Improvements in Photochromoscopes and Photochromoscope Cameras.
Year: 1895

page_text: Date of Application, 21st Feb., 1895
Complete Specification Left, 21st Nov., 1895-Accepted, 28th Dec., 1895
PROVISIONAL SPECIFICATION.
Improvements in Photochromoscopes and Photochromoscope
Cameras.
I FREDERIC EUGENE IVES of 2750 North Eleventh Street in the City of
Philadelphia State of Pennsylvania, United States of America Photographer do
hereby declare the nature of this invention to be as follows:-
One object of my invention is to so construct a photochromoscope or photo-
chromoscope camera that by means of such camera three images side by side upon
the same sensitive plate or film can be produced, or in the case of the photo-
chromoscope, a plate having the images so disposed can be used, a further object
being to employ a fixed focus or extension camera, and to render unnecessary any
change in the character of the reflecting mirrors in order to properly focus the
images for objects at any distance, and a still further object being to provide
means for properly retaining the reflecting mirrors in place and yet permit of the
ready removal and replacing of the same as may be required for proper cleansing
or repair.
I will describe my invention with reference to the accompanying drawings of
which
Figure 1 is a. perspective view of a photochromoscope camera constructed in
accordance with my invention.
Figure 2 is a sectional plan view of the same.
Figure 3 is a diagram illustrating the arrangement of reflecting mirrors
employed.
Figures 4 and 5 are similar diagrams illustrating modified combinations of
mirrors which may be used; and
Figure 6 is a sectional view on a smaller scale of a modified form of the
camera.
In Figures 1 and 2, A represents a box or casing of appropriate size and shape
preferably divided internally into three portions by means of longitudinal
partitions a a, this box being provided at its rear end with any suitable means. for
supporting and retaining the sensitive plate or film and its holder, and having at the
front end three objective lenses B, D and F arranged side by side and each
adapted to project an image onto its respective portion of the sensitive plate
or film supported at the rear end of the camera, a suitable color screen
being employed in connection with each of the objective lenses, thus the color
screen B employed in connection with the lens B may be a green screen, the
screen D employed in connection with the lens D may be blue and the screen F¹
employed in connection with the lens F may be red.
These color screens are held in place by means of springs b against a perforated
partition plate in the rear of the lens frames so that each screen can be readily
removed for cleaning and as readily replaced after being cleaned, the top of the
casing A being hinged and normally held in place by a suitable catch so that
on releasing the catch the top can be raised to permit access to the color screens
and the interior of the camera.
Hinged to the front end of the casing A at one side of the latter is another
casing A open on that side which is towards the casing A, this casing A' carrying
the series of transparent and opaque mirrors whereby the incident rays are divided

page_text: and renected so as to be thrown. through the, three objective lenses and onto the
different portions of the sensitive plate or film.
The system of mirrors shown in Figures 2 and 3 comprises two transparent
mirrors d and f and four opaque mirrors hi and m the mirrors d f and g all being
in the same direction and at the same angle in respect to the line of the incident
rays and the three mirrors hi and m being, inclined in the same direction and at
the same angle in respect to the line of the incident rays, the angle of the three
mirrors and m being the reverse of the angle of the mirrors d f and g.
The mirrors g h and m have but one reflecting face while the mirror i reflects
from both its front and rear faces.
The mirror d is directly in line of the incident rays and the mirror is behind
the same and in front of the central lens D. The mirror faces the back of the
mirror and is in the rear of the mirror f, the mirror o is in front of the lens B
and the mirror m fares the front of the mirror i and is in front of the lens F.
The incident rays striking the mirror d are divided a portion of the rays being
transmitted through said mirror onto the front of the mirror i and being thence
reflected onto the mirror m and from the latter through the lens F. Those rays
which are reflected from the mirror d strike the mirror fand are again divided, a
portion of the rays being transmitted through the said mirror onto the mirror g and
being by the latter reflected through the lens B, while those rays which are
reflected by the mirror f strike the mirror h and are thence reflected onto the back
of the mirror i and by the latter through the central lens D.
The various mirrors are so disposed in respect to each other that the length of
each ray from the point of impact upon the mirror d to the surface of the sensitive
plate or film shall be exactly the same, that is to say, the rays transmitted to the
central portion of the sensitive plate shall in their four reflections 1. 2. 3. 4. Figure 3
traverse the same lateral distance as the rays for one end of the plate in their two
reflections 1, 5, or the rays for the other end of the plate in their two reflections 6, 7,
the longitudinal distance travelled by the rays forming each image being of course
the same in all three images.
