Improvements in Apparatus for Produoing and Exhibiting Colour Photographs, and for the Production of Photo-mechanical Printing Blocks.
Year: 1896

page_text: Date of Application, 24th Apr., 1898
Complete Specification Left, 22nd Jan., 1897-Accepted, 13th Mar., 1897
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Produoing and Exhibiting Colour
Photographs, and for the Production of Photo-mechanical
Printing Blocks.
:
1, WALTER WHITE, of 70 Shirland Road, Paddington, in the County of
Middlesex, Photo-engraver do hereby declare the nature of this invention to be.as
follows:-
My invention relates to improvements in apparatus for producing and viewing
colour photographs or photographic colour-records.
In what is known as three-colour photographic work it is usual to make a series
of three negatives either by separate exposures in an ordinary camera, or by simul-
taneous exposures with one objective in a special camera, each negative being
produced by light rays of a certain colour acting through a coloured screen or
light-filter upon a suitably sensitised plate. Such a series of negatives constitutes
a complete colour-record of the object photographed, and transparencies made from
such a series and viewed by superposition of the light passing through them and
through appropriate coloured screens show the natural colours of the original. Or.
such a series of three negatives may be used for three-colour printing by photo-
graphic or photo-mechanical processes.
By Diy invention I facilitate the production and viewing of such colour photo-
graphs, and 1 produce improved results by simpler and more convenient means than
have hitherto been used.
To produce the three negatives representing the red, green and blue-violet colour
sensations I construct and employ a special camera. This camera is fitted with a
lens or objective as for ordinary pliotography, and is constructed to carry three
sensitive plates one of which is placed opposite to the lens, in the focal plane; the
other two plates are placed each at a right angle to the focal plane, parallel to each
other, but on opposite sides of the camera. In the camera two transparent or semi-
transparent mirrors are used as reflectors and transmitters of light each at an angle
of 45 degrees to the focal plane but at an angle of 90 degrees to each other. The
firat mirror or that immediately behind the lens reflects portion of the light
passing through the lens and forms an image upon a sensitive plate on one side of
the camera. The remainder of the light passes through this mirror and a further
portion of it is reflected by the second mirror which is at an angle of 90 degrees to
the first and forms an image upon a sensitive plate on the opposite side of the
camera. The residue of the light passes through this second mirror and forms
an image upon a third sensitive plate placed at the back or end of the camera
as in ordinary photography. The correct focussing of the images is performed
by the backward or forward movement of the lens by means of rackwork or screw
or other suitable motion; the plates being placed at such distances from the mirrors
8 ensure the images being in correct focus at the same time upon the surfaces of
he three sensitive plates.
The mirrors used are plane transparent or semi-transparent mirrors, and may be
f plain or coloured glass, or glass covered with a coloured coating, or glass thinly
latinized or silvered.
J
J
:

page_text: The colouring of each of the mirrors may be complementary to the colour of
the light that acts upon its respective plate. The first mirror or that immediately
behind the lens may be of yellow glass or glass prepared with a yellow coating,
the plate used being in this instance sensitive principally to blue or violet. Such
blue rays as pass into the glass will then be absorbed and not reflected from the
rear surface, and therefore no double image will be produced on the sensitive
surface. For the second mirror I may employ an orange or red glass, or glass
prepared with an orange or red coating. Any secondary image that may he
reflected from the rear surface of this mirror will contain no green rays to which
the second plate is sensitive. The third plate at the back or end of camera specially
sensitive to the red and yellow rays will in such case receive only the red and yellow
rays that are allowed to pass through the two mirrors.
In addition to the two mirrors, colour screens or light filters may be used in front
of the sensitive plates according to the sensitiveness or colour-sensitiveness of the
plates. If silvered or platinized mirrors are used they may consist of thinly
silvered or platinized plain or coloured glass or glass covered with a coloured coating
on one surface and they may be used either with or without additional colour screens.
