Photography in Colours.
Year: 1895

page_text: Date of Application, 4th Sept., 1895
Complete Specification Left, 4th June, 1896-Accepted, 4th July, 1896
Photography in Colours.
I, FREDERICK WILLIAM LANCHESTER, of Cobley Hill, Alvechurch, in the
County of Warwick, Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention relates to an improved method of producing photographs in
natural colours, and has for its object to so analyse and distribute the light falling
on the sensitive plate that the said plate or a print therefrom may be afterwards
used in a suitable form of lantern or apparatus to combine and thereby reproduce
the colour or colours of the object photographed.
In one method of carrying this invention into effect I arrange a grating consisting
of a number of parallel opaque bars, between a photographic camera and the object to
be reproduced and as close to the latter as possible, the said bars being preferably
fixed at an equal distance from one another and leaving spaces between of less
width than the bars themselves. The camera is of ordinary construction and a
prism is arranged in front of or behind the lens with its axis parallel to the bars
of the grating the dispersion of the said prism being such that when the camera
is focussed on the grating the images of the slots form a series of spectra on the
focussing screen or plate.
When a combination of lenses is employed the prism may be arranged between
the lenses or one or both of the lenses may be ground in such manner as to produce
the required dispersion.
The bars of the grating should be sufficiently numerous to prevent the picture from
being unduly broken or disjointed.
isochromatic "
In taking a photograph with this apparatus I preferably use an
plate and give a rather longer exposure than ordinarily required, the resulting
negative picture contains a record of the colours of the object in the form of
shaded lines of varying intensity, a print is then taken preferably on an ordinary
lantern slide which after development is placed in a similar or identical apparatus
as that hereinbefore described and in the position originally occupied by the
photographic plate; the coloured picture is then reconstructed by exposing the
slots in the grating to a uniform source of white light, or another method may be
employed in which a lamp and condenser are placed at the back of the lantern
slide, the light issuing from the grating being thrown on a screen where the
original colours are found to be reconstituted.
The herein before described analysing apparatus may be employed to produce
pictures showing interference colours in film backed by reflecting surface as
previously used.
In landscape photography, where the grating cannot be conveniently arranged
sufficiently near the objects being photographed, a pin hole camera may be employed
or the lens may be considerably stopped down, in order that both grating and
landscape may be approximately in focus.
A screen may be employed to absorb the ultra violet rays, to prevent their
reaching the sensitized plate; a cell containing sulphate of quinine in solution may
be employed for this purpose.
DL:
100°
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birmingham, Agents for the Applicant.

page_text: Photography in Colours.
I, FREDERICK WILLIAM LANCHESTER, of Cobley Hill, Alvechurch, in the County
of Warwick, Engineer, 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 an improved method of producing photographs in
natural colours, and has for its object to so analyse and distribute the light
falling on the sensitive plate that the said plate or a print therefrom may be
afterwards used in a suitable form of lantern or apparatus to combine and
thereby reproduce the colour or colours of the object photographed.
In one method of carrying this invention into effect I arrange a grating consisting
of a number of parallel opaque bars, between a photographic camera and the object
to be reproduced and as close to the latter as possible, the said bars being
preferably fixed at an equal distance from one another and leaving spaces between
of less width than the bars themselves. The camera is of ordinary construction
and a prism is arranged in front of or behind the lens with its axis parallel to
the bars of the grating the dispersion of the said prism being such that when the
camera is focussed on the grating the images of the slots form a series of spectra
on the focussing screen or plate.
When a combination of lenses is employed the prism may be arranged between
the lenses or one or both of the lenses may be ground in such manner as to
produce the required dispersion.
The bars of the grating should be sufficiently numerous to prevent the picture
from being unduly broken or disjointed.
"
In taking a photograph with this apparatus 1 preferably use an "isochromatic
plate and give a rather longer exposure than ordinarily required, the resulting
negative picture contains a record of the colours of the object in one form of
shaded lines of varying intensity, a print is then taken preferably on an ordinary
lantern slide which after development is placed in a similar or identical apparatus
as that hereinbefore described and in the position originally occupied by the
photographic plate, the coloured picture is then reconstructed by exposing the slots
in the grating to a uniform source of white light, or another method may be
employed in which a lamp and condenser are placed at the back of the lantern slide,
the light issuing from the grating being thrown on a screen where the original
colours are found to be reconstituted.
The hereinbefore described analysing apparatus may be employed to produce
pictures showing interference colours in film backed by reflecting surface as
previously used.
In landscape photography where the grating cannot be conveniently arranged
sufficiently near the object being photographed, a pin hole camera may be employed
or the lens may be considerably stopped down, in order that both grating and
landscape may be approximately in focus.
A screen may be employed to absorb the ultra violet rays, to prevent their
reaching the sensitized plate; a cell containing sulphate of quinine in solution
may be employed for this purpose.
Referring to the accompanying sheet of drawings ;-
Figure 1 shows apparatus suitable for the photographing and reproduction of
still life studies in portraiture.
Figure 2 is a modification suitable for more varied work.
Figure 3 is an enlarged view of a portion of the grating.
Figure illustrates one manner in which a lens may be constructed to produce the
necessary dispersion without the use of a separate prism.

page_text: A is the grating an enlargement of a portion of which is given in Figure 3.
B is the lens or combination with analysing prism, C, forming a dispersed image
of the subject on the screen or sensitised plate at D E is a colour screen as usually
employed to obtain truly orthochromatic pictures, F represents a condensing
conibination used in conjunction with a source of light for reprojecting the picture
from the finished photograph a screen being placed close to the grating at A to
receive the picture.
In Figure 2 the picture is first projected on the grating by an additional lens
combination G diffusion of the image being avoided by the employment of a
condenser H.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is ;-
In a photographic apparatus the combination of a grating and prism substantially
as and for the purposes herein before set forth.
Luten
CHILLI
day on ou
1000.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.