22
By thus providing for a single lateral reflection of the rays which form the outside
images on the plate or film, and for a double lateral reflection of the rays which
form the central image, I am enabled to form three precisely similar images side
by side upon the same plate and am thus enabled to produce comparatively large
images without the use of an inordinately large plate thus overcoming an objection
to the instrument shewn in my Specification to Letters Patent dated, 8th day of
March 1892 No. 4606 in which the mirrors and lenses were so disposed as to produce
a trefoil arrangement, of the images upon the plate thus necessitating the use of a
square instead of an oblong plate or film and involving the loss of a comparatively
large area of the plate, or in other words only a partial covering of the plate by the
three images, whereas in the present camera the three images occupy the entire
plate or film.
In connection with each of the lenses B. D and F a perforated diaphragm: for
properly limiting the transmission of light to the lens is employed, the diaphragm 53
of the lens B being situated in front of the said lens and between the same and
the mirror g while the diaphragm d for the lens D. is arranged between the
mirrors hand and the diaphragm 2 for the lens F is arranged between. the
mirrors and m.
38
Each of the mirrors is held in contact with a suitable stop block n at top or
bottom by means of a spring p so that while the mirror is properly retained in its
rélation to the other parts of the instrument when in use it can be readily removed
or replaced when cleaning or repair becomes necessary, ready access to the mirrors
and diaphragms being permitted on swinging open the casing A' which is normally
held in a closed position by means of a spring catch s.
The transparent mirrors d and f are preferably of clear glass having plane
surfaces which surfaces may or may not be exactly parallel with each other
although to avoid a doubling of outlines in the images on the sensitive plate or film

page_text: the plane surfaces must ordinarily be exactly parallel to each other for photo-
graphing distant objects, but inclined to each other, so as to make the mirror very
slightly wedge shaped, for nearer objects the inclination of the surfaces to each
other necessary to avoid doubling of outline in the images being different for every
different distance of object requiring a change in the extension of the camera to
obtain a sharp focus.
Owing to the trouble and expense of changing the transparent mirrors for
objects at different distances I use a camera with a fixed focus or fixed extension
and employ transparent mirrors adapted to give images free from doubling of
outline at that focus or extension, and focus for objects at various distances by
means of a focusing lens or lenses placed between the object and the first of the
transparent mirrors d.
I prefer to employ for focusing purposes a combination of one positive and one
negative lens adjustable in respect to each other the said lenses at one adjustment,
neutralizing each other or securing a sharply focused image in the camera for
objects at one distance, but altering the focus of the camera when separated or
brought nearer together. I prefer a plano-convex positive lens w fixed to the
casing A and a plano-concave negative lens w¹ carried by the head a¹ of an
adjustable slide x. between which head and the front of the casing A¹ is an ordinary
form of bellows y to exclude the light.
If, when the lens wo¹ is brought close to the lens w the lenses neutralise each
ether, they have, when separated, a positive focus which becomes shorter and
shorter as the separation is increased, thereby bringing nearer objects into focus
without disturbing the relation between the mirrors, objective lenses and sensitive
plate or film of the camera, and thus focusing for objects at all distances without
change of camera extension and without any doubling of outline in the images
produced.
This focusing device is also applicable to my former camera, or to an
ordinary fixed focus camera for producing a single image and may be so
employed if desired, and while it is employed by preference in my improved
triple camera with its mirrors as described, it is not absolutely essential in that
cainera since a single focusing lens adjustable in respect to the mirror d might be
used if desired, for instance, if the camera without the focusing lens be made to
focus normally without any doubling of outline in the images for a near object, say
one or two feet away, the focusing lens may be concave or negative in order to
bring more distant objects into focus without changing the camera extension,
while, if on the other hand, the camera be made to focus normally for distant
objects, a convex or positive focusing lens may be employed in order to focus for
nearer objects. In all cases however, the focusing lens or one of them, if two are
used, should be made adjustable from and towards the first of the transparent
mirrors d so as to ensure accurate focusing.
It is also possible, in case a comparative narrow angle of view and a certain
amount of pin cushion distortion are permissible, to omit the lenses B. D and F
and use only a positive lens in advance of the mirror d this lens both forming
and focusing the images. Such a construction is illustrated in Figure 6.
Although I have described my invention as applied to a photochromoscope
camera it will be evident that it is applicable to a photochromoscope as well,
by a simple reversal of the direction of the light rays, a plate or film with the
positive images being located at the plate holder end of the casing A while
the eye is applied to the focusing len's or lenses or to the aperture in advance of
the first mirror d. Although I prefer the arrangement of mirrors shewn in
Figures 2 and 3, other arrangements of mirrors may be employed which will
effect the same result, that is to say, the double latéral reflection of the central
rays and the single lateral reflection of the side rays so as to insure the uniform
length of rays for all of the' images in their transmission from the primary mirror
of the series to the sensitive plate or film.
