Evening star., 1949-02-06
- Camera Angles ~
Proper Use of Exposure Meters
By Alexander J. Wedderburn
Curator Of Photography
The Smithsonian institution


Accurate light measurement is one
Of the prime factors involved in the
problem of correct Photographic ex-
posure. There are very few pho
tographers who can Judge light
accurately enough to compute ex-
posure with the expectancy Of hit
ting 1t right on the button each time.
The majority Of us must rely on the
light meter as q mechanical means
for computing exposure. Lighting
conditions are tricky at best, chang
ing with the seasons-often from
exposure to exposure. Snap judg-
ment of light at the time a picture
is taken usually result in under
exposed or overexposed negatives.
To get the best from each film we
should, whenever possible, use a
light meter for the best results. A
meter will soon pay for itself in
saved Aim.
There are several types Of light
meters but the most practical are
those that operate by means OF q
photoelectric cell. These fall into
three general categories: Those that
measure reflected light, those that
measure incident light and those
that are a combination and can be
used either way. The meter that
measures reflected light is the most
popular at the present time so we
shall devote the greater part Of this
article to a commentary on its use
and care.
Basically the instrument consists
of a photoelectric cell which con-
verts light energy into electric energy
which actuates pointer or arrow
of ia micro-ammeter that indicates
olf| d scale a reading in light units
or, in some cases, the exposure re-
quired for each combination of shut
ter speed, +. stop, and f1lm speed.
This may sound bit complicated
but, really, it works like charm.
About the only thing that you will
have to know is the speed of your
film-the meter will do the rest for
you.
Camera Position Method.
The meter may be used by any
one of three methods. In most COM
mon use is the camera position
method. 1t works best when you
must take a hurried reading or
when you are shooting a landscape
or other pictures involving large
areas. AS you might infer from the
name of the method, the light read
ing is made from the position Of the
camera. The meter Is aimed at the
scene in a downward manner SO that
the sky is not included in the read
ing. To accomplish this the meter
should be aimed at a point about
halfway from your feet to the hori-
zon. If the sky is included 1t is
relatively much brighter than the
rest of the scene and a reading in
fuenced thusly will cause your pic
ture to be underexposed. For similar
reasons, the camera position method
should not be used for scenes where
backlighted water, snow, or ice
would have an undue influence on
the reading.
All light meters are not oper-
ated in exactly the same manner
so we recommend Q close study
OF instructions for detailed oper-
alton OF your meter. But in gen.
eral, after you have ascertained
the reading, the pointer will either
indicate the various Shutter-stop
combinations or VIII furnish you
with the information necessary to
make further adjustments for the
final reading.
For portraits or other pictures
where there is one dominant object
that you wish to render most &C
curately, 1t will be advisable to use
the closeup method. In this in
stance the light meter Is held at q
distance from the object equal to
its smallest dimension. Care must
be exercised to prevent the hand
or meter from casting shadow
on the subject. This mistake would
cause a false reading resulting in
overexposure. It should be pointed
out that If the closeup method is
used to obtain an exact exposure
of the principal subject, other OBJ
iects in the picture may be slightly