Improvements in Colour Photography.
Year: 1899

page_text: Improvements in Colour Photography.
1, WILLIAM NORMAN LASCELLES DAVIDSON, of 3, White Rock Road, Southwick,
near Brighton, in the County of Sussex, Captain 4th Battalion The Kings
(Liverpool Regiment), do hereby declare the nature of this invention to be as
follows:-
This invention relates to means for taking photographs in natural colours
by what is known as the three colour process and consists. essentially in the
construction and mechanism of the camera employed whereby greater efficiency
is obtained.
According to the first arrangement, a triple camera is employed having
three lenses and divided into three compartments by partitions between the
lenses so that three similar negatives can be obtained on the same plate or on
three separate plates behind each lens.
The lenses are each supplied with a different colour filtering screen in order
to obtain negatives of the relative values of the colours filtering by the aid
of the lenses and screens. These lenses may either be rectilinear or single
landscape lenses but for advanced work and badly lit subjects rectilinear lenses
are preferably employed.
The colour filtering screens-light red, blue-violet, and green or yellow,
respectively are preferably of optical ground glass but may be of dyed celluloid
or other transparent material.
Each lens has a different sized aperture, the lens with the red screen having
the largest, that with the blue-violet screen the smallest, and that with the
green or yellow screen a medium stop.
The colour screens may be fitted to their respective lenses by being slipped
into suitable holders at the backs of the lenses. Or coloured stops may be made
to slip into the lenses-between the combinations in the case of rectilinear
lenses, or in front or behind in the case of a single lens.
Or a coloured screen may be used in conjunction with the sensitive plate and
either in contact with it or not. Or in place of said screens, the glasses of which
the lenses are composed, may be dyed to the necessary colours.
When using this camera for copying paintings, and like work it is sufficient
to expose all three lenses at once so that three distinct images are obtained
having each its correct proportion of colour. When not copying paintings, etc.,
and for general work the three images thus obtained would not be exactly
identical and it is therefore necessary to provide some means whereby all three
exposures shall be made at exactly the same position. The second portion of
this invention consists in mechanism for effecting this.
The triple camera as above described is fitted upon a baseboard capable of
sliding in grooves in the top of the stand. A rubber or other spring device is
attached to the baseboard so that its tendency is to cause the baseboard and
therefore also the camera to move the correct distance after each exposure.

page_text: At suitable positions on the baseboard catches are provided which press
against rods upon the edge of the baseboard so that the camera is prevented from
moving under the, influence of the above mentioned, spring until the exposure
has been made.
"
These rods are mounted on a spindle extending lengthwise of the stand and
by vibrating this spindle through an angle sufficient to pass one of the rods over
its catch, the spring will then slide the camera until again stopped by the next
catch.
Another operation will serve to move the camera to a third position.
By this mechanism it will be seen that the camera takes up three distinct
positions the proper lens being uncovered at each position, so that three expo-
sures are obtained all from the same actual position' each lens being brought to
that position before exposure.
To expose the lens at the right moment drop shutters may be employed for
all three lenses. At the exposure position supports for the shutters are caused
to incline by suitable levers operated from the end of the baseboard so that the
shutters are allowed to drop at the required moment for effecting the exposure.
Instead of this, any other suitable exposure or shutter mechanism may be
employed.
The necessary movements of the camera can be very quickly effected so that
the several exposures can be taken in very quick succession and are accom-
plished by actuating one single lever at the end of the baseboard.
The camera is fitted with the usual movements and adjustments.
In a slightly modified arrangement, the plate carrier only is shifted for the
different exposures and the stops and colour screens are changed 'by suitable
mechanism, one lens only being employed.
The triple camera above described can also be used for stereoscopic work.
GEO. H. RAYNER,
37, Chancery Lane, London, Agent for the Applicant.
improvements in Colour Photography.
I, WILLIAM NORMAN LASCELLES DAVIDSON, Captain 4th Battalion The Kings.
(Liverpool Regiment), of Rose Cottage, Southview Road, Southwick, Sussex, 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 means for taking photographs' in natural colours by
what is known as the three colour process, and consists essentially in the con-
struction and mechanism of the camera employed whereby greater efficiency
is obtained.
This invention consists essentially in an arrangement whereby three photo-
graphs can be taken either at once or immediately after one another, the said
photographs having the required colour proportions for three colour photo-
graphy.
When used for paintings and such like work the three lenses can be exposed
at once, while when employed for other work the camera is shifted so that the
three lenses are all engaged from exactly the same position. The mechanism
to be hereinafter described effects the movement of the camera after each expo-
sure has been made and can be used with or without time exposure.

