Improvements in Photographic Cameras and Parts thereof.
Year: 1890

page_text: Date of Application, 19th July, 1890
Complete Specification Left, 20th Apr., 1891-Accepted, 23rd May, 1891
PROVISIONAL SPECIFICATION.
Improvements in Photographic Cameras and Parts thereof.
I, JOHN EDWARD THORNTON, of 3, New Lorne Street, Moss Side, Manchester
in the County of Lancaster, Manufacturer, do hereby declare the nature of this
invention to be as follows:-
The improvements forming the subject of this invention relate to photographic
cameras and parts thereof, and particularly to that class in which the various parts
such as the lenses, shutters, finders, and, sensitive-surface carriers are all combined
to form what is generally styled a "hand camera." The object of this invention is
to make such apparatus compact, portable, and light, and by means of improved
construction and arrangement of the parts to make it equally useful as a hand or field
camera, and so that it may be quickly adapted to any requirements.
A camera constructed according to my invention combines many of the advantages
of both the ordinary hand cameras and the larger field cameras also. It may be used
in the hand, or upon any suitable stand, either for instantaneous or prolonged
exposures, and with lenses of various foci, and is therefore suitable for various kinds
of work. The shutter is selfcapping so that the sensitive surface does not need
covering whilst the shutter is being set; the finder shows the picture of the same
size that will appear on the negative, and the picture is projected upon the finder
screen by the same lens that projects it upon the sensitive surface, and may therefore
be focussed accurately without the need of graduated scales, or guesswork.
The sensitive surface may be easily and quickly changed and may be placed
vertical and parallel with the vertical lines of the object to be photographed,
whenever it is found necessary to tilt the camera.
In constructing a camera according to this invention I use a rectangular box or
case, at one end of which I place the optical system, and at the other end the
sensitive surfaces. The latter may be contained in the ordinary plate-holders or in a
suitable magazine as preferred; or a sensitive web may be used in connection with
a system of rollers as in the ordinary roller slide; but in any case the sensitive
surface after exposure may be changed for a fresh one without opening the case.
The frame or carrier which holds the sensitive surface may be pivoted centrally
like an ordinary central-swing back and for the same purpose. An index outside
the case and moving with the carrier serves to show the position of the carrier and
sensitive surface inside, and has suitable means (which may be a screw rack and
pinion, or other arrangement) for moving and clamping the carrier when desired.
A swinging plumb or pointer outside the case serves to show whether the interior
carrier is perpendicular or not.
One end of the box or case is capable of extension to various distances by means
of an inner or outer sliding case, framework, rods, wings or other devices and
suitable clamping arrangements.
The kind of lens I prefer to use is one of the doublet or rapid rectilinear class,
and of short focus (say 4 or 5 inches for plate pictures), with a large working
aperture. I mount one of the combinations of the lens (either the front or back
one, but preferably the front) on a moveable plate (either sliding swivelling, or
revolving) so that the aforesaid lens combination may be moved out of the path of
the light rays which pass through the lens; thus the other combination would
produce a single lens of longer focus.
If desired two or more lenses may be mounted upon a moveable plate in a similar
manner; or two sets of single lenses carried by two moveable plates, one in front of
the other may be used to produce doublet lenses of various foci; or several single

page_text: lenses may be used with a corrector to prevent distortion of the marginal lines of
the picture.
The diaphragms may be of the well-known "Iris" form, or simply holes formed
in a moveable plate. The ratio of the stop in use, to the focus of the lens is
indicated on a scale outside the camera; this scale is made moveable and is
automatically shifted whenever the lens is changed for one of different focus, and
the ratio of the same stop to the other lens is indicated. Thus one set of stops
only is required. Instead of a moveable scale I may use a fixed one with a moveable
perforated cover to answer the same purpose.
When the extension part is drawn out, a lock or catch engages with it to hold it
in position; and I prefer to arrange this lock so that the part cannot be extended
until the lens has been changed for the longer one, or vice vers 1.
For focussing purposes the whole optical system may be mounted within the box
upon a travelling carriage operated in any suitable manner; or it may be rigidly
fixed therein and the necessary focussing adjustment obtained by the extension
arrangement.
