Improvements in Photochromoscopes and Photochromoscope Cameras
Year: 1895

page_text: being date of first Foreign Application (in 3rd July; 1894
I
United States of America \
Date of Application (in United Kingdom), 1st Feb., 1895
Complete Specification Left; 6th Aug., 1895-Accepted, 11th Jan., 1896
Date of Application (in United Kingdom), 1st Feb., 1895
Complete Specification Left; 6th Aug., 1895-Accepted, 11th Jan., 1896
Improvements in Photochromoscopes and Photochromoscope
Cameras,
I, FREDERIC EUGENE IVES, of 2750 North Eleventh Street, in the City and
County of Philadelphia State of Pennsylvania one of the United States of
America, Photographer do hereby declare the nature of this invention to be as
follows:-
The term " photochromoscope I apply to an instrument intended to blend
together by optical means a series of images of the same subject which constitute
what I term a chromogram " and which are seen through different coloured
glasses or with different coloured lights.
A chromogram consists of a series (preferably three) of photographic positives
on glass or other transparent medium these positives being obtained from a
negative or negatives comprising a corresponding series of images of the same
subject where there are three images one of them should be obtained by rays
of light in proportion as they excite the fundamental red sensation, another by
rays of light in proportion as they excite the fundamental green sensation and
the third by rays of light in proportion as they excite the fundamental blue
or violet, sensation, such process forming the subject of my United States
Letters Patent No. 432,530 dated July 22, 1890. Rays of light passing through
three such images and through suitable colour screens will if so directed as to
accurately superpose the three images reproduce the natural colours of the.object
photographed.
In my United States Patent No. 475,084 dated May 17th 1892 and in my
corresponding British Patent No. 4606 dated 8th March 1892 I have shewn and
described an instrument which was capable of use as a photochromoscope but the
said patented instrument was of expensive construction and the object of my.
present invention is, primarily to so construct the instrument as, to very materially
cheapen the same and at the same time render it more acceptable by reason
of its, greater convenience, its effective lighting of the images and its provision
for the use of both eyes which permits of making the instrument stereoscopic,
a result which cannot be, attained in an instrument having but a single eye
piece.
'
A suitable casing is provided for the instrument which casing is preferably
hinged at the front lower corner to the front of a box or tray which serves as .
the base of the instrument and as a receptacle for the chromograms a pivotted.
.and slotted arm hung to the base tray serving in connection with a set screw on
the casing to adjust the latter to any angle which may be found to be best for
properly, transmitting, the light.

page_text: The top of the box comprises three steps for the support of the chromogram the
latter being made in three sections connected together by a flexible strip or cord
or strips or cords.
Each chromogram section consists of a transparent medium upon which the
photographic image is directly produced or it may consist of a strip of any
available material having the transparent film bearing the photographic image
secured to it in any suitable way.
Each chromogram section may have two images so as to permit of the stereo-
scopic use of the instrument the front of the casing having two openings and au
ordinary stereoscopic eye piece being mounted upon the underside of the casing so
as to be free to slide to and fro for focussing purposes. It will of course be
understood that both of the images formed upon or carried by each section of the
chromogram are exactly similar and also that the images of the three sections of
the chromogram are alike save as to the differences in gradations of light and
shade which constitute the colour record. For instance the images of one
chromogram section may represent the fundamental green sensation those of the
next section the fundamental blue sensation and those of the other section the
fundamental red sensation.
Each step of the casing has a strip serving as a gauge or stop for what may be
termed the "base edge" of each of the chromogram-sections and another strip or
lug serving as a gauge or stop for one end of the chromogram section. Hence
when each chromogram section is adjusted so as to bear against the stops
gf its respective step, the three sections will be so disposed that their images will
be accurately superposed when reflected so as to be viewed through the openings.
The reflecting devices consist of an opaque mirror and two transparent mirrors
these three mirrors being used to reflect the rays of light passing through the
images of the sections respectively of the chromogram the transparent mirrors
serving both as reflectors and transmitters of light.
Colour screens are also employed in connection with the three sections of the
chromogram one being the green screen, another the blue-violet screen and the
other the red screen.
The transparent mirrors may be plain, platinized or coloured. If plain, however,
the glasses would have to be slightly wedge shaped in order to prevent the double
reflection from both sides of the glass resulting in a double outline of the image.
