and Duration of Exposure in Photographic Apparatus.
Year: 1885

page_text: and Duration of Exposure in Photographic Apparatus.
I CHARLES JAMES WOLLASTON of 16 Philpot Lane in the City of London
Gentleman do hereby declare the nature of my said Invention for "IMPROVED
MEANS FOR CONTROLLING AND REGULATING THE MANNER AND DURATION OF
EXPOSURE IN PHOTOGRAPHIC APPARATUS to be as follows:-
My Invention has for its principal object to provide means whereby the
admission of the rays of light through the lenses used with Photographic cameras
and the shutting of the said rays out therefrom can be effected in a more efficient
manner and with less liability to jarring and shaking during the period of
exposure than in apparatus hitherto used for this purpose.
According to my Invention I provide two segmental or circular pieces each with
an opening in it and with solid portions on either side of this opening. These
segmental or circular pieces are mounted so that they move upon a centre in such
a manner that the continuation of the motion in the same direction both admits
and afterwards shuts out the light. The two segmental or circular pieces are
provided so that as one is moved in one direction and the other in the other
direction the exposure is made commencing at the centre of the lens and opening
outwards towards the sides by a continuation of the movements in the same
directions and the exposure is terminated by closing from the sides towards the
centre the portions of the pieces at the sides of the openings opposite to the sides
which formed the obstruction to light before exposure forming the obstruction to
light after exposure. The jarring or shaking due to changing of motion from one
direction for opening to another for closing is by this arrangement obviated.
I arrange the aforesaid pieces preferably so that they enter slots in the opposite
sides of the lens tube the said tube not being severed so that in the case of double
lenses between which the segmental or circular pieces are inserted the lenses can
be properly adjusted without afterwards being disturbed in their parallelisin or
relative positions.
I prefer to use two segmental or circular pieces as described to secure an opening
from the centre although it will be understood that one piece arranged as described
will give the advantage of opening before and closing after exposure by one
continuous movement.

page_text: I may operate the said pieces in any suitable way such for example as by
causing them to drop by gravity or I may connect them to a lever operated by a
spring so that on releasing the spring the said pieces are caused to travel over the
field, the rate at which they travel and consequently the time of exposure being
regulated by a brake pressing upon a disc connected with the said spring or against
other moving part of the apparatus. I make use of the ordinary diaphragms with
openings in them of various sizes or I use a segmental or circular piece resembling
one of those hereinbefore described the various sized openings being made in the
said piece in a circle or the arc of a circle described from the centre upon which
the said piece turns which centre may be the same as that upon which the aforesaid
segmental or circular pieces turn.
By means of a Bange with a suitable screw I am enabled to fit my apparatus in
its complete form including lenses and diaphragms to any photographic camera as
ordinarily arranged.
The mounting of the lenses at each end of the tube or mount as described
affords a ready means by using suitable "adapters" or fitting pieces for substituting
one lens for another and so utilizing the same shutter apparatus for lenses of
various foci.
I arrange the lens tubes or mounts so that I can readily remove one mount with
its lenses and substitute another mount with other lenses.

page_text: and Duration of Exposure in Photographic Apparatus.
I CHARLTON JAMES WOLLASTON of 16 Philpot Lane in the City of London
Gentleman 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 has for its principal object to provide means whereby the
admission of the rays of light through the lenses used with Photographic cameras
and the shutting of the said rays out therefrom can be effected in a more effectual
manner and with less liability to jarring and shaking during the period of exposure
than in apparatus hitherto used for this purpose. According to my Invention
I provide a slide or slides which turn upon a centre to open and close the passago
for light through the lenses and I provide means in connection therewith by
which the time of oposure may be regulated. I will describe my Invention
with reference to the accompanying drawing whereon Figures 1, 2 and 3 represent
a front elevation a back elevation and an edge view respectively of Photographic
shutter provided with apparatus according to my Invention. The remaining
Figures represent modifications and details as hereinafter described.
According to the arrangement of my Invention shewn in Figures 1, 2 and 3
I provide two segmental or circular pieces A each having an opening B therein of
any desired shape but which I prefer to make of an elongated form as shewn in
Figure 4 and with solid portions on either side of this opening as at a a¹. These
segmental or circular pieces A are mounted upon a centre C so that they move in
such a manner that the continuation of the motion in the same direction both
admits and afterwards shuts out the light. As the two segmental or circular
pieces A move in opposite directions as indicated by the arrows in Figure 1 the
exposure is made to commence at the centre of the lens and to open outwards by a
continuation of the movements towards the sides in the same directions and the
exposure is terminated by the blank parts a of the pieces A closing upon each
other from the sides towards the centre as shewn by the dotted lines in Figure 1.
The blank or solid portions a of the pieces A at the sides of the openings opposite
to the blank or solid portions a. which formed the obstruction to light before
exposure forms the obstruction to light after exposure as shewn by full lines in
figure 1. The pieces A are maintained in the position shewn by the dotted lines
by any suitable or ordinary trigger arrangement which when released allows the
pieces A to resume their normal positions shewn by the full lines in Figure 1. The
jarring or shaking due to change of motion from one direction for opening to
another for closing is by this arrangement obviated.
I arrange the pieces A preferably so that they enter at the opposite sides of the
lens tube D the said tube not requiring to be severed but being capable of being
made metallically continuous through the shutter so that in the case of double

