An Improved Photographic Shutter.
Year: 1896

page_text: Date of Application, 22nd June, 1896
Complete Specification Left, 15th Mar., 1897-Accented. 19th June 1897
PROVISIONAL SPECIFICATION.
An Improved Photographic Shutter.
We, WILLIAM THOMSON of The Royal Institution Laboratory Manchester,
Consulting and Analytical Chemist and HARRY SMITH 33 Withington Road
Whalley Range Manchester Chemist do hereby declare the nature of this invention
to be as follows:-
Our invention consists of an improved photographic shutter by means of which
plates may be exposed so that the foreground of the photograph receives a longer
exposure than the middle-distance, and still longer than the far-distance or sky.
We. achieve this by a special arrangement of a roller blind and by means of a
special form of release we can make the exposure either instantaneous or for
time by a slight or by a firm pressure of the pneumatic ball respectively. We
also apply this special form of release to the shutter arranged on the plan of
giving each part of the picture the same amount of exposure on the "blind"
principle.
In the case of the first arrangement (giving extra exposure to the foreground)
we make the shutter as follows:-
We take a blind of macintosh cloth or other flexible light proof material and a
shutter box arranged to fit on the front of the lens tube with a roller at the top
and bottom. The bottom roller is a hollow barrel containing a spiral spring
which is attached to a spindle passing along the interior of the barrel in the usual
way of making shutters on the roller blind principle. The lower end of the blind
is attached to the barrel and a square or oblong opening is made in the blind thus
producing the effect of attaching the blind by two narrow tapes one at each end of
the barrel; the blind passes up the inside of the back of the shutter over the loose
top roller and down the inside of the front of the shutter, the other end of the
blind is also attached to the barrel by two similar tapes or strings which wind on
to the barrel in the reverse direction to the tapes at the other end os the blind, so
that the tapes at the one end of the blind wind on to the barrel as the tapes at the
other end unwind from the barrel. A pulley is fixed at the end of the barrel
and fitted with a cord which passes through the bottom of the shutter case to the
outside.
In using the shutter the cord is pulled and thus drawn off the pulley on which it
was coiled: this coils up the interior spring and simultaneously draws the blind up
the back and down the front of the shutter closing the opening when it is desired
to make an exposure the barrel is released as described below, and the tapes of the
blind wrap on to it thus moving the blind upwards from the front and downwards
at the back, the exposure thus commences from below and closes from above,
thus when the blind is exactly doubled over the top roller the whole opening in
the shutter is uncovered, and when it passes over the top roller it commences to
close, and is closed on completely passing over the top roller. As soon as the
barrel has made one revolution the blind has completed half its journey and is then
half way over the top roller. In this position the shutter is completely open, but
the blind passes from above downwards so that the foreground is the last to be
closed to the light.
The tension upon the spring in the barrel is increased in the usual way by means
of a knob on the spindle controlled by a clutch on the outside of the shutter box.
The other end of the barrel is closed by a disc to the centre of which is attached

page_text: a smaller cylinder or axle which projects through the side of the box, and on which
is fixed at right angles a brass pin. The end of a long flat brass strip or spring is
fixed near the top of the side of the shutter box, the free end terminating in a two
pronged fork at the projecting end of the barrel so that the outer of the two
prongs' chamfered off towards the side which meets. the revolving projecting pin in
setting the shutter will engage the pin which projects at right angles from the axle
of the barrel. A pneumatic india-rubber bulb, tube, and ball which arrangement
is well known, are so arranged that when the ball is pressed gently the spring is
lifted by the bulb expanding, and the pin on the axle of the barrel slips between
the two prongs of the fork and makes an instantaneous exposure, by two revolutions
of the barrel. If it be desired to make a time exposure the spring must be raised
higher by making a firmer pressure on the rubber ball so that when the barrel has
made one revolution which completely opens the shutter the pin is caught by the
inner prong of the fork, and when the pressure on the ball is released the spring
falls and the pin again slips between the prongs of the fork, and completes the
second revolution which closes the shutter. The height to which the spring shall
rise for a time exposure is controlled by a brass check or bridge either fixed to the
shutter box across the spring near the fork i.e. below the rubber bulb which raises
the spring or by some similar device.
We also make a shutter in which the foreground and distance receive an
exposure of equal duration and in this case the blind simply unwraps from the
bottom barrel which contains the spiral spring and is drawn up on to the top roller
returning when the release is effected. In this case we prefer to make the axle of
the upper roller to project instead of the axle of the barrel as above described, and
we reverse the position of the spring with the two prongs which in this case control,
the top roller, and we also fix the pulley and cord on the top roller instead of the"
barrel as described for the foreground shutter.
Dated this 19th day of June 1896.
WILLIAM THOMSON.
HARRY SMITH.
An Improved Photographic Shutter.
WILLIAM THOMSON of The Royal Institution Laboratory of Manchester in the
County of Lancaster, Analytical Chemist and HARRY SMITH of 33 Withington
Road, Whalley Range Manchester in the County of Lancaster, Cheinist do hereby
declare the nature of this invention and in what, manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
Our invention consists of an improved photographic shutter by means of which
plates may be exposed so that the foreground of the photograph receives a longer
exposure than the middle distance and still longer than the far distance or sky.
We achieve this by a special arrangement of a roller blind, and by means of
a special form of release we can make the exposure either instantaneous or for
time by a slight or by a firm pressure of the pneumatic ball respectively. We
also apply this special form of release to the shutter arranged on the plan of
giving each part of the picture the same amount of exposure on the blind
principle.
In the case of the first arrangement (giving extra exposure to the foreground)
we make the shutter as follows:-
We take a blind of macintosh cloth or other flexible light proof material A
and a shutter box B arranged to fit on the front of the lens tube with a roller at

