Evening star., 1951-03-18
Camera Angles
More Terms in the Photographic Glossary
By Alexander J. Wedderburn
cvrotor Of Photography
The Smlthxonjun institution

~ TiSAOHOGI - VSOOeBUutU
cvrotor Of Photography
| The Smithsonian Institution
We resume our glossary Of pho.
tographic terms which Is intended
to keep you familiar with words
and phrases that are peculiar tc
the field of photography.
Abrasion marks" are sometimes
found on Photographic printing
papers, generally of the bromide
variety. as a series Of fine black
lines. These papers, which are un-
protected by any coating designed
to prevent this condition, will
show the abrasions marks If SUBJ
jected to unusual stress or pres
sure. Scratches on Aim are also
referred to as abrasion marks.
An acetate base" film is one
which Is composed Of some mate
rial Of cellulose content such o.
cotton which has been acted on by
acetic acid to produce a nonflam-
mable film which is safe for gen.
eral use. This is in contrast to the
old nitrate base film which was in
common use some years ago which
was highly inflammable and which
caused many disastrous fires In
motion picture houses.
In motion picture photography
animated titles" are used some
times for novelty effects. An ami
mated title is one where either
the letters Of the title or the back
ground or both are in motion. A
common form Of the animated
title Is seen often on amateur
screens when q number Of scram-
bled letters or blocks suddenly fly
together to form the title Of the
picture. This is accomplished by
single-framing while the blocks or
letters are gradually moved from
the scrambled position into that
of orderly titles.
Adapter Means Double Duty.
The word. "adapter." is used in
several ways, photographically
speaking. In all cases. however,
it is nothing more than an acces-
sorry which will allow you to use
your camera or other photo
graphic apparatus in ways for
which 1t was not originally In
tended. A film pack adapter. for
instance. will permit you to use
film packs with a camera that
was made to take cut film or roll
film. Other adaptors allow you
to use lenses and filters on cam
eras not originally designed to
accept them.
When we suggest that you "agi-
tate your film during develop
ment and fixing we are asking
that you keep 1t in motion. In
tray development you keep the
film in agitation by removing the
bottom sheet from the stack and
placing 1t on the top and repeat
ing this procedure until develop
ment is complete. In tank pro-
cessing, the film hangers are lifted
and then raped briskly against
the tank as they are lowered back
into place. Without this constant
agitation, air bells or bubbles may
form on the film that will result
in spots that will have to be
worked out on the prints.
So-called "bas-relief" photog-
raphy has the effect or illusion of
making Photographic prints stand
out in relief. This is. as we have
said. simply an illusion. as the
image on the paper is actually just
as fiat as that produced in ordi-
nary printing. The effect is OBJ
tanned by making a positive trans
parency from negative, then fas-
tening the two together slightly
out of register and printing as
though using an ordinary mega
tive. Prints may be made either
by contact or by enlarging.
What Diffusion Does.
The outlines of an image may
be softened through the use of a
"diftuser." This is usually q
screen which is held between the
lens Of a camera and the subject
or similarly placed between the
lens Of an enlarger and the print
ing paper. The screen may be
made of fine or coarse netting,
wire mesh. or material of a like
nature. It is used to de-empha-
size detail and Is helpful to the
portrait photographer who wishes
to play down lines. wrinkles or
blemishes.
An etching knife" or etching
blade" is knife or blade with a
fine edge which is used by re-
touchers to remove excess deposits
of silver from the negative. The
etching knife is used with scrap
ing motion rather than to cut.
The retoucher builds up thin
areas of the negative with a re
touching pencil" which leaves
traces Of lead where the silver is
lacking.
You have probably had the ex-
perience of seeing some of your
priced prints fade" Fading is
characterized by a loss of detail
III the print and the image assum-
ing a yelloWish cast or hue. Due
to improper processing during the
fixing and washing phases Of print
making, fading is actually the re-
suit of the silver of the image
converting to silver sulfide. This
can be prevented easily enough if
you are careful to see that the
prints are thoroughly fixed and
then washed to remove all excess
chemicals before drying.
Film "notches" are simply
rotcheS cut in the upper edge of
the film. These are placed there
so that you can tell in the dark
what type of film you are handling
and which is the emulsion side.
Each film manufacturer has his
own notch code to avoid con-
fusion.
The Focal Plane Shutter.