page_text: lenses between which the segmental or circular pieces A are inserted the lenses can
be properly adjusted without afterwards being disturbed in their parallelism or
relative positions.
I use two segmental or circular pieces as described and shewn in Figure 1 to
secure an opening from the centre although it will be understood that one piece A
Having an elongated opening as shewn in Figure 5 will give the advantage of
opening before and closing after exposure by one continuous movement.
I may operate the pieces A in any suitable way such for example as by
causing them to drop by gravity but I prefer to connect them to a disc E by a
lever or arm F as shewn operated by a spiral spring E so that upon releasing the
spring G after it has been contracted in setting the pieces A the said pieces are
caused to travel over the field back to their normal positions. To regulate the
rate at which they travel back and consequently the time of exposure I provide
a brake block or pad I caused to press upon the discs E with the necessary degree
of pressure which may be adjusted as required by the screw K. The brake block
or pad I is carried on the end of a spring blade L between which and the adjusting
screw K is another spring plate M which may be a continuation of the blade L
turned thereunder. By this arrangement the pressure upon the disc E may be
adjusted to the greatest nicety and the pieces A allowed to return to their normal
position at any required speed according to the required duration of exposure the
motion of the said pieces being uniform and without jerks or jars. I may make
use of the ordinary diaphragm with openings as shewn in Figure 6 in them of
various sizes or I may use a segmental or circular piece N as shewn in Figure 2
the various sized openings therein being made in a circle or in the arc of a circle
described from the centre C upon which the said piece and also the pieces A may
turn or if desired it may be made to turn on a separate centre of its own O, as
shown. P is a spring detent for retaining the piece N in its adjusted position by
engaging one or other of a series of notches c. This circular diaphragm may be
used with photographic shutters of ordinary construction.
By means of a flange piece R provided with a suitable screw thread and means
for securing it to an ordinary camera I am enabled to fit my apparatus in its
complete form including lenses and diaphragms to any photographic camera as
ordinarily arranged.
The mounting of the lenses at each end of the tube or mount as hereinbefore
described affords a ready means by using suitable "adapters" or fitting pieces as
shewn at Q in Figure 3 for substituting one lens for another and so utilizing the
same shutter apparatus for lenses of various foci.
The apparatus constructed is contained in any suitable shutter or case suited to
the camera with which it is used and the buttons or other parts by which the
apparatus is manipulated project to the exterior of the said shutter or case.
Having now particularly described and ascertained the nature of this Invention
and in what manner the same is to be performed I declare that what I claim is
First. For effecting exposure in Photographic apparatus a slide or piece or slides
or pieces for opening and closing the passage for light into the camera by one
continuous movement in the same circular direction substantially as herein before
described.
Second. For effecting exposure in Photographic apparatus a piece or slide
pieces or slides for opening and closing the passage for light into the camera it or
they being mounted to turn upon a centre and to pass through the opposite sides
of the lense tube or mount between the lenses therein substantially in the manner
and for the purpose hereinbefore described.
Third. The circular or rotatory diaphragm arranged to operate from a centre
and to pass through openings in the lense tube and the combination of such a
diaphragm with the subject matter of my preceding claims all substantially as
hereinbefore described.

page_text: Fourth. In Photographic apparatus of the kind described the combination of
a spring and arms or connections for operating the rotative piece or pieces which
open and close the passage for light into the camera substantially as bereinbefore
described.
Fifth. In Photographic apparatus a shutter containing the mechanism for
opening and closing or controlling and regulating the passage of light into the
camera so that the said mechanism operates between the lenses without necessitating
severance of the tube or mount substantially as hereinbefore described.
Sixth. The brake or controlling and regulating mechanism for controlling and
regulating the duration of exposure in photographic apparatus substantially as
hereinbefore described.
Seventh. Mechanism for regulating and controlling the duration of exposure in
photographic apparatus consisting of the combination of a rotative piece or pieces
for opening and closing the passage for light into the camera and a brake for
regulating the motion and speed thereof substantially as hereinbefore described.
Deted this 2nd der of December 1883
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, London, W.C.,
Agent.