Improvements relating to Photographic Cameras and Lenses.
Year: 1889

page_text: Date of Application, 18th Apr., 1889
Complete Specification Left, 18th Jan., 1890-Accepted, 22nd Feb.,. 1890
PROVISIONAL SPECIFICATION.
Improvements relating to Photographic Cameras and Lenses.
We THOMAS RUDOLPH DALLMEYER of 25 Newman Street, Oxford Street in the
county of Middlesex, Optician, and FRANCIS BEAUCHAMP of Hope College, Whalebone
Lane, Chadwell Heath in the County of Essex, Engineer do hereby declare the nature
of this invention to be as follows:-
Our invention relates to photographic cameras and lenses.
Heretofore in applying a lens to a camera for which it has not been specially fitted
it has frequently happened that the diaphragm slot does not occupy its proper position
owing to the fact that the lens when screwed up has not been turned quite far enough
or has been turned too far, and in order to remedy this defect it has been necessary
to alter the lens mount to adapt it for the camera. The same difficulty has also existed
when applying a shutter to a lens.
The object of our invention is to provide means whereby a lens or shutter can
always be caused to assume its proper position without the necessity for special
adjustment and to this end it comprises the improvements hereinafter described.
According to our invention the flange on the camera into which the lens is screwed
is provided with an adjustable ring or collar having a slight longitudinal movement
upon the said flange so that it can be adjusted to the proper position to cause the
diaphragm slot of the lens to occupy its proper position when screwed up.
In practice I prefer to adjust the ring or collar upon the exterior of the flange by
means of screw threads but it may be provided with a series of inclined teeth or
arranged in any other suitable manner.
In cases where a shutter is to be screwed into the front cell of a lens, the latter can
be provided with a ring or collar of similar construction.
Dated the 18th day of Anvil 1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements relating to Photographic Cameras and Lenses.
We, THOMAS RUDOLPH DALLMEYER, of 25, Newman Street, Oxford Street, in the
County of Middlesex, Optician, and FRANCIS BEAUCHAMP, of Hope Cottage, Whale-
bone Lane, Chadwell Heath, in the County of Essex, Engineer, 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:-
Our invention relates to photographic cameras and lenses.
Heretofore in applying a lens to a camera for which it has not been. specially fitted
it has frequently happened that the diaphragm slot does not occupy its proper
position owing to the fact that the lens when screwed up has not been turned
quite far enough or has been turned too far and in order to remedy this defect it
has been necessary to alter the lens mount to adapt it for the camera.
The same
difficulty has also existed when applying a shutter to a lens.
The object of our invention is to provide means whereby a lens or shutter can
always be caused to assume its proper position without the necessity for special
adjustment and to this end it comprises the improvements hereafter described.
According to our invention the flange on the camera into which the lens is screwed
is provided with an adjustable ring or collar having a slight longitudinal movement
FU671

page_text: :
upon the said flange so that it can be adjusted to the proper position to cause the
diaphragm slot of the lens to occupy its proper position when screwed up.
In practice we prefer to adjust the ring or collar upon the exterior of the flange by
means of screw threads but it may be provided with a series of inclined teeth or
arranged in any other suitable manner.
In cases where a shutter is to be screwed into the front cell of a lens, a ring or
collar of similar construction to that herein before described can be provided.
To enable our invention to be fully understood we will describe the same with
reference to the accompanying drawing which represents in longitudinal section so
much of a camera, lens and shutter as is necessary to illustrate our invention.
a is the camera front, the flange secured thereto and internally screw threaded,
and c the lens screwed into the said flange and having the slot d to receive the
diaphragms.
e is our adjustable ring which, as shown, is internally screw threaded and adapted
to fit into corresponding screw threads formed on the exterior of the flange b. The
said ring e is provided with an internally projecting flange f forming a face against
It is obvious the
which a flange or collar g on the lens bears when screwed up.
position of the ring e upon the flange b can be so adjusted that when the lens is
screwed home the diaphragm slot will be in a vertical position.
h is an instantaneous shutter of the kind described in the Specification of former
Letters Patent granted to us dated the 12th of October A.D. 1887 No. 13844
which shutter is attached to the lens by means of the tubular portion which is screw
threaded and screwed into the front cell of the lens.
is a ring which is screwed onto the said tubular portion i and which can he
adjusted thereon so as to hold the shutter in the required position. This ring is
thickened at the edge as shown and milled so that it can be readily turned.
We wish it understood that we do not limit this part of our invention to use in
combination with a shutter of the kind hereinbefore described as it is obvious that it
may be applied to other forms of shutter. Also in some cases the adjustable rings
may be fitted upon screw threads on the exterior of the lens tube instead of in the
manner hereinbefore described.
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:-
(1.) The combination with a photographic camera or lens of an adjustable ring
substantially in the manner, and for the purpose, set forth.
(2.) A photographic camera the lens carrying flange of which is provided
with an adjustable ring, substantially as described and illustrated in the accom-
panying drawing.
(3.) A lens having an adjustable ring or rings thereon substantially as described
with reference to the accompanying drawing for the purpose specified.
Dated the 18th day of January 1890.
Dated the 18th day of January 1890.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.