieve the exact same exposure levels. Look at the chart below to learn more about how
to balance aperture settings with shutter speed settings.
Since shutter speed and aperture settings move in equal increments, you can trade shutter
stops for aperture stops and have the same exposure. This gives you a range of aperture
openings and shutter speeds that you can use
ISO Settings in Digital Photography
What is ISO?
In traditional (film) photography ISO (or ASA) was the indication of how sensitive a
film was to light. It was measured in numbers (you’ve probably seen them on films - 100,
200, 400, 800 etc). The lower the number the lower the sensitivity of the film and the
finer the grain in the shots you’re taking.
In Digital Photography ISO measures the sensitivity of the image sensor. The same
principles apply as in film photography - the lower the number the less sensitive your
camera is to light and the finer the grain. Higher ISO settings are generally used in darker
situations to get faster shutter speeds (for example: an indoor sports event when you want
to freeze the action in lower light) - however the cost is noisier shots. I’ll illustrate this
below with two enlargements of shots that I just took - the one on the left is taken at 100
ISO and the one of the right at 3200 ISO (click to enlarge to see the full effect).
100 ISO
3200 ISO
100 ISO is generally accepted as ‘normal’ and will give you lovely crisp shots (little
noise/grain).
Most people tend to keep their digital cameras in ‘Auto Mode’ where the camera selects
the appropriate ISO setting depending upon the conditions you’re shooting in (it will try
to keep it as low as possible) but most cameras also give you the opportunity to select
your own ISO also.
When you do override your camera and choose a specific ISO you’ll notice that it
impacts the aperture and shutter speed needed for a well exposed shot. For example - if
you bumped your ISO up from 100 to 400 you’ll notice that you can shoot at higher
shutter speeds and/or smaller apertures.
When choosing the ISO setting I generally ask myself the following four questions:
1.
2.
3.
4.
Light - Is the subject well lit?
Grain - Do I want a grainy shot or one without noise?
Tripod - Am I use a tripod?
Moving Subject - Is my subject moving or stationary?
If there is plenty of light, I want little grain, I’m using a tripod and my subject is
stationary I will generally use a pretty low ISO rating.
However if it’s dark, I purposely want grain, I don’t have a tripod and/or my subject is
moving I might consider increasing the ISO as it will enable me to shoot with a faster
shutter speed and still expose the shot well.
Of course the trade off of this increase in ISO will be noisier shots.
Situations where you might need to push ISO to higher settings include:




Indoor Sports Events - where your subject is moving fast yet you may have
limited light available.
Concerts - also low in light and often ‘no-flash’ zones
Art Galleries, Churches etc- many galleries have rules against using a flash and,
of course being indoors, are not well lit.
Birthday Parties - blowing out the candles in a dark room can give you a nice
moody shot which would be ruined by a bright flash. Increasing the ISO can help
capture the scene.
ISO is an important aspect of digital photography to have an understanding of if you
want to gain more control of your digital camera. Experiment with different settings and
how they impact your images.