Photographing through bars and mesh
One
of the best locations for most of us to photograph animals is the the local zoo.
However, most of the animals are in cages...which, it has to be said, is
probably a good idea, but is bad news for the photographer. You could always
make the enclosure a part of the photo...a picture of a chimpanzee peering out
mournfully through the bars of it's cage can be very effective, but most of the
time you'll be wishing the cages weren't there - although if the tigers are
particularly hungry, you would think you'd be more grateful for the protection
being afforded to you :-)
However, all is not lost. With a little care and thought, it is possible to get
good photographs of zoo animals in cages. The trick is to use two common
photographic techniques; a narrow field of view and a shallow depth of field.
First we'll have a quick look at these two, and then I'll explain how they apply
here. If you are already comfortable with these concepts,
click here to skip past my descriptions of them
to see how they apply here.
Field of View
This is a technical term for how much can be seen in the shot. Basically, the
longer the lens (and, if you like, the more the magnification) the narrower the
field of view. The field of view is usually measured in degrees, and this is the
"angle" that would be created were you to draw a line from the leftmost object
in the picture to the centre of the frame on the camera and a similar line from
the rightmost object, and then measure the angle between them.
OK, let's dump the theory and maths aside. What it boils down to is if you use a
longer lens you not only get a closer view of what you are photographing, but
you also get less of what is around it, as shown here.
Depth of field
This is one of the most misunderstood concepts in photography. The reason it's
so misunderstood ? Biology. Seriously ! The human brain is an amazing thing,
closely matched by the human eye. Try this...look at the computer monitor in
front of you, then quickly look at something further away - a window or some
such. Notice anything ? Well, for a start, when your eye moved from one to the
other, you probably blinked, but, even if you didn't, you immediately saw both
things in perfect focus (glasses allowing, if you wear them). The point is this
- the human eye, coupled to the human brain, provides an autofocus system that
cannot be matched. OK ?
Now then. Experiment 2. Look at this screen, and hold your finger up somewhere
between the screen and your eye (but nearer your face than the screen). Close
one eye, and focus on the screen. While you look at the screen, your finger will
seem blurry. If you "look" at your finger, the screen will become blurry. This
is because, despite the eye's amazing ability to quickly switch focus between
near and far objects, it can only focus accurately on one thing at a time. It's
the eye's ability to refocus so quickly that means we are never really aware of
this limitation.
Camera lenses have a similar limitation, but with a bit of leeway built in.
Basically, when you focus on a point, there is a certain amount in front of and
behind that point that will also appear in focus when the picture is printed.
This is called the "depth of field". There are three things that determine how
"wide" the depth of field is: Focal length, Focus point and aperture. Now I'm
not going to go into the maths of it all here - there are plenty of books
available that can do a far better job of that than I, so I'll just outline what
impact each of these have on depth of field.
Focal length: A long lens has a shallower depth of field than a short one. So,
for example, if you were to focus on something 10 feet away with a 28mm lens,
you would see much more that is sharp than if you did the same with a 200mm
lens.
Focus point: The closer you focus on something, the shallower the depth of
field. In other words, if you focus on something just a couple of feet away, you
will see that far less is sharp behind than if you were to focus on something
further away. This is particularly pertinent to Macro photography, where the
depth of field (i.e. the range of distances from the lens where an object will
appear sharp) is measured in centimetres or even millimetres ! One quirk of this
is that the depth of field usually extends twice as far behind the focal point
as it does in front...i.e. things closer to the lens are less likely to be in
focus than things behind the lens.
Aperture: Because of the way a lens is constructed (and the laws of physics) the
smaller the hole that light goes through, the bigger the depth of field, or, in
other words, the more will be in focus. So a photo taken with a lens set at f5.6
will have far less that is sharp than if the same photo were taken with the lens
set at f22 (modifying the shutter speed to match, of course !)
At the Zoo
OK. Still with me ? Good. Let's now go back to
the zoo and apply all this to our photographs. We want to take a photo through
some bars or mesh of an animal. If the animal is very close to the bars, there's
little we can do about it, and will have to include the bars in the picture
(unless we get close enough for the bars to be out of the picture and just take
a close up of part of the animal). So hopefully we've found somewhere to
photograph from where the animal is quite a long way from the bars. This means
that, providing the bars are between you and the animal (and if not, what kind
of zoo are you in ?!), putting them before the focal point and therefore less
likely to be in focus.
What we want now is to get as close to the bars as possible, with the central
portion of the image being through a gap in them. Now we want to zoom in as much
as we can, not only bringing the subject of our photo closer to us, but also
hopefully moving the bars to the edge of the picture or maybe out of it
completely. Because we are using a longer lens now, our depth of field is
shallower, so, by focussing on the subject, we put the bars a bit more out of
focus too, making them even less obtrusive. If you have a basic compact camera,
that's about as good as we can get, so take your picture. However, with a more
advanced compact or SLR, we can improve things still more.
We can do this by selecting a wide aperture, thus making the bars even blurrier,
to the point where they will be all but invisible. This actually has two added
bonuses: firstly it gives us a faster shutter speed, which is usually useful
when photographing animals (being alive, they do have a tendency to move!).
Secondly, it not only helps put the bars out of focus, it will also reduce the
focus of the background, making it less obvious that our subject is located in a
zoo.
So there you have it. To summarize:
1) Find an angle where the object of your photo is as far as possible from the
bars or mesh, and you are photographing it through a gap.
2) Zoom in as close as you can to the object (or if you have an SLR, use a
longer telephoto lens if possible).
3) Select a wide aperture (or fast shutter speed if your camera is in automatic
exposure mode, the effect is the same).
There will be times where you can't do this, and there will be times when you
don't want to...but for most of the time this will give you the best results in
a zoo. I hope this helps you.
Happy snapping..
The two pictures above both taken through
mesh cages at London zoo.
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