In Figures 4 and 5 I have shewn two modified arrangements of mirrors, that.

page_text: shewn in Figure 4 comprising two transparent mirrors d' and f' and six opaque
mirrors g¹² and m' the mirrors dif' and being arranged one behind
the other in the direction of the incident rays, the mirror g' facing the mirror d', the
mirror m facing the mirror f1 and the two mirrors and 2 facing respectively the
mirrors and the course of the rays being indicated by the respective dotted
lines.
In Figure 5 I have shewn a combination comprising transparent mirrors d³
and and opaque mirrors g³ ³ and m³ the mirrors d³ ³ and being arranged
one behind the other in the line of the incident rays, the mirror m³ facing the
mirror d³, the transparent mirrory and opaque mirror g³ facing the mirror and
the mirror * facing the mirror and being arranged at an angle the reverse of the
mirror 3 so as to receive the reflected rays therefrom.
In the case of the photochromoscope the colour screen may if desired, be outside
of the instrument, that is to say, interposed between the images and the source of
Fight, or colour screens may be combined with the sensitive plate or film, or the
latter itself may be dyed or coloured so that each image constitutes its own colour
screen.
Dated this 21st day of February 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.
Improvements in Photochromoscopes and Photochromoscope
Cameras.
1, FREDERIC EUGENE IVES, of 2750 North Eleventh Street, in the City of
Philadelphia, State of Pennsylvania, United States of America, Photographer, do
hereby dcclare the nature of my invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the following
statement:-
One object of my invention is to so construct a photochromoscope, or photo-
chromoscope camera, that by means of such camera three images can be produced
side by side upon the same sensitive plate or film or in the case of the photo-
chromoscope a plate having the images disposed in the said manner can be used; a
further object being to employ a fixed focus, or extension, camera and to render
unnecessary any change in the character of the reflecting mirrors in order to
properly focus the images for objects at any distance.
:-
I will describe my invention with reference to the accompanying drawings
Figure 1 is a perspective view of the casing of a photochromoscope camera
and Figure 2 is a sectional plan of the same shewing the construction in accordance
with my invention.
Figure 3 is a diagram illustrating the arrangement of reflecting mirrors
employed.
Figures 4 and 5 are similar diagrams illustrating modified combinations of
mirrors which may be used and
Figure 6 is a sectional view (drawn to a smaller scale) of a modified construction
of the camera.
In Figures 1 and 2 A represents a box, or casing of appropriate size and shape
preferably divided internally into three portions by means of longitudinal
partitions a a; this box being provided at its rear end, with any suitable means for
supporting, and retaining, the sensitive plate, or film, and its holder, and having at
the front end three objective lenses B, D and F arranged side by side, and each
adapted to project an image onto its respective portion of the sensitive. plate, or

page_text: film supported at the rear end of the camera, a suitable colour screen being
employed in connection with each of the objective lenses. Thus the colour
screen B1 employed in connection with the lens B, may be a green screen, the
screen D employed in connection with the lens D, may be blue, and the screen F¹
employed in connection with the lens F, may be red.
These colour screens are held in place by means of springs b against a perforated
plate in the rear of the lens frames so that each screen can be readily removed
for cleaning, and be as readily replaced after being cleaned, the top of the casing A
being hinged, and normally held in place by a suitable catch 62 (Figure 1) so that,
on releasing the said catch, the top can be raised to permit access to the colour
screens and the interior of the camera,
Hinged to one side of the front end of the casing A is another casing A' open
on that side which is towards the casing A, the casing A' carrying the series of
transparent and opaque mirrors whereby the incident rays are divided and reflected
so as to be thrown through the three objective lenses and onto the different portions
of the sensitive plate, or film.
The system of mirrors shewn in Figures 2 and 3 comprises two transparent
mirrors d and f and four opaque mirrors ghi and m, the mirrors d f and g all being
inclined in the same direction, and at the same angle relatively to the line of the
incident rays, and the three mirrors hi and m being inclined in the same direction,
and at the same angle relatively to the line of the incident rays, the angle of the
three mirrors hi and m being the reverse of the angle of the mirrors d f and g.
The mirrors g h and m have but one reflecting face while the mirror i reflects
from both its front and rear faces.
The mirror d is directly in line with the incident rays, and the mirror i is behind
the same, and in front of the ceutral lens D. The mirror h faces the back of the
mirror and is in the rear of the mirror f. The mirror g is in front of the lens B
and the mirror m faces the front of the mirror i and is in front of the lens F.