The platinizing of the glass sufficiently overcomes the necessity for tapering the
same but I prefer to overcome this necessity by making the transparent mirrors of
coloured glass of such character that such portion of the rays they are intended to
reflect as pass into the glass will be absorbed thereby and not reflected from the
rear surface, for instance the mirror used in connection with the red screen may be
of cyan-blue colour and the mirror used in connection with the blue screen may be
of canary yellow so that each glass will be absorbent of all of the particular
quality of light which it is intended to reflect, but which is not reflected from its
front surface, the colouring of the transparent mirrors having no material modifying
effect upon the rays which should reach the eye from the mirror or mirrors in
the rear.
°
The colouring of the transparent mirrors may have an effect supplementary to
the green and blue violet screens or may even in some cases take the place of one
of said screens for instance, if the second transparent mirror be yellow and the
other transparent mirror be cyan-blue, the light passing through both will be green
and the green screen may not be necessary. The use of the three-colour screens is
however in all cases to be preferred in order to obtain with certainty the desired
purity and strength of colour. It is not necessary that the glasses should be
coloured in their substance, as the colouring may be in the form of a coating of
properly tinted collodion or varnish.
Platinized mirrors, although transparent, reflect more light than do plain or
coloured glasses and would be preferable to the latter if they could be made with
perfectly plane surfaces which however appears to be difficult if not impossible.

page_text: The casing may have but two steps, one section of the chromogram lying against
the front of the casing the mirror for it being an external mirror so that the rays
of light which illuminate the said section are reflected before passing through the
same instead of after such passage, as in the case of the other sections of the
chromogram.
In this instrument I can also substitute for the external mirror a
dead white reflector, which may if desired be detached from the casing and laid
upon the table in front of the instrument, but the mirror is preferable in order to
insure for the image of the green sensation light of the same intensity as that for
the other two images. This construction of the instrument necessitates a corre-
sponding 'alteration in the spacing of the sections of the chromogram and also a
reversal of the images of the first named section in respect to those of the other
sections.
Provision may be made for uniform spacing of the sections of the chromogram
the external mirror being considerably larger than in the instrument last herein-
before-described so that it can reflect the rays of light through both the first and
third sections of the chromogram, the rays after passing through the images of
the third section being again reflected first by an opaque mirror and then
by a transparent mirror. The images of the second section of the chromogram
intended for use in connection with this instrument are reversed relatively to the
others.
The instruments last described are more compact than that first described and
are therefore preferable on that account and further because they bring the eye
nearer to the chromogram and thus shew a larger image without the use of
magnifying lenses.
с
The instrument may have mirrors which instead of being arranged at an angle
of forty five degrees in respect of the horizontal as is presumed to be the case in
the instrument previously described, are only at an angle of twenty two and
one half degrees in respect to the horizontal the object of this disposal of the
mirrors being to increase the reflective power of the transparent mirrors, the
chromogram sections being arranged at an angle of 45 degrees in respect to
the horizontal. I may in this instrument however use a single chromogram the
slight distortion of the image due to the different distances of different parts of
the same from the eye not being sufficient to materially affect the accuracy of
the image and this distortion being capable of correction by a reverse distortion
of the images in the original negative.
In all of the instruments certain advantages are gained by placing a condensing
lens immediately behind each image of the chromogram but such lenses are not
necessary. When they are employed I prefer in some cases to use plano-convex
lenses and to cement the colour screen to the plane side of the lens.
Although I have described the sectional chromogram as having its sections
connected by strips of flexible material and although I prefer this method of
construction it will be evident that metallic hinges may be substituted for the
flexible strip as a ineans of connecting the chromogram section or sections
disconnected from each other and may be used in the instrument with equally good
results. It will be evident also that each of the forms of instrument which I have
described may be single and binocular, or single and monocular instead of
stereoscopic and by the use of suitable lenses and colour screens and the substitution
of plate holders for the chromogram holders either form of instrument may be
adapted for making the chromogram negative as well as for exhibiting the
chromogram.
The arrangement of images in steps and the reflection of the light passing
through these images by means of transparent mirrors is not new, but in the
only prior device of this kind with which I am familiar the steps were perpendicular
to the base of the instrument and the transparent mirrors were glasses with
parallel surfaces which doubled the outlines of the respective images. This taken
in connection with the inconvenience of the instrument rendered the same so
defective as to make it practically useless and the vertical arrangement of the

page_text: .
mirrors prevented the making of the instrument binocular or stereoscopic except by
duplication of its parts or enormous increase in size.
