Improvements in Colour Photography.
Year: 1899

page_text: Improvements in Colour Photography.
I, 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 improvements in taking photographs in natural
colours by what is known as the three colour process, whereby I am enabled to
take such photographs with greater efficiency and to photograph moving objects
as well as still life.
use
According to my invention, instead of employing (as has hitherto generally
been the case) either a number of separate cameras placed side by side or a single
camera in which a number of sensitive plates are successively exposed,
a single camera having the necessary number of lenses all of the same focus and
provided with means whereby the said lenses may be simultaneously exposed.
Each lens is provided with a different colour filtering screen and the camera is
divided into a number of compartments corresponding respectively with the
lenses and so arranged that the plate when in position is divided into a corre-
sponding number of equal parts. Thus ensuring that a number of identical
negatives will be obtained at one exposure, from which a true rendering of the
original in colours may be obtained."
According to one form of construction embodying my invention, employ a
camera having a bellows body and the usual movements and provided with
either double backs of ordinary book form to take two plates or films each, or a
changing back to hold a number of glass plates or films. To the front of this
camera I attach three lenses side by side either horizontally or vertically and
provide them with a flap or other shutter whereby they may be simultaneously
exposed. The interior of the camera is divided into three equal parts or chambers
(one for each lens), preferably by means of two strips of flexible material mounted
on spring rollers so as to work with the bellows part of the camera. These flexible
strips have their ends at one extremity situated at the front of the camera and
their ends at the opposite extremity situated near the focusing screen, in such
manner as to divide the plate into three equal parts.
The lenses are each supplied with a different colour filtering screen in order
to obtain negatives (in monochrome) of the relative values of the colours filtered
by the aid of the said lenses and screens. These lenses may either be rectilinear
or single landscape lenses, but for advanced work and badly lit subjects I prefer
the rectilinear.
The colour filtering screens-light red, blue violet, and green or yellow,
respectively are preferably of optically ground glass but may be of dyed cellu-
loid 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 vellow screen a medium stop.

page_text: 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 the exposure is made therefore, (provided the lenses are properly paired
and the colour screens in correct position), there will be three distinct images
each identical to the other and each having its correct proportion of colour.
Dated this 17th day of Kohruary 1899
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements in Colour Photography.
I, 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, and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to improvements in taking photographs in natural
colours by what is known as the three colour process, whereby I am enabled to
take such photographs with greater efficiency and to photograph moving objects
as well as still life.
According to my invention, instead of employing (as has hitherto generally
been the case) either a number of separate cameras placed side by side or a single
camera in which a number of sensitive plates are successfully exposed, I use
a single camera having the necessary number of lenses all of the same focus and
provided with means whereby the said lenses may be simultaneously exposed.
Each lens is provided with a different colour filtering screen and the camera is
divided into a number of compartments corresponding respectively with the
Jenses and so arranged that the plate when in position is divided into a corre-
sponding number of equal parts. Thus ensuring that a number of identical
negatives will be obtained at one exposure, from which a true rendering of the
original in colours may be obtained.
According to one form of construction embodying my invention, I employ a
camera having a bellows body and the usual movements and provided with
either double backs of ordinary book form to take two plates of films cach, or a
clanging back to hold a number of glass plates of films. To the front of this
camera I attach three lenses side by side either horizontally or vertically and
provide them with a flap or other shutter whereby they may be simultaneously
exposed. The interior of the camera is divided into three equal parts or chambers
(one for each lens), preferably by means of two strips of flexible material mounted
on spring rollers so as to work with the bellows part of the camera. These flexible
strips have their ends at one extremity situated at the front of the camera and
their ends at the opposite extremity situated near the focussing screen, in such
manner as to divide the plate into three equal parts.
The lenses are each supplied with a different colour filtering screen in order
to obtain negatives (in monochrome), of the relative values of the colours filtered
by the aid of the said lenses and screens. These lenses may either be rectilinear