In any case the colours of the mirrors and screens must be such as together
with the special preparation of the plates will allow only the light representing one
of the three colour sensations to act upon each plate, and to produce properly timed
or exposed results upon the three plates with a single oxposure; the three plates
when developed being negatives each of which represents one of the three funda-
mental colour sensations. If negatives are required representing modifications or
combinations of the fundamental colour sensations they may be obtained by altering
the colours of the mirrors or screens or the preparation of the sensitive plates, or by
a combination of such alterations.
With some lenses the foci of the different coloured light rays are not identical;
so that to produce in the three required negatives images of equal sharpness the
plates must be at unequal distances from the lens. These unequal distances may
be secured by moving one or more of the plates backwards or forwards parallel
to its original position. I improve upon this method by employing in my camera
or apparatus a support or stand for each of the mirrors, each support or stand
being moveable by rackwork screw or other suitable motion backwards or forwards,
from or towards the lens, parallel to its original position, and carrying the mirror
at the same angle in relation to the other mirror and the focal plaue. By this
means each of the mirrors can be moved independently of the other towards or
from the lens, thus shortening or lengthening the distance from the leus to the
surface of the mirror and consequently from the lens to the plate upon which
this reflects an image. In conjunction with this the seusitive plates at the sides of
the camera or the frames or slides carrying these plates may be made moveable
sideways in the same plane towards the front or back of the camera; this renders
it possible to make the exact centres of the plates correspond.
For utilising the camera as a viewing instrument I remove the lens and may
replace this by a magnifying eyepiece, and 1 employ two or more reflectors. Or
1. may use an apparatus similar in construction to such camera, but without a
photographic lens or objective, or with a magnifying eyepiece. From the three
negatives obtained by the camera as before described I make three transparencies
or positivo pictures on glass or other transparent material, and placing them, not
inverted, in the camera or viewing apparatus in similar positions to those previously
occupied by the sensitive platos I am enabled to view them through the front
aperture or eyepiece by transmitted and reflected light aud by using coloured
screens or by colouring the transparencies so that the light passing through the
transparencies is in each case similar to the light of that colour sousation which
the transparency represents 1 obtain by thus viewing them a combination or super-
position of the three transparencies of the colour sensations each in its own colour
and consequently an image in the natural colours of the original.
In using the camera for producing upright photographs, that is photographs

page_text: whose height is greater than their width I employ it in the manner described
that is with the mirrors perpendicular to the horizontal plane, and reflecting two
images to the opposite sides of the camera; and viewing the resulting transparencies
I employ the camera or apparatus in the same way with the addition of reflectors
outside and at each side of the apparatus, the whole being pointed towards a bright
sky, or downwards towards a third reflector. It is obvious that by turning the
camera or apparatus on one side horizontal photographs may he produced and
viewed; in this case one of the plates or transparencies will be at the top and one
at the bottom of the camera or apparatus. The same arrangement of reflectors for
viewing may be used, but if the apparatus is pointed downwards the side reflector
that now becomes the top reflector may be dispensed with and direct light from the
sky utilised.
Stereoscopic negatives may be produced in the same way as single negatives by
using two lenses and plates of suitable size, and the resulting stereoscopic
transparencies may be viewed in a similar camera or apparatus fitted with a
stereoscopic eyepiece.
The three transparencies may be employed in conjunction with colour screens
for projection by a triple optical lantern, or with a single source of light a special
lantern may be used containing in addition to the usual front condenser two
condensers on opposite sides of the source of light each having a mirror to reflect
the light at a right angle. Thus by affixing my camera or apparatus as for
viewing, together with a suitable lens for projection purposes, the light passes
directly through the central transparency and by reflection through the two side
transparencies. Instead of affixing a camera or viewing apparatus to an optical
lantern of such construction I may employ a lantern, specially constructed as
described for one source of light, the front portion being of such construction ns
to be similar to my camera or apparatus in its arrangement of transparencies
mirrors and reflectors.
Coloured lantern slides for ordinary single optical lantern projection may be
made by printing in transparent colours such as gelatine dyed either before or after
printing or developing, and superimposing these prints in correct register; the
negatives representing the green, red and blue-violet sensations should for this
purpose be printed from respectively in pink, eyan-blue and yellow.
