Improvements in Photographic Apparatus.
Year: 1892

page_text: Date of Application, 19th May, 1892
Complete Specification Left, 20th Feb., 1893-Accepted, 25th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in Photographic Apparatus.
JAMES DOUGLAS LYSAGHT 7 Crescent, Queenstown co. Cork, Ireland Major
Army Pay Department, do hereby declare the nature of this invention to be as
follows:-
My invention applies more particularly to that class of photographic apparatus,
known as hand cameras.
It provides a means for accurately focussing the image previous to exposure.
To accomplish this, I provide a plane mirror preferably silvered on its upper
surface to reflect the image projected by the lens on a piece of ground glass
inserted in the top of the camera. This mirror is attached to a plate which slides
in grooves on a frame in the same manner as the sliding stage of a microscope
being actuated by a rack and pinion. The frame is so constructed that it forms an
angle of 45° with the ground glass screen.
To obtain a suitable chamber or hood to enclose the ground glass screen I
provide two flaps or doors hinged to the top of the camera-one of these doors is
fitted with side wings-when in use for focussing these doors or flaps are raised by
rods to be hereafter described and form a focussing chamber the width of aperture
of which is capable of adjustment.
To enable the operation of focussing to be effected in the most satisfactory
manner, I provide means, to be hereafter described, to open the stop or diaphragm
of the lens to its fullest extent at the same time that the doors of the focussing
chamber and mirror are raised.
At
To accomplish these combined movements I connect the pinion that actuates the
mirror by means of a train of wheels to a vertical slide furnished with a rack.
the upper end of this slide suitable rods are fitted connected with the flaps of the
focussing chamber.
A lever handle outside the camera connected with a toothed wheel inside in
gearing with the train of wheels above mentioned actuates the apparatus.
The stop or diaphragm of the lens is moved as follows:-1 attach a roller to
the shaft carrying the wheel and lever handle, to this roller one end of a cord or
chain is attached, the other end being secured to the knob or projection from the
stop this stop or diaphragm being preferably that known as the iris.
A spiral
or other spring fixed between the side of the camera and the knob of the stop
serves to bring it back to any required position. An adjustable pin or screw
permits of any degree of adjustment of size of aperture.
For use with my invention I prefer that form of exposing shutter known as the
roller blind, fitted as close as possible to the sensitive plate or film.
The claims are:-That one movement of the lever handle in one direction raises
the mirror and the doors of the focussing chamber at the same time opening the
stop of the lens to its full aperture, thus enabling an accurate focus to be obtained,
by means of the usual rack and pinion attached to the lens or camera, and a
reversal of the handle lowers the mirror closes the doors of the focussing chamber
and returns the stop of the lens to any prearranged position.
Dated this Nineteenth day of May 1892.
J. D. LYSAGHT, Major,
Army Pay Department.

page_text: COMPLETE SPECIFICATION.
Improvements in Photographio Apparatus.
I, JAMES DOUGLAS LYSAGHT of 7 The Crescent, Queenstown, County Cork,
Ireland, Major in the Army Pay Department, 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 photographic cameras and more particularly to that
class of cameras known as "hand-cameras" (though I by no means limit myself to
the latter) and has for its object to enable very effective and accurate focussing by
means which can be readily and quickly operated to effect this purpose, viz. :-
(1) A large focussing plate or surface upon which the image object or picture
(to be photographed) is depicted through the actual lens (by reflection from a
mirror) used in taking the photograph.
(2) A mirror or reflector capable of sliding or moving (inside the camera)
across the path of the lens aperture at an angle of 45 degrees (or thereabouts) so
as to intercept and throw the picture etc. upon the focussing plate or surface-as is
well understood.
(3) Means to automatically lock the closed shutter during the focussing.
(4) A hood screen or enclosing device to surround and cover in (so as to darken)
the focussing plate or surface capable of folding or closing up snugly in or against
the camera case and means to unfold or raise such hood etc. for focussing and to
close and fold same snugly in or against the camera case when not focussing.
(5) An iris diaphragm or "stop" which can be set (as is well understood) to
any degree of aperture and means or apparatus to connect same to some working
part of the mechanism operating the mirror or the hood (or both) so that when the
inirror is moved into position to reflect the image etc. on to the focussing screen (or
when the hood is raised) this movement will simultaneously open to its full extent
the iris diaphragm and so clearly depict such image etc. on the focussing screen-
while on the other hand when the hood is closed or the mirror moved away out of
the path of the lens then this same movement will release the iris diaphragm so
that same is returned by a spring (or otherwise automatically returns) to its set
position so as to close the diaphragm to the size of aperture to which it may be set
ready for giving the photographic exposure.
And in order that my said present invention may be easily understood and readily
carried into practice I will proceed to fully describe same with reference to the
drawings hereunto annexed :—
Sheet 1 illustrates a camera (in sectional side elevation) having my improvements
applied thereto according to my present invention.
Sheet 2 (Figs. to 6) illustrates my present invention carried out by slightly
modified mechanical details.
Referring to Fig. 1 Sheet 1 :-
A is the main driving axis-upon which a suitable crank arm and handle are
mounted outside the camera case.
B is a toothed wheel on axis A.
C is a small pinion gearing with B.
D is axis on which pinion C is fixed.
E is rack fixed or connected to the mirror moving or sliding in the fixed
frame F.
Fis the frame or guide fixed at an angle of about 45 degrees under the
focussing screen Z in or on which the mirror or reflector is moved up and down'
by pinion C gearing with the rack E.
G is large toothed wheel gearing with C and also gearing with small toothed
wheel H