page_text: or single landscape lenses, but for advanced work and badly lit subjects I prefer
the rectilinear.
The colour filtering screens-light red, blue violet, and green or yellow,
respectively are preferably of optically ground glass but may be of dyed cellu-
loid 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
shp 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 the exposure is made therefore, (provided the lenses are properly paired
and the colour screens in correct position,) there will be three distinct images
cach identical to the other and each having its correct proportion of colour.
And 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 of a camera constructed according to this invention.
Fig. 2 is a horizontal section on the line A B Fig. 1, and
Fig. 3 is a vertical cross section on the line C D Fig. 2.
The camera is constructed with a front plate A having the three lenses 13 B1 B2
all of the same focus. These lenses are each provided with the colour
screens arranged behind the lenses the colour screens being of the
requisite colours to give the three photographs in the proper colours required, for
three colour photography. The camera is completed by means of the bellows
body and the movable back plate 1) adapted to receive the dark slide holding
the photographic plate and being provided with a hinged ground glass screen E
which can be turned up out of the way when the dark slide is in place. For the
purpose of dividing the camera into three compartments flexible partitions F
are provided having a certain amount of springyness so that when released they
will collapse and allow of the colour screens being got at easily. These
partitions are provided with rigid bars f each fitted at their ends into slots
upon the back plate D. These partitions F being of a flexible character will
therefore extend or collapse in accordance with the movements of the bellows
body C. The front A of the camera is attached to the base board G and the
focussing is effected by the movement of the back 1) which is operated by pinions
engaging in the racks upon the base board G the milled head serving for
rotating the pinions. In order to effect slight adjustments of the lenses B B¹ B³
they are mounted on a sliding frame A fitting in grooves in the front A of the
camera and the longitudinal slot a in which a milled screw a¹ engages allows of a
slight vertical adjustment.
Shutters III are fitted to the lenses B B1 B2 and are connected together by
means of a rod i operated by a milled head so that all three lenses can be
exposed simultaneously.
The lenses are provided with differently sized apertures and with stops in order
to allow for the differences required for the particular colour screen in use in
each lens.
It will be seen that a single camera is thus obtained in which the three photo-
graphs in monochrome required for three colour photography can be obtained
at one exposure the focussing for all three and the exposure being effected
simultaneously.
The three photographs are obtained upon one plate and as a result the three
photographs will be obtained side by side identical with one another but each
having its proper proportion of colour.

page_text: Any desired construction of dark slide may be used and instead of the shutter
mechanism shown any other convenient arrangement may he used provided that
all three shutters can be used simultaneously.
The colour screens may be
variously arranged in position relatively to the lenses or if found more con-
venient may be placed adjacent to or in contact with the sensitive plate.
my said
Having now particularly described and ascertained the nature of
invention and in what manner the same is to be performed, I declare that what
I claim is:—
(1). In a camera for three colour photography, a camera body provided with
three lenses fitted with the proper colour screens, a movable back whereby the
focussing of all three negatives is simultaneously effected, a sensitive plate adapted
to have the three negatives upon it side by side and a shutter mechanism whereby
an exposure can be obtained for all three lenses simultaneously, substantially as
described.
(2). In a camera for three colour photography, a camera front having three
lenses side by side each fitted with the proper colour screen, a bellows body, a
back frame adapted to receive a sensitive plate upon which all three negatives
will be obtained side by side, flexible partitions dividing the interior of the
camera into three divisions, rack and pinion gear for effecting the movements of
the back frame for simultaneous focussing, and shutter mechanism whereby an
exposure can be obtained for all three lenses simultaneously substantially as
described.
(3). In a camera for three colour photography, a front plate A, lenses B B B²,
colour screens behind them, bellows body C, movable back plate 1
adapted to receive the dark slide and provided with a ground glass screen G,
flexible partitions F, rack and pinion gear for focussing by means of the move-
ments of the back plate D, and shutters I I' I adapted to be operated together
substantially as described with reference to the drawings and for the purposes
specified.
Dated this 17th day of November 1899.
GEO. H. RAYNER,
37, Chancery Lane, London, Agent for the Applicant.