Similarly this principle of colour-printing may be applied to the production of
printing-blocks made from the three negatives, or they may be made to furnish
plates for collotype printing, intaglio plates for photogravure printing, or moulds
for Woodburytype printing, the three impressions giving in ench case, when
superposed, the required tints to accurately reproduce the colours of the original.
Dated this 23rd day of April 1846
WALTER WHITE.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Producing and Exhibiting Colour
Photographs, and for the Production of Photo-mechanical
Printing Blocks.
I, WALTER WHITE, of 70 Shirland Road, Paddington, in the County of
Middlesex, Photo-engraver, do bereby 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 improvements in apparatus for producing and viewing
colour photographs or photographic colour-records.
In what is known as three-colour photographic work it is usual to make a series

page_text: by
of three negatives either by separate exposures in an ordinary camera or
simultaneous exposures with one objective in a special camera, each negative being.
produced by light rays of a certain colour acting through a coloured screen or
light-filter upon a suitably sensitised plate. Such a serios of negatives constitutes
a complete colour-record of the object photographed, and transparencies made
from such a series and viewed by superposition of the light passing through them
and through appropriate coloured screens show the natural colours of the original.
Or such a series of three negatives may be used for three-colour printing by
photographic or photo-mechanical processes.
By my invention I facilitate the production and viewing of such colour photo-
graphs, and I produce improved results by simpler and more convenient means
than have hitherto been used.
To produce the three negatives representing the red, green and blue-violet
sensations construct and employ a special camera.
In the accompanying drawings:-
Figure 1 is a sectional plan of a camera or apparatus for producing negatives in
accordance with my invention.
Figure 2 is a perspective view of the same with lid raised to show the construction,
and indicating the position of the reflectors required to convert the same into a
viewing instrument.
Figure 3 is a plan of a moveable mirror-stand.
Figure 4 is a sectional elevation of my camera or apparatus in use as a viewing
instrument for horizontal pictures.
Figure 5 is a sectional plan of the same arranged as an optical lantern for
projecting coloured pictures on a screen.
For the production of negatives my camera is fitted with a lens or objective A
as for ordinary photography, and consists of a casing or box B constructed to carry
three sensitive plates one of which is placed at. C opposite to the lens, in the focal
plane; the other two plates are placed at D and E each at a right angle to the
focal plane, parallel to each other, but on opposite sides of the camera. In the
camera two transparent or semi-transparent mirrors F and G are used as reflectors
and transmitters of light each at an angle of 45 degrees to the focal plane but at
an angle of 90 degrees to each other. The first mirror F or that immediately
behind the lens reflects a portion of the light passing through the lens and forms
an image upon a sensitive plate at D on one side of the cainera. The remainder
of the light passes through this mirror F and a further portion of it is reflected
by the second mirror G which is at an angle of 90 degrees to the first and forms
an image upon a sensitive plate at E on the opposite side of the camera. The
residue of the light, which passes through this second mirror G, forms an image
upon a third sensitive plate placed at C at the back or end of the camera as in
ordinary photography. The correct focussing of the images is performed by the
backward or forward movement of the lens A by means of rackwork or screw or
other suitable notion, the plates being placed at such distances from the mirrors
as ensure the images being in correct focus at the same time upon the surfaces of
the three sensitive plates. A lens working at a fixed focus inay be employed,
either with or without supplementary lenses for objects at different distances.
The mirrors F and G are plane transparent or semi-transparent mirrors, and
may be of plain or coloured glass, or glass covered with a coloured coating, or glass
thinly platinized or silvered."
