We don't just see, we perceive. In the first instance our vision is three dimensional
and has a very wide field of view, but that's just the physical difference. What
is more important is that we attach meaning and importance to what we see.
This is why we don't see the "tree growing out of someone's head" when we take the
picture. We do see both the person and the tree, but to us, the person is so much
more important that we ignore the tree and don't really "see" it at the time.
Our vision is also different from the camera's in that we don't take in the whole
scene at once. Although we appear to see a wide field of view, we can only focus
on a very small area at one time. We constantly scan the scene bit by bit and build
up a picture of the view before us. In some ways you could say that our vision is
actually a figment of our imagination.
If you don't believe that, just think of your dreams. When you are dreaming you can
"see" just as well as you can when you are awake, even though your eyes are tight
The other thing our perception does is to compensate. For example, when we see something
in the distance, it will appear slightly larger to us than it is in reality. When
we see only part of a pattern, our perception fills in the missing pieces. This compensation
is the reason why optical illusions work. They supply the visual cues that trigger
our vision to compensate for something thus showing up the difference between perception
All this has caused many philosophers to muse on whether we are actually aware of
"reality" at all, which is heavy stuff. Fortunately we're photographers, not philosophers
and we don't really need to worry about such things. What the photographer needs
to understand is how the camera "sees" and how we can become more aware of how the
photographic process works.
The photographic process
The first thing to realise is that the camera only "sees" light - nothing else. Things
are only seen by a camera if they reflect enough light. This is a combination of
the amount of light they receive and the percentage they reflect. For instance, a
light coloured object in the shade could appear to the camera the same tone as a
dark object in bright sunlight.
Our perception compensates for this. When we know something is dark, we see it as
dark, even if it's brightly lit. We automatically raise the level of dark areas and
lower the level of bright ones so we can see everything in front of us. the camera
cannot do this.
The actual difference in level between the brightest and darkest parts of our scene
is called the contrast ratio. This is a very important concept because we naturally
are hardly aware of it but it means everything to your camera. Another important
fact is that the photographic process has a strict limit on how much contrast ratio
it can cope with.
For example, it is possible for us to read the writing on a light bulb whilst still
seeing the room perfectly well. A camera simply cannot do this. In reality, the light
bulb is so much brighter than the room that the contrast ratio is far too big. The
writing on the bulb is actually hundreds of times brighter than anything else in
the room, except the light itself. In a normal photograph the bulb and its writing
will be completely overexposed. If you reduced the exposure enough to see the writing,
the room would dissapear into the darkness.
A more common but similar situation occurs when you are in a room lit only by windows.
If someone stands in front of a window, you can see them just as well as the scene
outside, even though they are only illuminated by light bouncing off the walls of
the room. Again, this is too much contrast for your camera.
In this situation the photographic process gives you two choices. You can either
expose the view through window properly, in which case the person will be in silhouette
or, you can expose the person properly and let the outside world be very overexposed.
To take a photograph that looks more like what you see you need to light the person
to the same level as the scene outside. This can be done with flash and when it is
it's called fill-in flash. This is a way of reducing the contrast ratio of our scene
so the photographic process produces a result that is closer to our perception.
The above conditions are quite extreme examples but even perfectly normal situations
can have too much contrast. A bright sunny day is a good example, not only is the
light brighter, the shadows are much darker. Anything in the shade will come out
much darker than you would expect. You should also be careful with anything white,
which can very easily be overexposed and have no detail.
This is the main reason why most photographers will tell you that it's better to
shoot on cloudy days. It may not actually be better, but it certainly is easier.
Even here however, there can easily be too much contrast between the sky and the
ground. This will cause the sky to "bleach out" to a white featureless mass. If you
expose for the sky, the ground would look far too dark.
How to see like a camera
Sometimes, if you half close your eyes so you are virtually looking through your
eyelashes, you can get a better idea of the contrast ratio. With digital cameras,
the screen does give you a hint about what the picture will look like. But by far
the best way to understand what is going on is to return to the scene with your photograph
and compare the two directly.
If you do this you will also see the effect that perspective has on your photographs.
Our perception of perspective is based on the fact that we have two eyes and that
makes our vision three dimensional. The camera of course, has only one "eye", so
things are very different. You can get a better idea of how this works simply by
closing one eye.
You won't actually lose your perception of depth or distance by doing this, people
with only one eye can still tell near from far, but you have to use specific visual
clues to do so. For example, if the far distance is very far away, it will often
have a haze covering it, this is one of the visual clues we use.
Another is size. When we see several objects that we know to be the same size, like
fence or lamp posts, we know the smaller ones are further away. If we want our images
to have a feeling of depth or distance, then we have to make sure these visual clues
are present in our photograph. Without them, we may not have any idea of scale in
the photograph. This is often the missing ingredient in landscape photographs that
don't look quite right.
The other big difference between our perception and the camera's view is one of focus.
We can only look at one thing at a time but the camera sees everything at once. We
cannot look at a person and their background at the same time, but the camera does.
How often have you discovered something in the background of one of your shots that
you were just not aware of when you took the picture?
As photographers, we have to force ourselves to deliberately look past our subject
and study their background. If it is in any way interesting, that will probably translate
into something quite distracting in the final photograph. This is why many photographers
use a narrow depth of field when shooting people. This will throw the background
out of focus and make it much less distracting.
The photographic process starts with our perception. That is, whatever it is that
we see in the first place that makes us want to take the picture. A large part of
studying photography is learning how this perception differs from the resulting photograph.
It's partly because the camera can only "see" part of what we do but it's also because
the camera cannot lie. It's obvious really, it doesn't have the mental capacity,
or any for that matter, to lie. Only we do, and we do it all the time. In this regard,
all photographers are really seekers of truth - visual truth.
If you would like to learn more about what is possible with a digital camera and
just how to go about achieving stunning results with your camera, David Peterson
has written a comprehensive guide full of useful practical advice on the whole subject
of digital photography. You can read all about this book on his website.
Read more about “Digital Photography”