In all of the various forms of my instrument however what may be termed the
base edge of the chromogram or of each section of the chromogram is horizontal
and the images are situated one above another whereby I am enabled to bring the
. angles of illumination and vision into the most desirable relation to each other and
to the most convenient source of light, namely, a light sky seen through a window
and I am furthermore enabled to make the instrument binocular or stereoscopic
without complicating its construction or making it of inconvenient size, and I also
provide for the most convenient use of the folding chromogram while the use of
the coloured transparent mirrors effectually prevents any doubling of outline of the
images reflected thereby.
Dated this 1st day of February 1895.
•
Improvements in Photochromoscopes and Photochromoscope
Cameras.
1, FREDERIC EUGENE IVES of 2750 North Eleventh Street in the City and
County of Philadelphia, State of Pennsylvania, one of the United States of
America, Photographer, 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 :--
The term "photochromoscope" I apply to an instrument intended to blend
together, by optical means, a series of images of the same subject, which series of
images constitute what I term a "chromogram" and which are seen through
different coloured glasses or by means of different coloured lights.
The series of images constituting the chromogram consists preferably of three
photographic positives on glass, or other transparent medium, these positives being
obtained from a negative, or negatives, comprising a corresponding series of images
of the same subject.
I will, for the purposes of description, presume that three images are used.
One of the said images should be obtained by rays of light in proportion as they
excite the fundamental red sensation, another by rays of light in proportion as
they excite the fundamental green sensation, and the third by rays of light in
proportion as they excite the fundamental blue, or violet sensation, such process
forming the subject of United States Letters Patent No. 432,530 dated July 22,
1890 granted to me.
Rays of light passing through three such images and through suitable colour
screens will, if so directed, as to accurately superpose the three images, reproduce
in its natural colours to the eye of the observer a true and realistic image of the
object photographed.
In British Letters Patent No. 4606 dated 8th March 1892, granted to me I
have shewn and described an instrument capable of use as a photochromoscope,
but the said instrument is of complicated and expensive construction and the
principal object of my present invention, is to so construct an instrument for the
purpose that it is materially simpler and cheaper and more convenient besides
giving very effective lighting of the images, and its adaptation for the use of both
eyes permits of making the instrument stereoscopic, a result which of course cannot
be attained in an instrument having but a single eye piece.

page_text: In the accompanying drawings
Figure 1 is a perspective view of a photochromoscope embodying my present.
invention.
Figure 2 is a vertical section of the same.
Figure 3 is a perspective view of a chromogram intended for use with the said.
instrument, the chromogram being shown extended.
Figure 4 is a perspective view shewing the chromogram folded.
Figure 5 is a vertical section of another form of the photochromoscope which
is, for some reasons, preferable to that illustrated in Figures 1 and 2.
Figure 6 is a view of a chromogram adapted for use with the instrument shewn
in Figure 5.
Figure 7 is a vertical section of a slightly modified instrument of the class-
represented in Figure 5.
Figure 8 is a view of a chromogram intended for use with the instrument shewn.
in Figure 7.; and:-
:
Figure 9 is a vertical section of another form of the instrument.
"
'
J represents the casing of the instrument which is preferably hinged at the
lower forward edge to the front of a box or tray J¹ which serves as the base of
the instrument, and may also serve as. a receptacle for the chromograms, a pivotted
and slotted arm a centered to the base tray J' serving, in connection with a set.
screw a passing through the slot in the arm and screwing into the casing J, to-
secure the said casing at any angle which may be found to be best for properly
transmitting the light.
7
The top of the casing J is formed with three steps A. B and D for the support of
the chromogram, which is made in three sections A', B', D', connected together by
flexible strips or cords 6 of which there may be one, or more, suitably disposed,.
two of these strips or cords, one near each edge of the chromogram, being shewn
in the drawings..
.'1
Each section of the chromogram consists of a glass or other transparent plate
upon which the photographic image is directly produced, or it may have the
transparent film bearing the photographic image secured to it in any suitable-
way.
..
: :
In the chromograms shewn in Figures 3 and 4 each chromogram section has two
images to suit the stereoscopic arrangement of the instrument, which is that I
have illustrated, the front of the casing J having two openings d, an ordinary
stereoscopic eye piece F being connected to the casing J, so that it can be slidden.
to and fro for focussing. purposes.
:
It will, of course, be understood; that both of the images formed upon, or
carried by, each section of the chromogram are exactly similar except as to the-
slight difference in perspective which characterizes the two images of a stereoscopic
photograph owing to the difference of point of view and also that the images of
the three sections of the chromogram are alike, save as to the differences in
gradations of light and shade which constitute the colour record, for instance,.
the images of the chromogram section A' may represent the fundamental green
sensation, those of the next section B the fundamental blue or violet sensation,.
and those of the section D' the fundamental.red sensation.
