Night and Low-light Photography Photo Workshop

camera will change the shutter speed. So if

you change the aperture to f/8.0, then half

as much light is being allowed through the

lens, so the shutter speed will double to 1/30

second.

    ■   Manual mode takes some getting used to, and

it is easy to make mistakes because you have

complete control, which may result in either

over- or underexposed images. The camera

shows you how much it believes your settings

will either over- or underexpose the scene,

but it will not adjust anything.

Equivalent Exposures

One of the coolest things about photography is

that different settings can result in the same

exposure. This means that if you need the same

exposure, but want or need a different f-stop or

shutter speed, then you can still get the desired

result. For example, if you want to use a higher

shutter speed to freeze the action, then a wider

aperture allows you to do this. Or, if you want to

use a very long shutter speed to capture fireworks

and the rockets’ trails, then using a very small

aperture allows you to do this. By being able to

use different settings to get the same exposure,

you have creative control over your images.

Because an exposure is created when a specific

amount of light reaches the sensor, you can

change the way that happens. For example, if you

increase the amount of time the shutter is open,

allowing light to reach the sensor, then you can

decrease the size of the aperture so that the

amount of light travelling through the lens is

reduced. This results in the same amount of over-

all light, and thus it is an equivalent exposure.

What makes this all work easily is that the

amount of light is measured using stops, as dis-

cussed earlier. Because a stop of light is the same

if you adjust the shutter speed, the aperture, or

The four modes discussed here are all you need to
get the best results in any lighting situation. The
trick is to know when to use each one and why.

■   Program auto mode is best used in an emer-

gency when you don’t really have the time to
set the camera exactly the way you like it. I
use this as a snapshot mode, and while it is
useful, I don’t use it very often.

■   Shutter priority mode is used when you need

to make sure you are using a shutter speed
that shows the movement in your images as
you want it to be seen. This means that you
have set a fast shutter speed to freeze the
action or have set a longer shutter speed to
show the movement. You can also use the
shutter speed to control the aperture because
you know the way a camera adjusts the scene.
So, if you are shooting in shutter speed mode
and want the camera to use a wider aperture,
just increase the shutter speed by a stop and
the aperture will get bigger by a stop. For
example, if you are photographing at 1/250
second and the camera has picked f/4.0, but
you want a shallower depth of field, then just
change the shutter speed to 1/500 second,
which is 1 stop faster, and the camera will
change the aperture to f/2.8 (as long as your
lens has f/2.8).

■   Aperture priority mode can be used when you

want to make sure that you are getting the
right depth of field, but it can also be used to
control the shutter speed. If you are using
f/5.6 and the camera has picked 1/60 second
as the shutter speed, then if the light stays the
same, you can change the aperture and the

Your camera might have a set of

other exposure modes that are spe-

cific to certain situations, but as these differ from cam-

era to camera and manufacturer to manufacturer, they

are not covered in this book.

note