page_text: The lenses are each applied with a different colour filtering screen in order
to obtain negatives of the relative values of the colours filtering by the aid
of the lenses and screens. These lenses may either be rectilinear or single
landscape lenses but for advanced work and badly lit subjects rectilinear lenses
are preferably employed.
The colour filtering screens- -light red, blue-violet, and green or yellow,
respectively are preferably of optical ground glass but may be of dyed celluloid
or other transparent material.
Each lens has a different sized aperture, the lens with the red screen having
the largest, that with the blue-violet screen the smallest, and that with the
green or yellow screen a medium stop.
In order that this invention may be more clearly described reference is had
to the accompanying sheet of illustrative drawings on which
Fig. 1 is a front elevation showing a camera constructed according to this
invention and
Fig. 2 is an end view of the same partly in section.
Figs. 3 & 4 are detail views of part of the mechanism on a larger scale.
The camera A is provided with the three lens openings B B B3 and is divided
internally into three compartments by partitions between the lenses so that
three similar negatives can be obtained either on one long plate of on three
separate plates fitted one behind each lens. The lenses B B B² are provided
with the requisite colour screens as above described and by means of stops the
aperture in each case is regulated to give the required proportion according
to the colour to which each lens applies. The colour screens may be slipped
in suitable holders at the back of the lenses or they may be passed between the
combination in the case of rectilinear lenses or in front or behind of the lens
in the case of a single lens. The actual arrangement employed is not material
to this invention as the various arrangements indicated are well known.
The camera A is fitted upon a sliding carriage C attached by means of thumb
screws E or the like. The base board F is provided with standards F1 F1 at
each end supporting rods G G. Tubes CC on the sliding carriage C are
adapted to slide upon the rods G G.
Lengthwise of the base board F a rod H is arranged supported in suitable
bearings and operated by means of a rubber press ball T to cause a vibration
through a small angle. Three catches I I¹ I2 are arranged upon the underside
of the carriage C and a side rod J is. arranged upon the rod H in such position
that the camera A being moved it will be stopped at three different positions
by means of the engagement of said rod J with one or other of the catches I I¹ I²
at the positions necessary to bring each of the lenses B B B32 in turn into the
proper position for exposure. Spiral springs K attached at one end to one of
the standards F and at their other ends to the sliding carriage C cause the move-
ment of the camera along from one position to another as permitted by the
rod J as will be hereinafter described.
The lenses B B 12 are provided with the shutters bb¹ 62 having an aperture
which as it passes before each lens will give the necessary exposure. Springs
in each case serve to cause the movement of each shutter as soon as released.
The catches b 65 66 serve to release each shutter when pressed in a manner
well known. Each of the shutters is provided with a pin 7 11 12 and in
order to stop each shutter at the exposing position to allow for time exposure,
spring rods m are mounted in suitable brackets so that their ends will come
in the path of the pins 12 and will stop the shutters at the exposing posi-
tion. The lower ends of the spring rods m are provided with extensions m¹
upon which a projection -n upon the rod H can press. The rods o 01 02 are
connected to the other shutter catches + 65 66 and side projections 03 04 05 are
provided upon which another projection upon the rod H can press.
At a suitable position on the framing a sliding piece R is mounted having
a finger piece R. At its other end it is cut away slightly so that the portion R2

