Improvements in Photographic Cameras.
Year: 1898

page_text: Date of Application, 21st Nov., 1898-Accepted, 22nd July, 1899
Improvements in Photographic Cameras.
A communication from abroad by JEAN GUIDO SIEGRIST, called Guido Sigriste,
of 19, Rue Cambon, Paris, in the Republic of France, Artist Painter.
I, JOHN CORRY FELL, of the Firm of Fell and James, of 1, Queen Victoria
Street, in the City of London, Chartered Patent Agents, 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:-
My invention consists in a dark photographic chamber made by means of a
non-actinic envelope adapted to allow the actinic rays from the lens to pass by
means of a movable slit orifice, which can be operated by any convenient means
extremely close to the sensitive surface and parallel to the same without in any
way injuring it.
This parallel movement can be effected in a variety of ways.
The method I
have indicated in the accompanying drawing for moving the slit device is based
on the transmission of the motion of a grooved pulley R by means of a cord or
thread attached thereto and passing round a small guide pulley so situated as to
lead the cord to the slit device, which latter is guided in its movement of alterna-
tive disposition by any convenient means, so as to maintain its parallelism with
the sensitive surface.
I obtain thus a great speed of exposure.
The plate or sensitive surface A being in practice always at the same distance
from the back part of the lens B of the camera, it follows there is the necessity of
having the special non-actinic envelope hereinafter described in order not to
interfere with the parallel movement of the slit device to the plate, and to shield
the plate from light other than passes through the slit.
The essential features of the slit-device are as follows:-
The accompanying drawing represents a dark chamber in vertical section,
representing the slit device in front of and against the middle of the sensible
surface.
My non-acetinic envelope is formed of a quadrilateral or any other geometrical
form and is fixed at C to the interior of the side or end carrying the objective B,
the axis of which coincides with the centre of the quadrilateral figure. The other
extremity of my envelope is fixed to the slit device at D).
I have thus an envelope fixed by one of its ends and adapted at its other end
to be moved to a fixed distance in a plane parallel to the plates. This effect is
produced with my non-rigid envelope by reason of it being made with de-
formable, extensible and contractibie walls, these deformations, extensions or
contractions being brought about by the slit-device in its displacement. In a
word, my envelope to respond to the definition hereinabove described will be a
photographic bellows of which the forms and dimensions will be determined by
the forms and dimensions of the boxes, of the lens, and of the slit-device, on which
it is fixed by its two extremities.
In the middle position represented by the drawing, the side parts E E' of my
non-actinic envelope will be of equal length.

page_text: The slit device in descending will contract or fold on itself at the. part El
and simultaneously develop or elongate the part E. The inverse effect is produced
when the slit device reascends. Nevertheless one can insert in the middle of this
envelope a rigid partition more or less extended, the importance being that the
qualities of non-rigidity of extensibility and, of contractibility, in a word, of
deformation, is obtained at the two extremities fixed against the lens and the
slit device.
The pulley wheel R is operated by means of a spring barrel S or other equivalent
means. The slit device is pulled down to the bottom of the camera by any
suitable means such as a cord attached thereto and is retained in the set position by
a detent or stop. When the exposure is to be made the detent is released and
the spring barrel draws the slit device up. across the plate or other sensitive
surface by means of the cord. ·
11.
T
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
L..
In a photographic camera, a flexible non-actinic envelope in combination with
a traversing slit orifice for covering and exposing the sensitive plates or surfaces,
substantially as described and illustrated. in the accompanying drawings.
Dated this 21st day of November 1898.
FELL & JAMES,.
Agents for the Applicant.