Each step of the casing J has a strip f serving as a gauge or stop for the-
rearward edge of each of the chromogram.sections to bear against and another
strip or lug.g serves as a gauge or stop for one end of each of the chromogram
sections, so that when each chromogram section is adjusted so as to bear against.
the stops and g of its step, the three sections will be so situated that their
images will be accurately superposed when reflected for being viewed through the
openings d.
'
The reflecting devices consist of an opaque mirror A² and two transparent.
mirrors, B2, and D2, these three mirrors being used to reflect the rays of light
passing, through the images of the sections A¹ B' and D' respectively, of the

page_text: transpartum Sciving both as relectors and transmitters o
light.
A B and D³ represent the respective colour screens employed in connection with
the three sections A' B₁ and D' of the chromogram, each of these screens being
coloured to accord with the respective colour sensation represented by its section
of the chromogram.
In the present case therefore A³ is a green screen, B³ a blue-violet screen,
and D³ a red screen.
The transparent mirrors B2 and D2 may be plain, platinized, or coloured. If
plain, however, the glasses would have to be slightly wedge shaped in order to
prevent the double reflection from both sides of the glass, resulting in a double
outline of the image.
The platinizing of the glass sufficiently overcomes the necessity for tapering the
same, but I prefer to overcome this necessity by making the transparent mirrors of
coloured glass of such character that such portion of the rays they are intended
to reflect as pass into the glass will be absorbed thereby, and not reflected from the
rear surface, for instance, the mirror D2, used in connection with the red
screen D³, may be of cyan-blue colour, and the mirror B2 used in connection
with the blue screen may be of canary yellow, so that each glass will be absorbent of
all of the particular quality of light which it is intended to reflect, but which is
not reflected from its front surface, the colouring of the transparent mirrors having
no material modifying effect upon the rays which should reach the eye from the
mirror or mirrors in the rear.
The colouring of the mirrors B² and D2 may have an effect supplementary to the
colour screens A³ and B³ or may even, in some cases, take the place of one of said
screens, for instance, if the mirror B2 be yellow, and the mirror D³ cyan-blue, the
light passing through both will be green, and the green scrcen A may not be
The use of the three colour screens is, however, in all cases to
be preferred in order to obtain with certainty the desired purity and strength of
colour.
necessary.
It is not necessary that the glasses should be coloured in their substance,
as the colouring may be in the form of a coating of properly tinted collodion, or
varnish.
Platinized mirrors, although transparent, reflect more light than do plain or
coloured glasses and are for that reason preferable to the latter if they be made
with perfectly plane surfaces, which is however, difficult, if not impossible.
In the form of instrument shewn in Fig. 5 the casing J has but two steps and
the section A¹ of the chromogram lies against the forward side of the casing,
the mirror A being an external mirror so that the rays of light which
illuminate the said section A¹ are reflected by the mirror A² before they pass
through the said section and the colour screens, instead of after such passage, as in
the case of the sections B1 and D₁ of the chromogram.
In this instrument I can also substitute for the external mirror A2 a dead white
reflector, which may, if desired, be detached from the casing and laid upon the
table forward of the instrument, but the mirror is preferable, in order to insure
for the image of the green sensation, light of the same intensity as that for the
other two images.
The construction of the instrument as shown in Figure 5 necessitates the spacing
of the sections of the chromogram in the manner shown in Figure 6, and also a
reversal of the images of the section A' in respect to those of the sections B' and D'
as also shewn in Figure 6.
In the form of instrument shewn in Figure 7 provision is made for uniform
spacing of the sections of the chromogram as shown in Figure 8, and in this case
the mirror or reflector A² is considerably larger than in the instrument shown in
Figure 5, so that it can reflect the rays of light through both sections A¹ and D' of
the chromogram, the rays after passing through the images of the section D' being

page_text: again reflected first by the opaque mirror D* and then by the transparent
mirror D².
The images of the section B³ of the chromogram intended for use in connection
with this instrument are reversed in respect to those of the sections A¹ and D' as
shewn in Figure 8.
The instruments shown in Figures 5 and 7 are more compact than that shown in
Figures 1 and 2, and they bring the eye nearer to the chromogram and thus show
a larger image without the use of magnifying lenses.
