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but as the film will not require so much
enlargement, with consequent loss of
detail, faster film can therefore be used.
Perhaps a word about film speeds will
not be amiss at this point. Generally
speaking the slower the rated speed of
the film the finer the grain that can be
obtained. Grain is the granular appear-
ance of an image when the film is en-
larged abnormally. If enlarged enough
the small individual grains will become
visible. Fine detail depends on the lack
of graininess of the negative when it has
to be enlarged. Graininess is not an im-
portant factor if the degree of enlarge-
ment is not great.

Speed of a film is not too important
when photographing scenes of crime but
all too often the lighting facilities are
very unsatisfactory and if a fast film can
be used, or a wide aperture on the lens,
the exposure will not have to be painfully
long with the ever present chance of
movement in the camera or the object.

The obvious advantages of photograph-

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BOX 52 -

ing the scene of a crime or of any objects
which might later become exhibits, are
not to be argued. The expense involved
need not be great. An ordinary camera
with readily procurable film can be util-
ized to a good deal of advantage. Involved
processes requiring special apparatus and
film can best be left to the branch
organized for this type of work. The
operation known as powdering a latent
impression (the act of powdering a sur-
face thought to contain an oily deposit
from contact with the patterned area of
some person's finger, palm or foot) may,
unless done properly, ruin the impression
for any further use. Chemicals, moulage,
ete., sometimes have an effect on the
object being checked. Once a thing is
photographed, however, a record is ob-
tained that is irrefutable, and yet the
action in no way prevents, or interferes
with, the further use of a scene or an
object. Should any technique, applied for
the purposes of investigation, mar or dis-
figure the exhibit, or in any way change

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its characteristics, the photograph will
remain to show its original condition and
appearance. The fact that the photograph
may not be used in an evidentiary capacity
is of little moment. Prosecutions some-
times drag on for months, and even years,
and photographs refresh the memory as
no other medium can. In addition, they
form an excellent illustrative subsidiary
to the investigator’s notes and reports.

Finally, processing can usually be
farmed out to any local photographic
studio, and as long as the officer con-
cerned is present when the processing is

carried out, the continuance of possession

is complete. It would be as well for the
investigator to have the various stages of
development of the photograph, explained
to him as they are being done, so that
he has a working knowledge of the results
obtained, and he will be in a position to
answer questions intelligently, if required.

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