Evening star. [volume] (Washington, D.C.) 1854-1972, 1956-02-26
CAMERA ANGLES
BY A. ]. WEDDERBURN
Curator Of Photography
The Smithsonian Institution

The Smithsonian Institution
Whether you get what you
want when you press the but
ton" on your camera depends
largely upon the lens stop
shutter speed combination you
select.
While most camera fans
know there are numerous COM
binationS of aperture-shutter
speed that will produce iden-
teal exposures, confusion ex-
lists as to why one combina-
ton, in one situation, is best
for a picture, but, in another
set of circumstances. a differ
ent combination is better.
So let's delve and see where
the difference lies.
On the lens-shutter unit Of
your camera will be found
numbers that indicate how
these components may be set
to give you a multitude of ex-
posture combinations. One ele-
ment fixes the size Of the lens
openings; the other allows you
to determine the speed of the
shutter.
We will assume you will use
an exposure meter, adjust 1t
for film speed and the given
light reading and then refer
to the indicated choice Of COM
binationS on the dial. Upon
reference to the meter you will
see that you have a choice Of
lens aperture-shutter combi-
nations. These will run from
large aperture-fast shutter
speed to small aperture-slow
shutter speed.
The question, then. Is which
to use?
How Controls Function
Now let's understand how
each control works. The lens
aperture or f-stop size deter
mines how much light is al
lowed to pass through the lens
to the Aim during a given pc
riod Of time. On the other
hand the shutter controls the
length Of the period in which
the light passing through the
lens Is allowed to reach the
film.
1t can be seen that either Of
these controls can be used to
regulate the amount Of light
which reaches the sensitive
emulsion of the film. Which to
use for the purpose will de-
pend on what film you are US
ing plus the existing lighting
conditions and the nature Of
the subject to be photo
graphed.
Let's say you want to take q
closeup portrait of q person
and he sits in front of q brick
building. II We are looking ut
the image through q ground
glass finder we will naturally
Ito focus) open the lens aper-
ture to its widest opening for
clarity Of vision.
Chances are. If the subject
is several feet from the wall,
the bricks will not seem in de-
tail with the lens focused on
the subject.
Details Become Sharp
But now close the lens aper-
ture slowly while keeping your
eye on the ground glass image.
As the aperture becomes
smaller the background detail
becomes sharper and the brick
wall intrudes itself in the pic
ture. Open the lens and you
will see the brisk detail fade
until It is q blur once more.
In other words, the smaller
the lens opening the greater Is
the depth Of focus. So 1t Is
obvious that in q situation Of
this kind you would select from
the several lens-shutter COM
binations available, one that
would allow the maximum lens
opening and the fastest shut
ter speed available considering
the film and existing light.
Therefore we can see that
where subject is paramount
and background details unim-
portant or undesirable the
wide aperture fast shutter
combination is the one to use.
This same combination is also
valuable when light is bad,
f1lm speed is slow. and action
is to be stopped.
Now suppose shat we are