In Figure 9 I have shown a form of instrument in which the mirrors, instead of
being arranged at an angle of 45 degrees to the base of the casing J as in the
instruments previously described, are only at an angle of 22 degrees, the object of
this disposal of the mirrors being to increase the reflective power of the transparent
mirrors, the chromogram sections being arranged at an angle of 45 degrees to the
horizontal or base of the casing J. I may in this instrument however use a
chromogram consisting of one piece as represented by dotted lines, the slight
distortion of the image due to the different distances of different parts of the same
from the eye not being sufficient to materially affect the accuracy of the image
and this distortion being capable of correction by a reverse distortion of the images
in the original negative.
In the instrument shown in Figure 9 I have shown condensing lenses G and G¹,
and in all of the instruments, certain advantages are gained by placing a condensing
lens immediately behind each image of the chromogram, but such lenses are not
essential. When they are employed I prefer in some cases to use plano-couvex
lenses and to cement the colour screen to the plane side of the lens.
Although I have described the sectional chromogram as having its sections
connected by strips of flexible material, and although I prefer this method of
connection, it will be evident that the connection may be effected in any other
convenient way for instance by hinges. It will be evident also that each of the
forms of instrument which I have described may be single and binocular, or single
and monocular, instead of stereoscopic, and by the use of suitable lenses and colour
screens and the substitution of plate holders for the chromogram holders either
form of instrument may be adapted for making the chromogram negative as well as
for exhibiting the chromogram.
The arrangement of images in steps and the reflection of the light passing
through these images by means of transparent mirrors is not new, but in the only
prior device of this kind of which I am aware the steps were perpendicular to the
base of the instrument and the transparent mirrors were uncoloured glasses with
parallel surfaces which doubled the outlines of the respective images.
This taken in connection with the inconvenience of the instrument rendered the
same so defective as to make it practically useless, and the perpendicular arrange-
ment of the mirrors prevented the instrument from being made binocular or
stereoscopic except by duplication of its parts or enormous increase in size.
In all of the various forms of my instrument, however, what may be termed the
base edge of the chromogram or of each section of the chromogram is horizontal,
and the images are situated in places one above the other, whereby I am enabled
to bring the angles of illumination and vision into the most desirable relation to
each other and to the most convenient source of light, for instance a light sky
seen through a window, and I am furthermore enabled to make the instrument
binocular or stereoscopic without complicating its construction or making it of
inconvenient size, and 1 also provide for the inost convenient use of the folding
chromogram while the use of the coloured transparent mirrors effectually prevents
any doubling of outline of the images reflected thereby.
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. A photochromoscone or photochromoscope camera having a series of inclined

page_text: reflecting mirrors some or all of which are transparent a series of colour screens
and a casing so formed as to carry or support the sections of the chromogram or
plates or the single form of chromogram or plate so that the images are one
above another substantially as hereinbefore described.
2. A photochromoscope or photochromoscope camera comprising a casing
having a series of inclined mirrors as described, some or all of which are trans-
parent, a series of colour screens, a series of chronogram or plate supports one
above another also as described and means for varying and fixing the angle of the
instrument substantially as herein before described.
3. A chromogram consisting of a series of sections united so as to be capable
of folding one upon another the images of the sections being identical in size and
perspective but with differences in gradations of light and shade which differences
constitute a colour record substantially as hereinbefore described.
4. A chromogram consisting of a series of pairs of images the images of each
pair being alike except for the difference of perspective which characterizes the
images of a stereoscopic pair the images of each of pair being identical in size and
perspective but with differences in gradations of light and shade which differences
constitute a colour record substantially as herein before described.
5. A photochromoscope or photochromoscope camera comprising a casing having
a. series of seats or steps one above another for a sectional chromogram or plates
. a series of inclined mirrors and a series of colour screens the chromogram or plate
supports and mirrors being so arranged that the instrument is adapted for use in
connection with a reflector or reflectors substantially as hereinbefore described
with reference to Figs. 5 and 7 whereby one of the images is viewed direct and
the others by reflection.
6. A binocular or stereoscopic photochromoscope or photochromoscope camera
having in combination with a binocular eye piece a chromogram or plate support
or chromogram or plate supports so disposed that the pairs of images will be
. situated one above another, a series of colour screens and a series of mirrors
some or all of which are transparent the said mirrors being inclined and
situated one behind another in the line of sight substantially as hereinbefore
described.
7. A photochromoscope or photochromoscope camera comprising a casing having
a series of seats or steps one above another for a sectional chromogram or plate
a series of inclined mirrors some, or all, of which are transparent the said mirrors
being situated one behind another in the line of sight aud inclined in a horizontal
plane substantially as herein before described.
Dated this 6th day of August 1895.
JOHNSONS & WILLCOX,
Agents.