page_text: the top and bottom. The bottom roller C is a hollow barrel containing a spiral
spring which is attached to a spindle passing along the interior of the barrel in the
usual way of making shutters on the roller blind principle. The lower end of the
blind is attached to the barrel and a square or oblong opening is made in the blind
thus producing the effect of attaching the blind by two narrow tapes or cords, one
at each end of the barrel; the blind passes up the inside of the back of the shutter
over the loose top roller, and down the inside of the front of the shutter, the other
end of the blind is also attached to the barrel by two similar tapes or strings which
wind on to the barrel in the reverse direction to the tapes at the other end of the
blind, so that the tapes at the one end of the blind wind on to the barrel as the
tapes at the other end unwind from the barrel. A pulley D is fixed at the end of
the barrel, and fitted with a cord which passes through the bottom of the shutter
case to the outside.
In using the shutter the cord is pulled and thus drawn off the pulley on which it
was coiled, this coils up the interior spring and simultaneously draws the blind up
the back and down the front of the shutter closing the opening: when it is desired
to make an exposure the barrel is released as described below, and the tapes of the
blind wrap on to it thus moving the blind upwards from the front and downwards at
the back, the exposure thus commences from below and closes from above, thus when
the blind is exactly doubled over the top roller as shown at E the whole opening in the
shutter is uncovered 'and when it passes over the top roller it commences to close,
aud is closed on completely passing over the top roller. As soon as the barrel has
made one revolution the blind has completed half its journey and is then half way
over the top roller. In this position the shutter is completely open but the blind
passes from above downwards so that the foreground is the last to be closed to
the light.
The tension upon the spring in the barrel is increased in the usual way by means
of a knob F on the spindle controlled by a clutch on the side of the shutter box.
The other end of the barrel is closed by a disc to the centre of which is attached a
smaller cylinder or axle which projects through the side of the box and on which
is fixed at, right angles a brass pin G. The end of a long flat brass strip or
spring H is fixed near the top of the side of the shutter box the free end terminating
in a two pronged fork J at the projecting end of the barrel so that the outer of the
two prongs chamfered off towards the side which meets the revolving projecting"
pin G in setting the shutter will engage the pin G which projects at right angles
from the axle of the barrel. A pneumatic indiarubber bulb, tube, and ball K,
which arrangement is well known, are so arranged that when the ball is pressed
gently the spring is lifted by the bulb expanding and the pin on the axle of the
barrel slips between the two prongs of the fork and makes an instantaneous
exposure by two revolutions of the barrel. If it be desired to make a time exposure
the spring must be raised bigher by making a firmer pressure on the rubber ball
so that when the barrel has made one revolution which completely opens the
shutter the pin is caught by the inner prong of the fork, and when the pressure on
the ball is released the spring falls and the pin again slips between the prongs of
the fork, and completes the second revolution which closes the shutter. The
height to which the spring shall rise for a time exposure is controlled by a
brass check L or bridge either fixed to the shutter box across the spring near
the fork i.e. below the rubber bulb which raises the spring or by some similar
device.
We also make a shutter in which the foreground and distance receive an
exposure of equal duration and in this case the blind simply unwraps from the
botton barrel which contains the spiral spring and is drawn up on to the top roller
returning when the release is effected.. In this case we prefer to make the axle of
the upper roller to project instead of the axle of the barrel as above described, and
we reverse the position of the spring with the two prongs which in this case control
the top roller and we also fix the pulley and cord on the top roller instead of the
barrel as described for the foreground shutter.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner, the same is to be performed, we declare that what we
claim is :-
(1.) The use of a spring made by fixing a flat straight piece of brass or other
metal at one end to the side of the shutter it being free at the other end with a
short two pronged fork at the free end, against one prong of which a small brass
pin projecting at right angles from the end of the axle of the top free roller rests,
when the shutter has been set by drawing the blind on to the top free roller, or
similar devices arranged upon the above mentioned fork principle; the rubber
bulb resting between the side of the shutter and the spring near the free end on
being inflated by pressing the pneumatic ball pushes the free end of the spring
away from the side of the shutter thus releasing the pin which had been resting on
one prong of the fork and thus making an instantaneous exposure, or if wanted for
time exposure a firm and quick movement of the pneumatic ball pushes the spring
as far as it will go up to the head of a nail which passes through a hole in the
spring arranged to prevent the spring from being pushed out too far beyond the
point at which the second prong of the fork will engage the projecting pin in
making one revolution. In this way the pin after being released from one prong
of the fork is arrested by the second prong leaving the shutter full open, and when
the pressure is removed from the ball the air in the bulb is, released, and the fork
falls into its original position, the projecting pin allowing the second revolution of
the roller to take place and the shutter to close completely, the opening and
closing of the shutter being made by two revolutions of the top roller.
(2.) The employment of a blind made about the same length as the shutter which
rises from the back, passes over the top roller, and closes from the front or vice versa,
thus giving the foreground a greater exposure than the middle distance, or sky in
landscape work on the principle above set forth.
Dated this the 13th day of March 1897.
WILLIAM THOMSON.
HARRY SMITH.