Agfacolor CT18
Daylight
50
M
Agfacolor CK20
Artificial light
80
M
Anscochrome 50
Daylight
50
M
Anscochrome T100
Artificial light
100
M
Anscochrome 100
Daylight
100
M
Anscochrome 200
Artificial light
200
M
Ektachrome E2
Daylight
32
U
Ektachrome X
Daylight
64
U
H.S. Ektachrome
Daylight
160
U
H.S Ektachrome B
Artificial light
125
U
Ferraniacolor
Daylight
25
U
Ferraniacolor
Artificial light
20
U
Ferraniacolor Dia 28
Daylight
50
M
Fujicolor
Daylight
10
M
Gevacolor R5
Daylight
40
M
Ilford Colorslide
Daylight
32
M
Ilford Super Colorslide
Daylight
64
M
Kodachrome II
Daylight
25
M
Kodachrome IIA
Artificial light
40
M
Kodachrome X
Daylight
64
M
Konicolor
Daylight
16
M
Perutz Color C18
Daylight
50
M
Telcolor
Daylight
50
M
PROCESSING: M = films can be processed only by the maker; L = films can be
processed only by an approved laboratory through a photographic dealer: U =
films can be processed by the user by means of special processing kits.
DISPLAYING THE COLOUR PICTURE. The colour transparency can be viewed in a variety of transparency viewers.
The simplest consist of a magnifying glass set in a frame into which the picture can be inserted. If the viewer is held
against a lighted background, the picture appears enlarged and well illuminated. More elaborate viewers have an
artificial light source of their own.
The most satisfactory way is to project the transparency in a projector which will throw a large picture on a screen.
Finally colour enlargements can be made from transparencies. These cannot show the full tonal range and brilliancy
of the projected picture, but are generally acceptable, particularly if the transparency does not show undue contrast
range, is correctly exposed and is sharp.
The colour negative can be printed or enlarged directly on colour paper to produce a colour print of any size.
Alternatively, the colour negatives can be printed on positive transparency film to produce colour transparencies for
viewing or projection in exactly the same way as explained above.
The Technique of Focus
The lens is focused at some definite distance. That means that its position relative to the film Is adjusted In such a
way that whatever is exactly at the focused distance will be represented by a "sharp" image on the film. Everything
else -- everything nearer to the camera or farther from it -- will be, strictly speaking, "unsharp".
In practice the decline of definition is, of course, gradual. Thus there is a zone -- stretching from somewhere in front
of the focused distance to somewhere behind it -- which will appear sufficiently sharp to the human eye. This is
called depth of field.
Now, what should or should not be accepted as sufficiently sharp is debatable. Certain standards, however, have
been agreed upon. It is agreed that any pin-point represented on a 35 mm. negative by a "dot", the diameter of
which does not exceed 1/500 in. or 1/20 mm., should be regarded as sharp. The technical term for this is circle of
confusion.
The limits defined by the circle of confusion vary with the conditions under which the lens is used:
Small apertures yield more depth of field than large ones.
