A New or Improved Instantaneous Shutter for Photographic Cameras.
Year: 1886

page_text: Date of Application, 6th Oct., 1886.
Complete Left, 4th July, 1887.
Complete Accepted, 30th Aug., 1887.
PROVISIONAL SPECIFICATION.
A New or Improved Instantaneous Shutter for Photographic
Cameras.
I, JOHN LEISK, of 169 Commercial Street, Lerwick, Shetland, Merchant, do
hereby declare the nature of my invention, to be as follows:-
My invention relates to a new or improved construction and arrangement of
instantaneous acting shutter to be applied to photographic cameras, and has for its
object to give separate exposures to the foreground and sky in a landscape on the
same negative plate; the foreground exposure being long enough to give full details
of moving objects, while the sky exposure would be short enough to print clouds very
distinctly, or shade the sky darker towards the zenith, as in nature. All in contra-
distinction to giving the same exposure both for the foreground and sky, with the
shutters heretofore used in photographic cameras.
And the nature and novelty of my invention consist in constructing the shutter of
two separate discs of wood, metal, or other material. The one, a stationary disc, is
formed with an eccentric circular aperture corresponding in size with the largest
working aperture of the lens used, with which it is set in a concentric line; while the
other, which is a rotating disc, is formed with an eccentric segmental winged aperture,
or segmental circular opening with two curved open projections, one on either side, to
give three different stages of exposure during an oscillation of the disc on its eccentric
centre, coinciding with that of the fixed disc.
Thus the upper segment of the aperture in this moving disc coincides with the upper
segment of the round aperture in the stationary disc and aperture of lens. Then from
the eccentric centre of the oscillating disc, which may be a radius or more vertically
down from the circular aperture in the fixed disc, a circle is drawn through the centre
of this aperture for the outer circumference of the winged part of the aperture on
either side in the oscillating disc, and another circle is drawn from the lower diameter
of the aperture for the inner circumference of these winged apertures.

page_text: A centre is taken in the circumference of the outer wings with a radius equal to the
radius of the central aperture, and the ends of the segmental winged apertures are
drawn forming the said segmental winged aperture coinciding with the circumference
of the central aperture.
My improved shutter constructed as described, can be applied either to the front or
back of the lens of a photographic camera.
In applying it to the former, I secure a block or tube, with a projecting piece on its
lower side round the hood or front of the lens, to which I attach the stationary disc of
the shutter, with its eccentric round aperture in line with the working aperture of the
lens. The oscillating disc part of the shutter is mounted on its centre in front of the
stationary dise, on an arbour or spindle which passes through the latter and through
the projecting block. A coiled spring is by one arrangement fitted round this spindle,
preferably within the oscillating disc keyed to the spindle; the outer end of the spring
being attached to the oscillating disc, and this spring wound up by turning by hand
the milled head of the spindle; and a ratchet wheel is mounted on the spindle at its
inner end, controlled by a movable detent for tightening up the spring and regulating
the speed of the rotating shutter disc. A metal rim is preferably mounted round the
outer surface of the stationary disc, and projects slightly beyond the edge surface of
the oscillating disc to cover and prevent any light entering the lens between these
discs, and this stationary disc may carry a trigger and stop for making the exposure.
When a photograph of a landscape is to be taken by the camera, the action of the
instantaneous shutter is as follows:-The coiled spring is wound up on its spindle
until the required tension according to the rapidity required is obtained (or if the
spring be wound up it may he let down by loosening the detent). The revolving disc
is then turned round by hand by means of a stud on front of it till the centre of the
winged aperture corresponds with that of the lens and is there retained by the said
trigger for foccussing. That accomplished, it is turned further round so as to close
the lens and is there held by the trigger. To make the exposure the trigger is
withdrawn and the movable disc makes an oscillation or rotation, during which the
inner open winged part of the latter coincides with and passes the lower part of the
apertures of the stationary disc and of the lens, and thus a negative of the landscape
is taken in which three different phases of exposure are obtained, the foreground
exposure being about three times that of the sky, so that the former is fully exposed
and takes in all moving objects, while the sky is not over exposed and prints clouds
very distinctly, and should no clouds be visible it shades the sky darker towards the
zenith as in nature. Other equivalent arrangements of springs or weights than that
of the spiral spring described might be adopted for rotating the moving winged disc
at any desired speed.
Dated thin th d...
Ostaba 100%

