Page 22 - 2015-06

shire. He reasoned that the quality of 16mm tions of 35 mm standard size set either side just
S.O.F. would be considerably improved if 35 inside the 3 mm margin reserved for the sound
mm sound tracks could be directly contact tracks. Then two 8 mm spaces for the 16mm
printed, full size, on to 16mm picture prints, frame heights plus the 2.75 mm perforations
and then run, during projection at the correct equal the 18.75 mm of a 35 mm frame. This
linear speed for 35 mm sound tracks of 18 resulted in the format shown in Fig 1. At a later
inches per second. This is more than twice the stage of development this format was modified
speed of 16 mm S.O.F. and left the problem of slightly to accommodate a third centrally
how to marry the 16 mm picture speed of 7.2 placed sprocket hole. Fig 2. This was apparent-
inches per second with the 35 mm sound track ly to ease the strain on the film now travelling
speed of 18 inches per second on the one strip at the higher speed of 18" per second. (Remem-
of 16 min film. ber that in the 1930s much tri-acetate film was
liable to become
Harper's solu- brittle and crack
tion to this and much devel-
problem was to opment was be-
design a special ing carried out by
dual-purpose the manufactur-
film printer for ers to improve its
which he ob- flexibility and
tained a British long term charac-
Patent Specifi- teristics).
cation No.
509009 for Harper designed
which he ap- a new film perfo-
plied on Janu- rator Ref.4 to
ary 4th 1938. produce this new
The complete type of 16 mm
specification film stock but
was left on May this is not men-
th
14 1938 and tioned in the Pat-
accepted on Ju- ent Specification.
ly 4 th 1939. In order to obtain
Ref.3. his special 16
To achieve his mm projection
aim the area prints Harper de-
available on 16 signed a special
mm had to be and rather com-
reallocated. plicated dual
Edge perfora- purpose printer.
tions were no This is described
longer used,
in great detail in
three millime- the full Patent
tres each side of Specification and is too lengthy and involved to
the film were reserved for sound tracks leaving
reproduce here. On the first run through the
10 mm in the centre for the width of the 16 mm printer the optical sound track of the 35 mm
picture frame. The height of a 35 mm picture film was held in intimate contact with one of
frame is 18.75 mm and this was divided as
the 3 mm wide tracks on the 16mm print stock.
follows: - 2.75 mm was utilised by two perfora-
A second print run was then undertaken where-
22 REEL DEALS June 2015