page_text: is at a lower level than the portion R³. A spring R serves to return it to its
proper position after each operation. A projection S on the rod H is adapted
to bear nominally on the higher portion R3, but when the sliding piece R is
moved outwardly will move through further until it bears upon the lower
portion R².
In order to describe the operation of this camera I will describe the operations
necessary for taking a photograph. The lenses B 13¹ B³ having been properly
focussed and the plates inserted the press ball T is pressed and the, rod H is
thereby vibrated through a certain angle until the rod S comes in contact with
the higher portion R³ of the sliding piece R. The projection will during
this movement press upon the side projection o³ of the rod o and will thereby
release the shutter catch of the lens B so that the shutter b is allowed to move
The neces-.
to expose the plate until stopped by the end of its spring rod m.
sary exposure being given the sliding piece R is moved and the press ball T
again pressed. The rod S can then pass on to the lower portion R2 thus per-
mitting of a further vibration of the rod H and the projection n then presses
against the side projection m³ of the spring rod so as to depress the latter to
allow of the shutter completing its movement. At the same time the pro-
jection J is disengaged from the catch I and the camera A shifts bodily until
the lens B assumes the position previously occupied by the lens B. The
operations are then similar for the lens B first for moving the shutter b¹ to the
exposure position and then completing its movement and shifting the camera
to the third exposure position.
When using the camera for copying paintings and the like it is sufficient to
expose all lenses at once so that three distinct images are obtained having each
its correct proportion of colour by operating the shutter mechanism in the
ordinary way. For other work however the three images thus obtained would
not be exactly identical and it is therefore necessary that all three exposures
be made. exactly the same position.
The necessary movement of the camera can be very quickly effected so that
the several exposures can be taken in very quick succession. If time exposure
is not required the mechanism can be simplified so that on each pressure of
the air ball the proper shutter is operated without need for any mechanism for
completing the movement as above described.
At the same time the mechanism would move the camera from one position
.to the other.
0
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
(1) In means for taking photographs according to the three colour process,
a camera having three divisions each provided with a lens having its proper
colour screen and with shutter mechanism, a sliding carriage carrying said
camera, springs tending to draw the camera towards one end of the stand, and
mechanism whereby the lenses can be exposed in turn and between each expo-
sure the camera moved so that all three exposures are made at the same position,
substantially as described.
(2) In means for taking photographs according to the three colour process,
a camera having three divisions each provided with a lens having its proper
colour screen, and with shutter mechanism, a sliding carriage carrying said
camera, a base board having guides for said carriage, springs whereby the
camera is moved from one end of the base board to the other when its move-
ment is permitted, a rod extending along said base board and provided with air
ball or other mechanism whereby it can be vibrated through a small angle, and
means whereby such vibration will cause the operation of each shutter as it is
brought to the position from which the exposure is made and whereby the

page_text: camera is moved to bring each of the lenses into position for exposure in turn,
substantially as described.
(3) In means for taking photographs according to the three colour process,
a camera having three divisions each provided with a lens having its proper
colour screen, and with shutter mechanism, a sliding carriage carrying said
camera, a base board having guides for said carriages, springs whereby the
camera is moved from one end of the base board to the other when its move-
ment is permitted, a rod extending along said base board and provided with air
ball or other mechanism whereby it can be vibrated through a small angle, a
projection upon said rod which causes the shutter of the lens which is in posi-
tion for exposure to move to the exposing position, a sliding piece whereby on
a further operation of the air ball a further vibration of the rod is permitted,
a projection which will then release the shutter thus allowing it to close again,
and a projection which is disengaged from a catch on the camera so as to permit
the camera to move under the influence of the springs to bring the next lens
into position for exposure, said projection then stopping it at that position,
substantially as described.
(4) In means for taking photographs according to the three colour process,
a camera having three divisions each provided with a lens having its proper
colour screen and with shutter mechanism, a sliding carriage carrying said
camera, a base board having guides for said carriage, springs whereby the
camera is moved from one end of the base board to the other when its movement
is permitted, a rod extending along said base board and provided with air ball
or other mechanism whereby it can be vibrated through a small angle, a pro-
jection upon said rod which causes the shutter of the lens which is in position
for exposure to move to the exposing position, a spring rod which stops each
shutter at that position to allow for time exposure, a sliding portion by which
a further vibration of the rod is permitted when the air ball is again operated,
a projection which releases the spring rod on such further vibration to permit
the shutter to close and a projection which is disengaged from a catch on the
camera so as to permit the camera to move under the influence of its springs
to bring the next lens into position for exposure, said projection stopping it
at that position, substantially as described.
Dated this 6th day of February 1900
GEO. H. RAYNER,
37, Chancery Lane, London, Agent for the Applicant.