Improvements in Photographic Apparatus.
Year: 1892

page_text: Complete Specification Left, ord ma
PROVISIONAL SPECIFICATION.
Improvements in Photographic Apparatus.
I, ALBERT DUBOSCQ of 55 Rue St. Jacques, Paris, France, do hereby declare
the nature of this invention to be as follows:-
This invention relates to improvements in photographic apparatus and consists
in applying to a photographic camera an optical apparatus constituting a telescope.
This apparatus allows of a direct photographic reproduction of the image of
objects situated at a considerable distance being obtained of such a size as to render
the operation known as enlarging unnecessary.
This apparatus may be applied to photographing terrestrial objects at great
distances and also celestial bodies and may advantageously be used for military and
naval purposes.
Referring to the accompanying drawing
Figs. 1 and 2 are diagrammatic views illustrating the principle upon which my
invention is based.
Suppose the object A B to he photographed to be situated at a very great
distance from an achromatic lens G of very long focus and forming the object
glass of a telescope; then there will be formed at a ba very small and very brilliant
inverted image of the object A B. Now suppose an achromatic lens D of very
short focal length be located in such a manner that the image at ab shall be situated
in front of its principal focus, then there will be formed on the focussing screen of
a camera an enlarged inverted image A' B¹ of the image at a b. This image A¹ B¹
will always be sharp, provided the focussing screen is situated beyond the point of
intersection of the rays from the lens D whatever may be the distance between
the focussing screen and the lens D, and the greater the distance between the
focussing screen and the lens the larger will be the image A' B'. It will be seen
that the image A' B¹ of ab formed on the focussing screen will be reversed, con-
sequently the object A B will be seen in its natural position.
An important feature of this invention is the addition of a third lens E (Fig. 2)
which may be termed a search, field or enlarging lens and which has a very short
focus. This lens E is located between the image at a band the lens D, the focus
of which it shortens, and consequently increases its enlarging power. The lens E
receives the rays coming from the objective G, and causes them all to pass into the
lens D, thereby increasing the light and the extent of the field. By suitable
shifting the lens E, it may be made to serve for focussing on the focussing screen
without altering the position of the latter with relation to the lens D.
Fig. 3 is a longitudinal section of photographic apparatus embodying my
invention.
TT is a long tube carrying an objective G of long focus, termed telescope
objective; an objective D D' composed of two achromatic lenses, viz. a converging
lens D, and a diverging lens D₁; and an enlarging searching device E composed
of two achromatic lenses of very short focus. This device E is mounted on a

page_text: movable tube provided with a rack that is actuated by means of a pinion on
a pin P.
The various lenses are so curved or shaped as to focus the chemical rays as well
understood. Fixed to the tube T T is a camera arranged to draw out in the
ordinary manner and furnished with an instantaneous shutter.
The entire apparatus is mounted on a pivotted stand having a double motion so
as to allow of any inclination in the vertical plane and in the horizontal plane.
On the apparatus is arranged a small sighting telescope or view finder L L the
optical axis of which is adjusted by means of screws so as to be parallel to the
optical axis of the photographic telescope. The eye piece of the view finder
carries a small prism of 45° which allows of observations being made in a direction
perpendicular to the axis of the apparatus and which re-erects the images; con-
sequently the objects are seen in the view finder in the positions they occupy on the
focussing screen.
The apparatus may be variously modified to suit the conditions under which it
is to be used without departing from the essential features of my invention.
Dated this 6th day of February 1892.
A. DUBOSCQ,
By L. W., per F. B.
COMPLETE SPECIFICATION.
Improvements in Photographic Apparatus.
I. ALBERT DUBOSCQ of 55 Rue St. Jacques, Paris, France, 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 improvements in photographic apparatus, and consists
in applying to a photographic camera, an optical apparatus constituting a
telescope.
This optical apparatus (hereinafter referred to as a telescope) allows of a direct
photographic reproduction of the image of objects situated at a considerable
distance, being obtained of such a size as to render the operation known as enlarging
unnecessary. The photographic apparatus may be used for photographing terrestrial
objects at great distances, and also celestial bodies, and may advantageously be
used for military and naval purposes.
Referring to the accompanying drawings left with my Provisional Specification
Figs. 1 and 2 are diagrammatic views illustrating the principle upon which my
invention is based.
Suppose the object A. B to be photographed, to be situated at a very great
distance from an achromatic lens G of great focal length and forming the object
glass of a telescope; then there will be formed at ab a very small and very brilliant
inverted image of the object A B. Now if an achromatic lens D of very short
focal length be located in such a manner that the image at ab shall be situated in
front of its principal focus, then there will be formed on the focussing screen of a
camera, an enlarged inverted image A' B' of the image at a b. This image A' B₁
will always be sharp, provided the focussing screen be situated beyond the point of
intersection of the rays from the lens D, whatever may be the distance between the
focussing screen and the lens D, and the greater the distance between the focussing
screen and the said lens, the larger will be the image A¹ B'. It will be seen that
the image A¹ B' of a i formed on the focussing screen will be reversed, consequently
the object A B will be seen in its natural position.
An important feature of this invention is the addition of a third lens E (Fig. 2)
which may be termed a search, field or enlarging lens and which has a very short
focal length. This lens E is located between the image at a band the lens D, the
focal length of which it shortens, and consequently increases its enlarging power.
The lens E receives the rays coming from the objective G, and causes them all to

page_text: pass into the lens D, thereby increasing the light and the extent of the field. By
suitable shifting the lens E, it may be made to serve for focussing on the focussing
screen without altering the position of the latter with relation to the lens D.
Fig. 3 is a longitudinal section of photographic apparatus embodying my
invention.
T, T is a long tube carrying an objective G of great focal length an objective D D'
composed of two achromatic lenses, viz. a converging lens D, and a diverging.
lens D'; and an enlarging searching device E composed of two achromatic lenses
of very short focal length. This device E is mounted on a movable tube provided
with a rack that is actuated by means of a pinion on a pin P.
The various lenses are so curved or shaped as to focus the chemical rays as well
understood. Fixed to the tube T T is a camera arranged to draw out in the
ordinary manner and furnished with an instantaneous shutter.
The entire apparatus is mounted on a pivoted stand having a double motion so as
to allow of any inclination both in a vertical plane and in a horizontal plane.
On the apparatus is arranged a small sighting telescope or view finder L L, the
optical axis of which is adjusted by means of screws so as to be parallel to the
optical axis of the photographic telescope. The eye piece of the view finder carries
a small prism of 45° which allows of observations being made in a direction
perpendicular to the axis of the apparatus and which re-erects the images; con-
sequently the objects are seen in the view finder in the position they occupy on the
focussing screen.
The apparatus may be variously modified to suit the conditions under which it is
to be used without departing from the essential features of invention.
my
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
1. Photographic apparatus constructed with a telescope having an object glass of
great focal length and such as to enable a lens of short focal length to throw upon
the focussing screen of a camera, a greatly enlarged photographic image of objects
situated at a great distance from the apparatus substantially as described and
shewn.
2. Photographic apparatus constructed and arranged as hereinbefore described
with reference to and shewn in the drawings.
D: 9.1 1. of Mauch 1800
ALBERT DUBOSCQ,
By L. W., per F. B.