The focussing devices may be provided with the usual graduated scale and index
of distances, but I prefer to use the finder for the purpose of obtaining a correct
and sharp focus, in addition to using it for composing the picture and finding the
principal objects to be photographed.
The finder consists essentially of a mirror placed in front of the sensitive
surface at a suitable angle to project the picture upon a screen in the top or
side of the camera, which is done by the same lens that is used to take the
picture. The two images are therefore identical. When the picture has been
focussed the screen aperture is covered, so as to make the camera light-tight,
and the mirror moved from before the sensitive surface ready for exposure.
The mirror has hitherto been made of silvered glass, and in some cameras
the sudden movement of the heavy mirror immediately before the exposure causes
a vibration of the whole apparatus and consequent blurring of the picture. To
obviate this defect I use transparent silvered celluloid, mica, or other suitable
light material, which may be mounted in the usual way.
By preference I employ a flexible reflector or mirror of the above material
which may be wound upon a spring or other form of roller, so as to be drawn
down in front of the sensitive surface when required and afterward rolled up
again before exposure. I may also use semi-transparent celluloid or mica upon
which to project the image instead of the usual ground glass screen, or it may
be received direct upon the reflector instead. By suitable connections either the
mirror or finder screen can be inclined from their normal position whenever the
sensitive surface is inclined so that both work in unison.
The shutter is made self-capping so that there is no necessity for covering
the lens by a separate movement when re-setting the shutter for another exposure,
and may be constructed in several ways to effect this purpose. The form I
prefer to use is that of the roller blind.
It may consist of an endless flexible blind placed to work either before or
behind the lens, or between the combinations thereof, or in front of the sensitive
surface. It may be passed round two or more flanged guiding rollers, and
prevented from slipping by spikes or points thereon which pierce the blind at
its edges, or by additional rollers revolving in frictional contact or both in com-
bination. The blind may be driven by attaching springs or rubber bands thereto
so as to pull it forward the requisite distance; but I prefer to drive it by
turning one or more of the rollers by springs or other suitable means.
end of one or more rollers is provided with stops engaging with a suitable
detent or release, so arranged that it may stop the blind when it has travelled
far enough to open and close the lens instantaneously, or detain the blind
so that the lens-aperture may remain uncovered for any desired period of time.
If the roller has to make more than one revolution for the requisite travel of
the blind, the stops may be placed upon a wheel gearing into a pinion on the
The

page_text: end of roller (as described in a patent granted to me and numbered 12,238
September 26, 1886) or upon a rack gearing into the said pinion; or upon an
endless chain or cord turning with the roller; or upon a sliding nut or lever
arranged to travel laterally by a worm on the end of said roller; or by stops
fixed to the blind itself; or in any other convenient manner which shall effect
the stopping of the blind in the proper place.
A blind operated in the manner hereinbefore described may be placed so as to
pass behind and in front of the lens and completely round it; or in front of or
behind the sensitive surface, and in front of or behind the lens; or it may be con-
nected to or form a part of the blind which covers the finder screen or a part of
the flexible reflector, or of both combined.
By another system, instead of using an endless blind to avoid the necessity of
covering the sensitive surface each time the shutter is set, I employ a single roller
blind shutter, somewhat after the usual well-known form but add an auxiliary one
which I call the capping blind. This is arranged so that it shall connect to and
wind up with the main shutter blind whilst it is being set, and immediately afterwards
disconnect itself and spring back leaving the lens covered by the shutter blind
ready for exposure.
Another system consists of two separate spring blinds in close proximity, both
winding on to separate sets of rollers like two single blind shutters placed face to
face. Each blind has an aperture cut therein at one end whilst the other part is
solid. After being wound up ready for exposure one blind is released to uncover
the lens aperture, after which the other is released to close it. The winding up of
the blinds may be done by turning the projecting ends of each roller; or by pulling
endless cords passing over or around same; or by cords which wind on to loose
pulleys on the roller shafts and are provided with running clicks and rachets to turn
the rollers when the cords are drawn off, and with or without springs to rewind the
cords on to the pulleys after winding up the blinds. The winding-roller of each
blind is provided with a suitable catch or click to hold the blind against the stress
of its driving spring.