The incident rays striking the mirror d are divided, a portion of the rays being
transmitted through the said mirror d onto the front of the mirror i and being
thence reflected onto the mirror m and from the latter through the lens F.
Those rays which are reflected from the mirror d strike the mirror f and are
again divided, a portion of the rays being transmitted through the said mirror onto
the mirror g and being by the latter, reflected through the lens B, while those rays
which are reflected by the mirror f strike the mirror and are thence reflected onto
the back of the mirror i and by the latter through the central lens D.
The various mirrors are so disposed in respect to each other that the length of
each ray from the point of impact upon the mirror d to the surface of the sensitive
plate, or film, shall be exactly the same, that is to say. the rays transmitted to the
central portion of the sensitive plate, shall in their reflections traverse the same
lateral distance as the rays for each end portion of the sensitive plate in their
reflections the longitudinal distance travelled by the rays forming each image being
of course the same in all three images.
By this means I am enabled to form three precisely similar images side by side
upon the same plate, and am thus enabled to produce comparatively large images
without the use of an inordinately large plate thus overcoming an objection to the
instrument shewn in the Specification of Letters Patent Number 4606 dated the
8th day of March 1892 in which the mirrors and lenses were so disposed as to
produce a trefoil arrangement of the images upon the plate, thus necessitating the
use of a square instead of an oblong plate or filin and involving the loss of a
comparatively large area of the plate, or, in other words, only a partial covering of
the plate by the three images, whereas in the camera according to my present
invention the three images occupy the entire plate or film.
In connection with each of the lenses B, D and F a perforated diaphragm for
properly limiting the transmission of light to the lens, is employed, the
diaphragmn 63 of the lens B being situated in front of said lens and between the
same and the mirror g while the diaphragm d² for the lens D is situated between

page_text: the mirrors and i and the diaphragm ƒ for the lens F. is situated between the
mirrors and m.
Each of the mirrors is held in contact with a suitable stop biock n at top, or
bottom, by means of a spring p so that while the mirror is properly retained in its
relation to the other parts of the instrument when in use, it can be readily removed,
or replaced, when cleaning, or repair, beconies necessary, ready access to the
mirrors and diaphragms being permitted on swinging open the casing A' which is
normally held in a closed position by means of a spring catch s.
The transparent mirrors d and fare preferably of clear glass, having plane
surfaces, which surfaces may, or may not, be exactly parallel with each other,
although, to avoid a doubling of outlines in the images on the sensitive plate, or
film, the plane surfaces must ordinarily be exactly parallel to each other for
photographing distant objects, but inclined to each other, so as to make the mirror
very slightly wedge shaped, for nearer objects, the inclination of the surfaces to
each other, necessary to avoid doubling of outline in the images, being different
for every different distance of object requiring a change in the extension of the
camera to obtain a sharp focus.
To obviate the trouble and expense of changing the transparent mirrors for
objects at different distances I use a camera with a fixed focus, or fixed
extension, and I employ transparent mirrors adapted at that fociis, or extension to
give images free from doubling of outline and I focus for objects at various
distances by means of a focusing lens, or lenses, placed between the object and the
first of the transparent mirrors d.
I prefer to employ, for focusing purposes, a combination of one positive lens, and
one negative lens, adjustable in respect to each other, the said lenses at one
adjustment, neutralizing each other, or securing a sharply focussed image in the
camera, for objects at one distance, but altering the focus of the camera when
separated, or brought nearer together. I prefer a plano-convex positive lens w
fixed to the casing A' and a plano-concave negative lens w' carried by the head al
of an adjustable slide a, between which head and the front of the casing A¹ is an
ordinary form of bellows y to exclude the light.
If, when the lens w¹ is brought close to the lens wo, the lenses neutralise each
other, they have, when separated, a positive focus which becomes shorter and
shorter, as the separation is increased, thereby bringing nearer objects into focus
without disturbing the relation between the mirrors, objective lenses, and sensitive
plate, or film, of the camera, and thus focusing for objects at all distances without
change of camera extension, and without any doubling of outline in the images
produced.
This focusing device is also applicable to my former camera, or to an ordinary
fixed focus camera, for producing a single image, and may be so employed if
desired, and, while it is eniployed by preference in my improved triple camera,
with its mirrors as described, it is not absolutely essential in that camera, sincé a
single focusing lens, adjustable in respect to the mirror d may be used if desired ;
for instance if the camera without focusing lens, be made to focus normally without
any doubling of outline in the images for a near object (say one, or two, feet away)
the focusing lens may be concave, or negative, in order to bring inore distant
objects into focus without changing the camera extension while, if, on the other
hand, the camera be made to focus normally for distant objects, à convex, or
positive, focusing lens may be employed in order to focus for nearer objects. In
all cases, however, the focusing lens or one of them if two be used, should be made
adjustable from, and towards, the first of the transparent mirrors d, so as to insure
accurate focusing.