The colouring of each of the mirrors may be complementary to the colour of the
light that acts upon its respective plate. The first mirror For that immediately
behind the lens may be of yellow glass or glass prepared with a yellow coating, the
plate used at D being in this instance sensitive principally to blue or violet. Such
blue rays as pass into the glass F will then be absorbed and not reflected from the
rear surface, and therefore no double image will be produced on the sensitive
surface at D. For the second mirror G 1 may employ an orange or red glass, or
glass prepared with an orange or red coating. Any secondary image that may

page_text: be reflected from the rear surface of this mirror will contain no green rays to
which the second plate at E is sensitive. The third plate at C at the back or and
of camera specially sensitive to the red and yellow rays will in such case receive
only the red and yellow rays that are allowed to pass through the two mirrors F
and G.
In addition to the two mirrors F and G colour screens or light-filters may be
used in front of the sensitive plates according to the sensitiveness or colour-
sensitiveness of the plates. A colour screen may be used behind or in front of the
lens.
If silvered or platinized mirrors are used they may consist of thinly silvered or
platinized plain or coloured glass or glass covered with a coloured coating on one
surface and they may be used either with or without additional colour screens. In
any case the colours of the mirrors and screens must be such as together with the
special preparation of the plates will allow only the light representing one of the
three colour sensations to act upon each plate, and to produco properly timed or
exposed results upon the three plates with a single exposure; the three plates
when developed being negatives each of which represents one of the three
fundamental colour sensations. If negatives are required representing modifi-
cations or combinations of the fundamental colour sensations they may be obtained
by altering the colours of the mirrors or screens or the preparation of the sensitive
plates, or by a combination of such alterations.
An opaque screen or division should be placed in the camera between C and D
to prevent stray light from acting upon the plates.
To cut off any direct light that might act upon the seusitive plate at E I employ
an opaque and uon-reflecting flap or screen H hinged to the side of the camera and
adjusted by a screw J passing through to the outside of the camera. The flap or
screen is held against and made to follow the movement of the screw J by a small
spring K.
With some lenses the foci of the different coloured light rays are not identical;
so that to produce in the three required negatives images of equal sharpness the
sensitive plates must be at unequal distances from the lens. These unequal
distances may be secured by moving one or more of the plates backwards or
forwards parallel to its original position. I improve upon this method by
employing in my camera or apparatus a support or stand for each of the mirrors,
each support or stand being moveable by rackwork sorew or other suitable motion
backwards or forwards, from or towards the lens, parallel to its original position,
and carrying the mirror at the same angle in relation to the other mirror und the
focal plane. Figure 3 is the plan of a moveable mirror stand adjustable by hand
and fixed in position by two screws. By this means each of the mirrors cau be
moved independently of the other towards or from the lens, thus shortening or
lengthening the distance from the lens to the surface of the mirror and con-
sequently from the lens to the plate upon which this reflects an image.
conjunction with this the sensitive plates at the sides of the camera or the frames
or slides carrying these plates may be mado moveable sideways in the same plane
towards the front or back of the camera; this renders it possible to make the
exact centres of the plates correspond.
Io
For utilising the camera as a viewing instrument I remove the lens and
may replace this by a magnifying eyepiece M, and I employ two or more
reffectors N, O, P. Or 1 may use an apparatus similar in construction to such
camera, but without a photographic lens or objective, or with a magnifying
eyepiece. From the negatives obtained by the camera as before described I make
three transparencies or positive pictures on glass or other transparent material,
and placing them, not inverted, in the camera or viewing apparatus in similar
positions to those previously occupied by the seusitive plates at C, D and E 1 am
enabled to view them through the front aperture or eyepiece by transmitted and
reflected light and by using coloured screens or by colouring the transparencies
so that the light passing through the transparencies is in each case similar to the

page_text: light of that colour sensation which the transparency represents 1 obtain by thus
viewing them a combination of the three transparencies of the colour sonsations
each in its own colour and consequently an image in the natural colours of the
-original.