"
The blinds are released separately at any desired interval of time either by
means of an oscillating lever or pallet, operated by a cord, push, pneumatic
or other suitable device, or one blind may be arranged to release the other after a
certain interval. The release of the blinds may be effected by a separate "time
device, which may consist of a cam or lifter operated by a spring or spring-driven
train of clock-work. The speed of movement of the lifter controls the interval of
time between the release of each blind; this speed may be altered by adjusting the
tension of the spring, or by means of a brake. Or instead two lifters or cams may
be used which can be adjusted to release the blinds at different times. The lifters
or time device can also be provided with detents to stop same in their movement
and so keep the shutter open; or for stopping and starting same at will after being
set to operate in a limited period of time. In addition to the herein before described
means for controlling the time of exposure by the two blinds the tension of the
driving spring of each blind may be adjusted for the same purpose.
A shutter of
the form last herein before described is particularly suited to operate immediately
in front of the sensitive surface, but may also be used in any other desired
position.
The complete shutter mechanism may be arranged to travel with the lens or
optical system, or remain in a fixed position within the camera according to which
modification of the shutter is adopted.
The frame or carrier for the sensitive surface may be constructed to revolve, so
as to readily change the longest side of the picture to either vertical or horizontal,
as required, and may at the same time shift à mask on the finder screen, so that the
picture visible thereon may be of identical shape and position.
Dated this 10th day of Jul 1900

page_text: COMPLETE SPECIFICATION.
Improvements in Photographic Cameras and Parts thereof.
I, JOHN EDWARD THORNTON of 3 New Lorne Street, Moss Side, Manchester,
in the County of Lancaster, Manufacturer, 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:-
This invention relates to what are known as hand or detective photographic
cameras and to shutters applicable to both hand and field cameras and is designed
with the object of providing a compact, portable, and light hand camera and a
"self-capping" blind shutter, that is, one that does not require the sensitive surface
to be covered whilst being set as the setting is performed without moving the
blind or exposing the sensitive plate to light.
It consists essentially of (a) the general arrangement of the several parts of the
camera and (b) of a shutter composed of an endless flexible blind passing over two
or more rollers with suitable apertures for the light to pass through.
The invention will be fully described with reference to the accompanying
drawings.
Fig. 1, sectional elevation of camera with the parts arranged according to my
improvements.
Fig. 14, sectional elevation of same showing revolving back applied thereto.
Fig. 2, front elevation of same partly in section.
Fig. front elevation in section of my improved shutter.
Fig. 4, end elevation of same.
Fig. 5, vertical sectional elevation of same.
Referring to Figs. 1-2 I construct the camera of a rectangular box or case A
of ordinary construction at one end of which is placed the optical system and at
the other the sensitive plates or surfaces.
The magazine B, which holds the sensitive plates, is placed in the back end of
the camera which opens so that the magazine can be inserted or withdrawn with-
out disturbing or disarranging any other part of the instrument, the plates being
changed in the ordinary way. Instead of a magazine to hold plates as shown a
sensitive film wound from one roller to another may be substituted and placed to
occupy the position of the magazine B.
Where an oblong plate is used I make the back portion of the case to which
the magazine is attached, and which I term the carrier, revolve, without admitting
light to the interior, to give pictures either the horizontal or vertical way of the
plate without need of turning the camera on its side as shown in Fig. 14.
At the other end of the case A is placed an inner sliding case C which carries
the lens D. The sliding case C is moved in and out by a rack E and pinion E¹
operated by the knob e and the position of the lens is adjusted thereby.
The lens I prefer to use is one of the "doublet" or rapid rectilinear class of
short focus say from 4 to 5 in. for plate pictures with a large working aperture.
The glass d forming the back combination of the lens is mounted rigidly in the
tube d. The front combinations of the lens are mounted in a moving or sliding
plate F which carries two or more glasses either of which can be slid in front of the
glass d and into the path of light passing there through. Between the two glasses
I place a diaphragm such as is known as the "Iris" or other form or simply a
sliding plate G with two three or more holes of different diameter made therein.
The relative position of the diaphragm to the lens or the ratio between the size of
the aperture in the diaphragm G to the focus of the lens is indicated by the
pointers 9 on a scale on the top of the flange H visible from outside the camera
through the aperture. The flange H noves to and fro with the front glasses.
