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Exposure Control Modes
Depending on the type of digital camera you bought,
it usually have one or more exposure control modes.
Besides the obligatory Auto mode, many
digital cameras now also provide Scene Modes.
Cameras geared for the serious amateur photographers
also feature Shutter-Priority, Aperture-Priority,
and full Manual modes.
This tutorial explains what they are, and when
and how to use them for best results.
Auto
Auto mode, as its name implies, delegates all
decision making to the camera. Your digital camera
will select the shutter speed, aperture, ISO,
white balance, and other settings it believes
will give the best result in the majority of situations.
Most Point-and-Shoot (P&S) cameras have only
Auto Mode since their intended audience doesn't
-- or necessarily wants to -- know how to select
shutter speed, aperture, and other settings. This
includes most buyers of digital cameras. P&S
digital cameras also typically sharpen the picture
for you in camera and set colours to saturated.
P&S photographers desire pictures that "look
good" right out of the camera -- without
having to do any post-processing in a photo editing
software.
Auto mode works well in most picture-taking situations.
In a few situations -- that may or may not occur
frequently, depending on the kind of pictures
you like to take -- the camera in Auto mode is
unable to reproduce what your eyes see. Some of
these situations include a sunset with deep colours;
fireworks; bright snow or beach scenes; night
scenes; action scenes. The camera is "fooled"
in these situations and capture less than satisfying
results.
Take the example of a sunset. Because we are
looking at the sun, our eyes automatically squint
and our iris closes down. The result is that we
see the sunset colours as rich, saturated and
deep. The camera, on the other hand, has no idea
you are taking a sunset. All it knows is that
when it measures the light level in the frame
bounded by the LCD monitor (or viewfinder), it's
pretty dark. So, it averages it all out and allows
more light in than your eyes do, resulting in
a picture that is too bright with washed out colours.
If your sunsets don't come out with the deep
colours your eyes see, now you know why. The solution:
underexpose the shot by one or more stop. Don't
understand what this means? Despair not, for your
camera probably provides you with a "Sunset"
scene mode that basically does the same thing
automatically for you.
The other scene modes adjust the exposure automatically
(even firing the onboard flash, if necessary),
depending on the mode you select. But do ensure
you use the appropriate scene mode for the situation,
or you will not get the desired results. We will
look at some scene modes below.
By the way, do not take a sunset picture if you
cannot comfortably look at it -- or you will damage
your eyes and may also damage the camera's image
sensor.
Programmed Auto
Program Auto mode is very similar to Auto mode,
but allows you to fix some of the settings so
the camera does not change them on you. For example,
you can fix ISO to 100, and let the camera decide
on the other settings. In Auto mode, the camera
would have changed the ISO if the necessity arose.
This gives you more exposure flexibility if you
understand how exposure works. Typically, the
camera will then also allow you to fix other settings,
such as image sharpness, contrast and saturation;
the type of metering; white balance; exposure
compensation; etc.
If you are learning about photography, you want
a digital camera that has Programmed Auto. If
a picture does not come out as your eyes see it,
you can then adjust one of the settings to compensate
for a picture that comes out too bright or too
dark, for example. In Auto mode, you're basically
stuck. In Program Auto mode, you can make the
camera behave the way you want it to and override
its exposure decisions.
Center Focus
 If
you look in the LCD of your digital camera, there
will be a rectangle at the center of the screen,
commonly called the AF frame. This AF frame
depicts the zone where the camera will focus on.
If your subject is smack in the middle of the
screen, well and good.
But, what if your subject is not in the center
of the screen?
Well, most of the time, we use a handy technique
called Pre-Focus. By pre-focusing, I mean
that we swivel the camera slightly so that the
center rectangle is on the subject, depress the
shutter release half-way to lock focus, then swivel
the camera back for our desired composition, and
depress the shutter release fully to take the
picture.
Pre-focusing is used extensively in action photography
when you know that you want to take the picture
at a certain fixed spot. In this case, you can
pre-focus on that spot by a half-press of the
shutter release, then follow the action and depress
the shutter fully when your subject reaches the
fixed spot. Examples of a fixed spot can be a
basketball hoop, a finish line, a spot right in
front of you, etc.
Area Focus
Area Focus extends Center Focus by allowing the
AF frame to be moved anywhere on the screen. So
now, if your subject is to the left of center,
instead of moving the camera left, pre-focusing
and then moving the camera back, all you do is
move the AF frame left instead while keeping the
camera still!
On some cameras, you can move the AF frame easily
without taking your eye off the LCD or viewfinder.
On others, you need to go into the menu, set Area
Focus mode and position the AF frame where you
want it to be using the four-way controller. And
repeat that procedure for every picture where
you want to move the AF frame. No wonder we don't
use this focus mode as often, preferring instead
to use pre-focusing.
Even then, there is at least one photo situation
where Area Focus is perfect for: macro photography.
When taking a close-up you may want to compose
your picture so that the subject is at one corner
of the frame. Since precise focus is paramount
in close-up shots (depth of field is very shallow),
pre-focusing correctly can be difficult to achieve
since when you recompose you may end up moving
the camera a little closer or further to your
subject. The result is an out-of-focus picture
(your main subject will be out of focus though
other parts of the picture may be in focus).
This is where area focus comes in and saves the
day.
By moving the AF frame on your subject to the
corner of the frame so that it covers your subject,
you can maintain your composition without having
to move your camera, lock your tripod, set your
self-timer, and take the shot -- for a spot on
razor sharp image.
An Example
Here is an example of how Area Focus helped me
achieve sharp focus in a macro shot. The AF frame
in the center of the frame encompasses both the
fir needles and the leaves. Where will the camera
focus on: the fir needles (which is what I want)
or the leaves in the background? In the first
picture, using Center Focus, the fir needles do
not come out as sharp as I want; instead the leaves
get the focus.When I try to pre-focus, moving
the camera back to my composition is enough to
lose precise focus.
Fujifilm FinePix S5000
Programmed Auto, Multi-Pattern metering, Macro
ON
19mm, 1/180 sec., F3.2, ISO 200
I could switch to Manual Focus but I don't trust
my eyes (even with a central enlarged image).
I could switch to Multi Focus and let the camera
decide on the most contrasty area. But why leave
this to chance? I decide to use Area Focus instead.
In the second picture, I move the AF frame to
the bottom left, completely covering the fir needles.
Result: fir needles in focus, leaves in background
nicely blurred.
Fujifilm FinePix S5000
Programmed Auto, Multi-Pattern metering, Macro
ON
19mm, 1/170 sec., F3.2, ISO 200
So, why not try Area Focus, if your camera allows
it? You may find that, besides macro photography,
there are other instances when it is the appropriate
focus mode to use.
We hope you have enjoyed this tutorial. If you
have any questions, spot any errors, or have an
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