page_text: A NEW or improved Instalater for purc
Cameras.
I JOHN LEISK of 169 Commercial Street, Lerwick Shetland Merchant, 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 :-
My Invention relates to an improved instantaneous shutter for out-door photo-
graphy whereby the exposure of the parts of the picture corresponding to the
foreground and sky, will be of different duration as required by the different degree
of illumination of the parts of the subject, the exposure to the foreground being long
enough to obtain full details thereof, and the exposure to the sky being short enough
to photograph clouds (if any) distinctly and so graduated as to shade the sky darker
towards the zenith, as in nature.
This result is obtained by the peculiar form of the aperture of the shutter, which
I will proceed to describe with reference to the accompanying drawings wherein
figure 1 represents a front elevation; figure 2 a vertical central section; figure 3 a
back elevation; and figure 4 a front elevation shewing the shutter in two positions.
The same letters of reference indicate the same parts in all the figures.
The shutter is in the usual form of a disc A revolving in front of and covering the
lens aperture and provided with an aperture which in the course of the disc's
revolution, passes over the said aperture and uncovers the upper and lower portions
thereof for different periods of time. The disc A is preferably made of ebonite and it
revolves on a centre a carried by a stationary disc B provided with an aperture and
flange B' corresponding to and fitting on the lens tube in the usual manner, and with
a circumferential flange B2 enclosing the edge of the disc A and preventing access of
light between the discs A and B. The shutter A is actuated by a spring contained in
a barrel at back of disc B and whose tension is adjustable by a pawl and ratchet
motion, all as usual, and which it is therefore unnecessary to describe.
The revolving shutter A is retained in the position in which it is set previous to
exposure by a pin c engaging, as shewn in figure 1, with the ordinary pneumatically-
worked trigger or lever & mounted on the flange of the fixed disc B and its motion is
checked after its aperture has passed over the lens aperture by a spring e also fixed on
the flange of disc B in such position that it also serves to prevent rebound of the
shutter. The shutter is further provided with an adjustable radial bolt f terminating
in a nib f in whose path of revolution (when the bolt is pushed out more or less)
stands a stop formed by an inwardly bent lug d' on the trigger whereby the shutter
will be held in such position, shewn in figures 1 and 2, that the full aperture of the
lens will be uncovered for focussing or for giving a prolonged exposure. When the
bolt is retracted, it passes clear of the stop.
The preferred form of the aperture, which constitutes the essential feature of
this invention is clearly shewn and is constituted by a semi circular portion 1, 2, 3,

page_text: corresponding to the upper half of the lens aperture and by ane longated portion 4, 5,
6, 7, 8, in the form of a segment of an annulus concentric with the centre of
revolution a of the shutter, and whose outer and inner radii are respectively equal to
about the distance of the centre of the lens aperture and the least distance of the
circumference of the lens aperture, from the centre a. The ends of this elongated
part of the aperture are preferably in the form of arcs 4-5-7-8, struck from points
on the outer circumference 1-8-3-4 of the annulus, at the distance of the inner
circumference thereof.
The relative proportions of the respective portions 1, 2, 3, and 4, 5, 6, 7, 8, of the
aperture are such that the exposure of the lower half of the lens aperture corre-
sponding to the foreground of the picture, will be three times as long as that of the
upper part corresponding to the sky, which is about the best proportion but I do not
limit myself to such proportion nor to the particular form of the aperture herein
described, as it is evident that this may be varied in outline, so as to give a differential
degree of exposure to the upper and lower portions of the picture.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, I declare that what I claim is ;-
A photographic lens shutter having an aperture of such form as to uncover the
upper and lower halves of the lens aperture for different periods of time, so as to give
different periods of exposure to the foreground and sky of the picture, substantially
-as specified.