The finder which I use both for obtaining a correct and sharp focus and for
finding the principal object and composing the picture, I place in front of the

page_text: magazine carrying the sensitive plates. This finder consists of a mirror I set at an
angle of 45°, and a screen of ground glass or celluloid J in one side of the case A
upon which the picture is projected by the same lens as that used to take the
photograph.
The mirror I is pivoted upon a centre about which it is rotated by a spring so
that when released at the lower end it can assume a horizontal position and cover
the screen J to prevent admission of light. When the correct focus is ascertained
and the desired picture obtained, the mirror I is released by drawing back the
spring catch when the spring causes it to rise and cover the screen J.
To reduce the weight of the mirror I, instead of using silvered glass I may use a
transparent silvered celluloid, mica, or other suitable light material mounted in a
frame and pivoted at one end. Or if a flexible mirror can be obtained from the
above materials the mirror when released may be rolled up upon a roller.
I place a spring blind shutter K between the mirror I and the lens D in such a
position that the upward movement of the mirror releases the spring catch k which
holds the shutter K. The shutter K may be of the ordinary spring blind type
of instantaneous shutter but I prefer to use my improved shutter such as herein-
after described with reference to Figs. 3-5.
Referring to Figs. 3, 4, and 5 I construct my improved shutter of an endless
blind L passing round a top roller M and a bottom roller N. In the blind are cut
two apertures through which the exposure of the sensitive plates to the light is
effected. When the camera is at rest and the shutter closed, the apertures will
be, one over the top roller and the other beneath the bottom roller. On the
release of the blind as it moves forward the apertures change place and as they
pass the exposure is made. The blind is then in position for another exposure
without re-setting, the driving mechanism only requiring to be wound up. One
roller, preferably the top roller, M, is driven by means of a coiled or volute spring O
one end of which is attached to a loose sleeve o on the spindle of the roller. On
the inner end of the sleeve is a clutch disc P which engages with a similar clutch
disc P' on the end of the top roller M. A sheave or pulley R is attached to the
sleeve o upon which the cord r is wound up. The spring O also acts to keep the
clutch discs in contact. The other end of the spring O is attached to a movable
cover S with ratchet teeth on its periphery gearing with a spring pawls by which
the tension of the spring O can be adjusted to regulate the speed of travel of the
blind shutter. On the outer end of the roller spindle is placed a small nut m to
keep the cover S in position and a small spring catch or pawl p engages with a
notch cut in the periphery of the disc P¹ attached to the roller M to prevent the
roller turning backwards when the spring is being wound up and to adjust the
position of the blind after each exposure. The roller M may be roughened or
made with small spikes or pins projecting therefrom to grip the blind or if found
necessary a second roller may be placed against it to revolve in frictional contact
with it.
The shutter may be arranged as shown in Figs. 3-5 to fit onto the lens hood or
as shown in Figs. 1 and 2 in the interior of the camera instead of passing the blind
only over two rollers the endless blind may be passed over three four or more
rollers so as to pass round in front of and behind the lens or in front of and
behind the sensitive surface or, in front of the sensitive surface and then behind the
lens in which case several apertures may be cut in the blind at intervals according
to the length of the blind to correspond with the distance of travel.
The blind is released and the travel of the blind regulated by any well known
form of releasing mechanism now applied to what are known as instantaneous
shutters such for example the mechanism shown and described in the Specification
of my former Patent No. 12238 of 1886 which may as desired be adjusted to give
either an instantaneous or a time exposure.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I wish it to be understood

page_text: that with the exception of the continuous blind shutter I make no claim for any
single part of the camera taken separately but I declare that what I claim is :-
1. A photographic hand camera having the several parts constructed and
arranged in a compact form substantially as described and shown with reference to
Figs. 1 to 2.
2. A shutter for photographic cameras having an endless blind substantially as
and for the purposes described.
3. A shutter for photographic cameras having an endless rotary blind passing
over two or more rollers, a spring attached to a loose sleeve and connected to the
driving roller by a clutch to move the roller in one direction and mechanism to
release and control the travel of the blind substantially as described and shown
with reference to Figs. 3, 4, and 5.
Dated this 18th day of April 1891.
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.