by Terry Girard
Introduction
Exposure is the result of aperture and shutter speed. When you change the
combination of these two settings you will change the exposure of the shot. Let
us take a look at these two settings.
The shutter speed is the length of time that light is allowed to reach the
sensor. A faster shutter speed will freeze any action while a slower speed can
be used to blur action. Depending on the subject you are shooting there are many
shutter speeds you can use to attain the effect you want. Keep in mind that when
you change the shutter speed you will need to adjust the aperture in order to
keep the correct exposure.
When you change the aperture you adjust the amount of light that reaches the
sensor. When you open the aperture, by selecting a smaller f-stop number you
allow more light through which in turn decreases the depth of field (DOF).
Conversely when you close the aperture, by selecting a larger f-stop number you
allow less light through which in turn increases the DOF.
When you decrease the DOF the main subject is kept in sharp focus while the
foreground and background are blurred. On the other hand by increasing the DOF
the foreground, subject and background are all in sharp focus.
Settings.
Digital cameras are equipped with a number of exposure modes that come in very
handy. Most good quality DSLR cameras have the following exposure modes
available.
The P (program mode) will automatically select both the shutter speed and
aperture in order to produce the correct exposure.
Tv (time value) or (shutter priority) allows you to set the shutter speed you
want while the camera will automatically select the aperture.
Av (aperture value) or (aperture priority) allows you to select the aperture you
wish to use while the camera selects the proper shutter speed.
M (manual) mode is just as its name implies, you set both the shutter speed and
aperture in order to produce the picture as you want.
B (bulb) mode is used for such things as shooting fireworks and other night
scenes when you need a very slow shutter speed.
Set your camera to bracket the shots. This can be done either by an automatic
setting or you can do it manually. Your owners' manual will be able to instruct
you on how to do this. The easiest way is to set it to bracket your shots
automatically. This way the camera will take care of it and leave you free to
concentrate on the composition.
Try the different white balance settings as well. Again there are automatic
settings or you can set it manually. You can produce different effects by using
different white balance settings. For example if you are shooting on a sunny day
set the white balance to cloudy and see how this can soften the colors.
Check the metering setting on your camera. Spot metering samples the center of
the scene but if there is a bright area that is not in the center it may cause
improper exposure. To fix this set the metering to take an average of the whole
scene. Once again the owners manual can help you with this.
Use a low ISO in order to produce richer colors and prevent grainy (noisy)
exposures. If you are indoors or in a low light situation you may have to set a
higher ISO in order to maintain a faster shutter speed. Remember it is always a
good idea to use a tripod in order to prevent camera shake with slower shutter
speeds.
On some occasions you may have an overexposure problem when shooting landscapes
on a very bright day. You can help resolve this problem by locking the exposure.
Point the camera at a darker area in the distance and hold the shutter halfway
down. You can then point the camera at the subject you wish to shoot and press
the shutter all the way down.
Refer to the histogram after each shot. Keep making adjustments and checking the
histogram until the graph is more even. The more even or balanced this graph is
the closer you are to the correct exposure.
Summary.
You can handle exposure in a number of different ways. There are several
automatic, semi-automatic and manual settings you can choose from. Experiment
with all of them and take a lot of pictures. Keep notes on what you do so that
you have good information on what worked best for you.
Keep shooting and have a great time.
By Terry Girard
For more great articles and photography information, including tips and
techniques see my web site.
http://www.ultimate-photography-tips.com
This is a must visit on your photography adventure.
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