In using the camera for producing upright photographs, that is photographs
whose height is greater than their width, I employ it in the manner described that is
with the mirrors F, G perpendicular to the horizontal plane, and reflecting two
images to opposite sides of the camera, and viewing the resulting transparencies I
employ the camera or apparatus in the same way with the addition of reflectors N, O
outside and at each side of the apparatus, the whole being pointed towards a bright
sky or downwards towards a third reflector. It is obvious that by turning the
camera or apparatus on one side horizontal photographs may be produced and
viewed in this case one of the plates or transparencies will be at the top and one
at the bottom of the camera or apparatus. The same arrangement of reflectors
for viewing may be used, but if the apparatus is pointed downwards as in Figure 4
the side reflector that now becomes the top reflector may be dispensed with and
direct light from the sky utilised.
The apparatus when used as a viewing instrument may, instead of being pointed
downwards towards a third reflector, be pointed upwards towards the sky or other
suitable source of light, and a third reflector of small size attached to the outside
of the front end of the apparatus at an angle of 45 degrees reflecting the image
upwards to the eye offers a convenient means of viewing. In this case the
transparencies must be inverted when placed in position.
Stereoscopic negatives may be produced in the same way as single negatives by
using two lenses and plates of suitable size, the camera being used in the same
position as in taking a horizontal view, and the resulting stereoscopic trans-
parencies may be viewed in a similar camera or apparatus fitted with a stereoscopic
eyepiece.
The three transparencies may be employed in conjunction with colour screens for
projection by a triple optical lantern or with a single source of light as in Figure 5
a special lantern inay he used containing in addition to the usual front condenser R
two condensers S, T on opposite sides of the source of light each having a
mirror V, X to reflect the light at a right angle. Then by affixing my camera or
apparatus as for viewing, together with a suitable lens Y for projection purposes
the light passes directly through the central transparency and by reflection
through the two side transparencies. Instead of affixing a camera or viewing
apparatus to an optical lantern of such construction I may employ a lantern,
specially constructed as described for one source of light, the front portion being
of such construction as to be similar to ny camera or apparatus in its arrangement
of transparencies mirrore and reflectors.
Coloured lantern slides for ordinary single optical lantern projection may be
made by printing in transparent colours such as gelatine dyed either before or after
printing or developing, and superimposing these prints in correct registor; the
negatives representing the green, red, and blue-violet sensations should for this
purpose be printed from respectively in pink, cyan-blue, and yellow.
Similarly this principle of colour printing may be applied to the production of
printing-blocks made from the three negatives, or they may be inade to furnish
plates for collotype printing, intaglio plates for photo-gravure printing, or moulds
for Woodburytype printing, the three impressions giving in each case when
superimposed the required tints to accurately roproduce the colours of the
original.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, 1 declare that what
I claim is
1. A camera or apparatus for producing viewing or exhibiting colour
photographs, consisting of a casing constructed to carry three sensitive plates or

page_text: transparencies and containing two transparent mirrors at an angle of 90 degrees to.
each other so disposed as to reflect images upon two sensitive plates or from two.
transparencies on opposite sides which may be the upper and lower sides of such
camera or apparatus, each mirror being at an angle of 45 degrees to the focal plane
or third plate or transparency substantially as herein before specified.
2. A stereoscopic camera or apparatus for producing viewing or exhibiting
colour photographs, containing two transparent mirrors at an angle of 90 degrees
to each other so disposed as to reflect images upon two sensitive plates or from two
transparencies at the upper and lower sides of such camera or apparatus
substantially as herein before specified.
3. An exhibiting apparatus for projection purposes having three condensers on,
three sides of a single source of light with a reflector to each of the two opposite.
side condensers for use with or attached to a viewing or exhibiting apparatus of
such description as described in the preceding firet claiming clause substantially as.
hereinbefore specified.
4. In a camera or apparatus for producing viewing or exhibiting colour photo-
graphs two transparent mirrors at an angle of 90 degrees to each other so disposed
as to reflect images upon two sensitive plates or from two transparencies on opposite
sides which may be the upper and lower sides of such camera or apparatus, each
mirror being at an angle of 45 degrees to the focal plane or third plate or
transparency substantially as hereinbefore specified.
Dated this 20th day of January 1897.
WALTER WHITE,
70, Shirland Road, Paddington, W., Applicant.