Improvements relating to Screens used in Producing in Cameras Photographic Negatives suitable for Mechanical Printing Processes.
Year: 1889

page_text: Date of Application, 26th Apr., 1889
Complete Specification Left, 27th Jan., 1890-Accepted, 15th Mar., 1890
.PROVISIONAL SPECIFICATION.
Improvements relating to Screens used in Producing in Cameras
Photographic Negatives suitable for Mechanical Printing Processes.
We CHARLES STUDDERS and GEORG KOHL of the firm of Studders & Kohl of
Leipzig Reudnitz in the Empire of Germany do hereby declare the nature of this
invention to be as follows:
.
This invention relates to the production in a camera of photographic negatives
suitable for mechanical printing processes and especially to the process in which said
negatives are produced by arranging before the sensitive plate a transparent screen
having a number of opaque parallel lines or cross hatchings. Heretofore it has been'
usual to place the screen and plate in the dark back and expose the same in the
camera for a certain period and then to remove the dark back and replace the screen
by another screen, the lines of which stand generally at an angle of 90° to those of
the first screen and again expose the plate in the camera for the remainder of the
necessary period of exposure. This twofold insertion of screens occupies more time
and trouble and the-sensitive plate is liable to be shifted in the process so that the
negative is doubled and therefore useless.
The object of this invention is to enable one screen to be used and to be moved
into the second position without removal from the camera.
To this end I support the said screen in a circular frame providing the latter with
a fixed bead and with a movable bead adjusted by set screws for holding the screen..
This circular frame is supported in a circular hole in a suitable carrier adapted to be
placed in the camera so that the frame may be moved for an angle of 90° degrees (or
for a greater or less anglo if desired) in its plane. Suitable stops are provided for
accurately limiting this movement which may be effected by hand by means of a cord
connected to the frame and led out through a suitable hole in the camera.
The screen
being set in one position and the sensitive plate inserted, the lens is uncovered a
half time exposure given and the lens is again covered. The screen is then
revolved by the cord into the second position and the remainder of the exposure
given.
D
ac
1
C A 1000
HERBERT & Co.,
Agents to Applicants.
COMPLETE SPECIFICATION.
Improvements relating to Screens used in Producing in Cameras
Photographic Negatives suitable for Mechanical Printing Processes.
WA CHARLES STUDDERS and GEORG ĶOHL Manufacturers both of Leipzig-Reudnitz
in the Empire of Germany 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 the production in a camera of photographic negatives
suitable for mechanical printing processes and especially to the process in which said
negatives are produced by arranging before the sensitive plate a transparent screen
having a number of opaque parallel lines or cross batchings. Heretofore it has been
usual to place this screen and plate in the dark back and expose the same in the
camera for a certain period and then to remove the dark back and replace the screen
by another screen, the lines of which stand generally at an angle of 90 degrees to those
of the first screen, and again expose the plate in the camera for the remainder of the
necessary period of exposure.

page_text: This two fold insertion of screens occupies more time and trouble and the sensitive
plate is liable to be shifted in the process so that the negative is doubled and therefore
useless.
The object of this invention is to enable one screen to be used and to be moved
into the second position without removal from the camera. To this end I support the
said screen in a circular frame providing the latter with a fixed bead and with a
movable bead adjusted by set screws for holding the screen. This circular frame is
supported in a circular hole in a suitable carrier adapted to be placed in the camera
so that the frame may be moved for an angle of 90 degrees (or for a greater or less
angle if desired) in its plane.. Suitable stops are provided for accurately limiting this
movement which may be effected by hand by means of a cord connected to the frame
and led out through a suitable hole in the camera. The screen being set in one
position and the sensitive plate inserted the lens is uncovered, a half time exposure
given and the lens is again covered. The screen is then revolved by the cord into
the second position and the remainder of the exposure given.
In the accompanying drawings which illustrate the method of carrying this inven-
tion into practice, Fig. 1 is a front elevation of the parts showing the screen in its first
position. Fig. 2 is an elevation showing the screen in its second position. Fig. 3
is a cross-section and Fig. 4 a part cross section on a larger scale.
A is the screen, D the circular frame having the fixed bead H and the movable
bead G the latter to be fixed by set screws as shown. The frame D is held in the
circular track of the frame C by the tongues E. N and O are two stops to limit the
travel of the pin P which is fixed on the frame D and consequently to limit
the rotary movement of said frame. K is the cord attached to pin L and passing
through hole M for revolving the frame D. The spring F serves to steady the
frame D.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
For the preparation of negatives or photographs for photo mechanical printing
.1. The combination of a cross hatched plate A with means for holding same in the
camera and rotating same without removal of the photographic plate substantially as
set forth..
2. The construction consisting of circular frame D with beads G and H for holding
said plate A, frame or holder C, stops for limiting the rotary movement of said
frame D and a cord or equivalent K for rotating said frame D substantially as and
for the purpose set forth.
Dated this 25th ...
1000
HERBERT & Co.,
18, Buckingham Street, Strand, W.C., Agents to Applicants.