Evening star., 1952-04-13
By Alexander J. Wedderburn
NUrofor OF rnofo9T0phy
The Smithsonian institution

We opened a discussion Of ex-I
posure last week with a rundown
on the use of the exposure guide
or computer. We found that this
handy little gadget would give us
fairly accurate indications of how
to expose for general lighting con-
ditionS. For more critical work, wei
must turn to the photo-electric
cell meter. The meter is more
than handy gadget. If used cor
irectly, it will point out the correct
exposure for just about any situa-
ton we may encounter.
AS a starter. let's get a clear
picture of the light meter-what's
inside the case and just what
happens when we point it at al
scene we wish to photograph.
The works" of a light meter con-
Sist of a photo-electric cell. This
cell converts light energy into
electric energy powerful enough
to move the pointer of a micro
ammeter along a scale to show a
reading in hgnt unlLS Or IN the
case of some meters. the correct
combination of shutter speed and
lens aperture for particular films.
Practically speaking you just aim
your meter at the subject, look at
the scale or dial, and you will find
there all you need to know to make
the proper adjustments of your
camera in that particular situa-
ton.
A few years back there were
two types of photo-electric cell
meters. The meter in general use
was the type that measured re-
f1ected light. This measured the
light that was actually reflected
by the subject to be photographed.
Another meter was that which
measured incident light. An Incl
dent light meter makes a reading
of the power of the light that is
actually falling on the subject
not that which is being reflected
by the subject.
Some Meters Handle Both.
Lately meter makers are Offer
ing products that will measure
either incident or reflected light.
Some meters are built that way
and other may be adapted to in
cident light reading by a supple
mentary attachment that is used
as a converter. We feel that it
does not make any difference
which method you use just so you
do use a meter to figure your ex-
poSureS.
The need for a light meter
should be readily apparent. To
the photographers who only uses
his camera occasionally, one light
ing condition is apt to appear the
same as another while actually
quite a difference may exist. This
difference is often that between a
good and a bad negative unless
we use a light meter to tell us ex-
actly how to set the shutter and
aperture. If we have a meter and
use it as it is meant to be used,
and do this consistently day in
and day out, it won't be long be-
fore our negatives all have a uni
formly good quality which should
mean a great deal to you who has
to pay for the film and prints.
There's more to it than just
pointing the meter at the scene.
And there is more than one way
to use the meter and still get good
results. AS a matter of fact there
are three ways of taking meter
reading-assuming that we will
use the more popular method of
measuring reflected light.
The Camera Position Reading.
The camera position method is
the favorite way of meter reading
of most people-and the quickest.
When you want a light reading
from a general scene or landscape
you simply take the reading with
the meter held at about the same
spot where the camera is sta
toned. In a situation like this
point the meter at the scene you
are taking but point it in a down.
ward direction so that the sky
does not influence the reading.
This may be accomplished by
aiming the meter at point about
halfway between your feet and
the horizon. The sky, remember,
is so much brighter than the rest
of the scenery that if it is included
in the reading, the meter will be
thrown off enough so that the
negative will be underaexposed.
When you are taking closeup
picture of a person or object. or
when something in the picture is
more important than the rest of
the scenery, discard the camera
position method and base your
exposure on a reading made close
to the dominant object. In max
ing a closeup reading hold the
meter at a distance from the OBJ
ject equal to it's smallest dimen-
sion. Also be sure that you don't
make the mistake of taking a
reading of the shadow cast by the
meter or by your hand or some
other part of the body. If a
shadow influences the meter read
ing the result will be an overex-
posed negative. When making a
closeup reading to obtain per-