Evening star., 1950-02-19

We frequently use words, terms,
and phrases that are instantly
recognizable to the average pho
tographer, such as speed" pin
hole" Crop" "fashgun." and
dodge" However, we appreciate
the fact that our readers number
among them a good percentage of
beginners to whom these pet words
and terms may seem unintelli-
gible. Today we discuss and ex-
plain some of the more commonly
uscl expressions and similar ar
ticles will appear in the future.
The term, amateur photog-
irapher" causes some confusion
and no little resentment if not
cautiously used. So let's dispose
of this one at the outset. The word
amateur does not refer in any
sense to the amount Of photo
graphic knowledge possessed by
the cameraman. It means only
that the photographer takes his
pictures for pleasure rather than
for profit. Some of the best pho
tographers in the country are
amateurs and are far ahead of
many professionals both in ability
and knowledge. You have no rea-
son, therefore, to get hot under
the collar if someone (this writer
in particularly refers to you as an
amateur.
Anastigmatic is word you will
hear often in discussions of lenses.
If your camera lens is so described
you may attribute this to mean
that the lens is free from astig-
matism.
What Aperture Means.
When we speak of aperture we
refer to the opening of your
camera which admits light to the
film for the purpose of exposure.
Practically speaking the lens is
the aperture of your camera and
the size of the aperture or open
ing is usually controlled by dia-
phragm or stop. This is simply
a device between the lens ele-
.ments or in front or behind the
lens, which is used to control the
amount of light that passes
through the lens. In the less ex-
pensive cameras, the lens stop is
usually rotating disk contain
ing several circular holes of vary
ing sizes, any one of which can be
brought into position before the
lens to control the amount of
light to be admitted.
More expensive cameras utilize
the between the lens diaphragm
which is a series of thin, over
tapping metal leaves attached to
a rotating ring. The ring is ro-
tated manually to control the size
tof the opening at the middle of
the lens. For ease of operation
the sizes of the openings are
calibrated in lens stops. If your
camera lens is of this type you
will notice the markings, f:4.5,
f:5.6. f:8. etc. It is important to
know that. at a given shutter
speed, widening the aperture by
one stop will double the exposure
and closing the aperture one stop
will have the exposure.
A backlighted scene is one
where the main Illumination is
behind the subject. Similarly a
sidelighted scene is one where the
main source of light is to one side
of the object or view You will
| find that sidelighted scene will
call for a moderately greater ex-
posure than normal and shot
with the sun behind the subject
may demand twice or even as
much as four times that for q
picture where the sun is coming
from over your shoulder.
Speed Applied to Things.
Speed is a term that befuddles
many a sincere beginner. This is
understandable because the term
is applied to film, shutter, anc
lens. All three are of equal i'm
portance in determining what ex-
posure will occur when you trip
your shutter. The shutter, in
cidentally, is a mechanical device
| that regulates the length of time
/ that light is allowed to pass
through the lens. But let's get
back to speed.
Some films are considered fast
and others, slow. depending upon
their relative sensitivity to light
> To make things easy for YOU. the