Yashica Twin Lens Reflex Guide - Focal Press January 1964
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FILMS AND FILTERS
There are two kinds of films available for the Yashica Reflex: black-and-white and colour.
Black-and-white Film
This produces a negative in which the colours and brightness range of the subject are translated into black and white. From
it, prints or enlargements on paper (or, in special cases, black-and-white transparencies) can be made.
The black-and-white film used normally is panchromatic. That means that it is sensitive to all colours There is a choice of
several types differing mainly in sensitivity as well as certain other characteristics.
SLOW FILMS are of low sensitivity, requiring comparatively great exposure. Their main advantage is the extremely fine
grain, permitting a high degree of enlargement without the granular structure becoming. unpleasantly visible. Such films
also yield images of the greatest sharpness. On the other hand, these slow films are not very suitable for coping with fast
movement in other than exceptionally good lighting', nor for general work in poor light. Such films are rated at 40-80
ASA or 17-20 DIN.
MEDIUM SPEED FILMS still yield a reasonably tine grain with good gradation. They are the most suitable material for
all-round photography, other than in poor light. These films are rated at 90-160 ASA or 20-23 DIN.
FAST FILMS with somewhat coarser grain (still acceptable for reasonable degrees of enlargement) will cope with most
light conditions including poor light and interiors in favourable conditions. This is the right film for the photographer who
wants to be prepared for the unusual, to arrest fast movement with high shutter speeds, as welt as shots in poor light. The
speeds are 200-400 ASA or 24-27 DIN.
ULTRA FAST FILMS are primarily intended for high speed sports shots in dull weather, interior snapshots in poor light,
night photography and ill-lit stage pictures. These films are specialist types for conditions where normal materials are
totally inadequate. They should not be used for general photography. The high speed is achieved at some cost in definition
and graininess. Speed ratings range from 500-1600 ASA or 28-33 DIN.
The above speed figures are based on the latest ASA Standard for film speeds (and on the BS and DIN standards under
revision). These figures, when used on the exposure meter, give minimum correct exposures, to make the most of the
versatility of the film and of the image quality. They are also the figures quoted by most film manufacturers. Sometimes
films are, however, still rated according to earlier standards which in effect incorporated a generous safety factor against
underexposure - by the simple process of overexposing films about 100 per cent (well within the exposure latitude of most
black-and-white films). So you may come across films apparently only half as fast as others of similar type, because of
this difference in ratings. The table on p. 70 indicates the current film speeds to be used with the exposure meter, even if
the film packing gives a lower rating.
This applies to black-and- while negative materials only; speed rating methods have not changed for colour films.
There is a wide range or different makes of films in all speeds on the market. Their characteristics, apart from speed, vary
slightly from make to make. It is safe to say that all well-known brands are reliable and good. The best film is the one you
are used to. Professional photographers and advanced amateurs may find one or the other characteristics of a particular
make - i.e., its gradation, granular structure, acutance, etc. - of particular value for specific jobs.
Colour Film
These films produce an image in colour after appropriate processing, corresponding directly or indirectly to the natural
colours of the subject. From the practical point or view, colour film is as easy to use as black-and-white film but needs a
little more care in exposure. Processing is more complex and is often carried out by the film-maker or specially appointed
processing laboratories.
There are two basic types of colour film: reversal and negative.