It is also possible in case a comparatively narrow angle of view and a certain
amount of " pin cushion" distortion are permissible, to omit the lenses B, D, and F,
and use only a positive lens in advance of the mirror d, this lens both forming, and
focusing, the images. Such a construction is illustrated in Figure 6.
Although I have described my invention as applied to a photochromoscope

page_text: camera it will be evident that it is applicable to a photochromoscope as well,, by a
simple reversal of the direction of the light rays, a plate, or film, with the positive
images, being situated at the plate, holder end of the casing A, while the eye is
applied to the focusing lens or to, the aperture in advance of the first mirror d., or
to the lenses or apertures if the arrangement be duplicated to constitute a stereoscopic
instrument.
Although I prefer the arrangement of mirrors shewn in Figures 2 and 3, other
arrangements of mirrors may be employed which will effect the same result, that is
to say, the doubling of the lateral reflection of the side rays, so as to insure the
uniform length of rays for all of the images in their transmission from the primary
mirror of the series to the sensitive, plate, or film.
In Figures 4 and 5; I have shewn two. modified arrangements of mirrors, that
shewn in Figure 4 comprising two transparent mirrors d' and fl and six opaque
mirrors g h 22 and m the mirrors d' f¹ and being one behind the other in
the direction of the incident rays, the mirror gl facing the mirror d', the mirror m',
facing the mirror f, and the two mirrors and h² facing respectively the mirrors ¿¹
and the course of the rays being indicated by the respective dotted lines.
In Figure 5 I have shewn a combination comprising transparent mirrors d³ and ƒ³
and opaque mirrors g³ ³ it and m³ the mirrors d³ ³ and being arranged one
behind the other in the line of the incident rays, the mirror m³, facing the
mirror d³ the transparent mirror f³, and opaque mirror g³, facing the mirror and
the mirror h, facing the mirror 4, and being arranged at an augle the reverse of
the mirror f so as to receive the reflected rays therefrom.
In the case of the photochromoscope the colour screens may, if desired, be
outside the instrument; that is to say, interposed between the images and the
source of light, or colour screens may be combined with the sensitive plate, or
film, or the latter itself may be dyed or coloured, so that each image constitutes
its own colour screen.
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
-
1. In a photochromoscope, or photochromoscope camera, the combination of a
casing, the lens, or lenses, and a series of mirrors, some of which are transparent,
these mirrors being so disposed as to provide for the transmission of rays of light
from, or to produce, three images situated side by side in the same plane, the rays
for the central image being so reflected laterally that the length of the rays for all
the images is the same substantially as hereinbefore described.
2. In a photochromoscope, or photochromoscope-camera, the combination of the
casing having a fixed extension, a series of mirrors, some of which are transparent,
the said mirrors being so disposed as to provide for the transmission of rays of
light from or to produce three images situated side by side, and a focusing
lens, or focusing lenses, arranged in advance of the first mirror of the series
substantially as herein before described.
3. In a photochromoscope, or photochromoscope camera, the combination of the
casing having a fixed extension an objective lens, or objective lenses for focusing
the image at such fixed extension of the camera a series of mirrors, some of which
are transparent, the said mirrors being so disposed as to provide for the transmission
of rays of light from, or to produce three images, and a pair of focusing lenses
situated in advance of the objective lens, or lenses, and of the primary mirror of
the series, one of the said focusing leuses being positive and the other negative,
and one being adjustable relatively to the other; substantially as hereinbefore
described.
4. The combination of a photochromoscope camera having a fixed extension
and an objective lens, or objective lenses, for focusing the image at such fixed
extension of the camera, with a focusing device situated in advance of the said
objective lens, or lenses, and comprising a fixed positive lens and a negative

page_text: lens, mounted in advance of the positive lens, and adjustable relatively thereto
substantially as hereinbefore described.
5. In a photochromoscope camera, the combination of the casing having three
objective lenses so situated as to form images side by side on the same sensitive
plate, or film, a series of mirrors some of which are transparent, the said mirrors
being so arranged as to divide the incident rays and project them through the
three objective lenses, and a focusing lens, or lenses, situated in advance of the
primary mirror of the series substantially as herein before described.
Dated this 21st day of November 1895..
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.