simply the collection of light, to much collected - over
exposed, to little - under exposed. This is how it has
always been in photography. However, there is one
major difference between digital photography and old fashion
In the film days you purchased film with a
certain sensitivity to light. In today’s digital age you can
dial in this sensitivity level, it is called the ISO as
opposed to the film’s ASA or DIN. Now for the similarities,
when you purchased film that was more sensitive you had more
grain in the images and they appeared to be not quite as
sharp. That is true today only it is not called grain but
noise. It is like a stereo when you crank up the volume to
high, you hear noise from the speakers even though no music
may be playing. In a photo this would be an area that does
not have enough information collected about it to make a
changes camera sensors have gotten better and better at
dealing with noise. However, regardless of how good
they are one thing that will always be true is the proper
exposure will always produce the best image.
want to have the proper exposure for the base line of the
camera as this will produce the least amount of noise.
Usually cameras have a base line of around ISO 100 (some
offer a lower ISO but the baseline is still 100 - you have
to research your model). Think of it like this, when you
increase the ISO it is similar to turning up the volume on a
stereo. The more you turn it up the more static/noise you
will hear along with the music. The more your
turn up the ISO the same will happen, the more noise in your
However, if there is not enough light to get
a good shot at the base line it may be necessary to change
the ISO. You should test your camera model to see what you find
acceptable for an ISO. For instance for bug shots you may be
happy with ISO 200 and for snap shots of the family perhaps
ISO 1600 works when you are indoors.
exposure always consists of collecting the proper amount of light
for whatever the ISO is set at. There are only two things
that can be changed to collect this amount, the time
(shutter speed) it is collected and the volume that is being
collected (aperture). So there are three parts to exposure,
ISO, Shutter Speed and Aperture (sometimes called the
The key is in balancing these three items. Many times you
will see it explained as filling a bucket with water.
analogy the bucket size would be the ISO.
You would think a big number would be a large amount of
light but it is not. So a small ISO number needs more
information for the sensor to create the image. The more
information collected the better the photo can be.
To get the
bucket filled there are two values that can be changed, the
time the faucet stays on and how much is going through the
pipe (pipe size). These would relate to the shutter speed and aperture.
To make things
easy one change in any value requires an equal change in
another value. So, if you were at ISO 100, f8 at 125th of a
second and you changed to ISO 200, you would have to change
to f11 and stay at 125th of a second or stay at f8 and go to
1/250th of a second. These would be full stop changes, you
can refine them to 1/3 stop changes with most cameras.
Although they are not exact changes they are close.
An easy way to
remember the f stops is to only remember 2 of them, 1 and
1.4. Then you just keep doubling them and rounding them off.
So you have 1, 2, 4, 8, 16 and f32 along with 1.4,
2.8, 5.6, 11, 22 etc.
do not really understand flash. It can be used two
ways you can use it to supplement your current light or use
it to entirely light your subject.
When you use
it to completely light your subject your flash duration
(time flash is on) will be your new shutter speed.
People see it
as follows, I set my aperture, my shutter speed and my
flash. I looked at the histogram and the image was
dark so I turned up the power of my flash and now I have a
perfect exposure. What most people don't understand is
that the flash intensity did not increase it is not like
turning up a dimmer on a light switch, what increased was
the flash duration (the amount of time it was on). In
order to get good consistent macro images you need a very
short flash duration. To get a short duration you will
need to have the flash head very close to your subject.
Continue to Macro Obstacles