page_text: The operation is as follows :-
To close the camera ready for taking a photograph-the axis A is rotated by
means of a crank arm or lever such as X (in the opposite direction to the arrow
thereon) and thereby the toothed wheel B rotates pinion C and draws down
the rack E and the mirror out of the path of the lens U and simultaneously the
toothed wheel G rotates H which latter draws down the rack I and with it the
rod J which pulls down the lever arms K and L respectively and thereby the two
flaps M and N are drawn down (the flap P-when used-doubling back on N)
and the flap N lies under M parallel (or thereabouts) with Z so that M and N lie
snugly and closely together in a horizontal direction over Z and the camera case W
is thereby made completely light-tight and ready to give an exposure.
This same action has also simultaneously released the cord or connection Q
whereby the iris diaphragm is released so that same is closed to the size of
aperture for which it has been set.
To prepare the camera ready for focussing-by moving the handle or arm X
in the direction indicated by the aforesaid arrow the opposite movement of all these
parts takes place to that just described.
A locking mechanism (such as that shown on Sheet 2-not shown on Sheet 1)
in connection with the handle X may advantageously be used to lock the roller
blind or other shutter so that same cannot be opened during focussing.
Referring now to Sheet 2 of the drawings:
Fig. 2 is a side elevation of a camera having my improvements applied thereto
in a modified form.
Fig. 3 is an end view of the camera looking at the front of the lens and
Fig. 4 is a view of the opposite end of the camera-with the back thereof
removed.
Fig. 5 is a sectional side elevation of one side of the camera.
Fig. 6 is a similar view of the opposite side of the camera.

page_text: o is small Loothed wheel or pinion on axis a.
c is toothed wheel or segment actuated by b and fixed on axis d.
(Fig. 6) is slotted lever arm fixed on d also.
fis frame or guide for sliding mirror or reflector.
9 is pin or stud on or in connection with the sliding mirror which pin g moves
in the slot in levere and thereby moves the mirror up and down-instead of the
rack and pinion arrangement as in Fig. 1.
his link or connecting rod pivotted at its lower end to levere and at its upper
end to lever i turning on a pin or stud j.
i is a pivotted lever actuated by hand at its free end connected to lever k which
raises and lowers flap M.
K L M N O and P are all substantially the same parts as described with
reference to Fig. 1-the only difference being that whereas (in Fig. 1) the
levers K and L were both actuated and situated on one side of the camera now in
this case (Sheet 2) the link actuates K and the flap M only at one side of the
camera and the other flap N is actuated from the other side of the camera, as
follows:-
The axis or axle d Fig. 6 extends right across the width of the camera (nearly)
and at its other end Fig. 5 has fixed thereon a second slotted link e* which
operates a second pin g* on the mirror or in connection therewith.
k link to actuate L and flap N.
I is intermediate double jointed link for this purpose.
an
m (Fig. 6) is a link or rod pivotted to the crank arm n fixed on the axis a.
o is a horizontal rod pivotted to m at one end and at its other moves
inclined piece thereon or otherwise acts in such a manner that when it moves it
pushes out of its path a pivotted arm p connected to the iris diaphragm or stop.
p is an arm or lever turning on the fixed centre q.
ris a spring (Fig. 3) which normally keeps the arm p pressed outward away
from the lens.
is a set screw by which the size of the aperture is regulated or set.
STUV and W all refer to the same parts respectively as hereinbefore
described with reference to Fig. 1.
t is a swelling or shoulder on the arm a to lock the shutter so as to prevent
same accidentally giving an exposure during focussing.
u is a pawl or finger which is normally kept pressed, over the releasing catch v
of the shutter-but when the lever arm a with shoulder t is moved right back
after focussing when ready to give an exposure this shoulder t will throw the
pawl u clear of the stud or catch v and the shutter can now safely be released.
The operation is substantially the same as before described :-To focus-the
lever arm & Fig. 2 is moved down in the direction of the arrow (Fig. 2) and by
the aforesaid mechanism the two slotted levers e ex are thrown up and thereby
move upwards the mirror and also simultaneously raise the flaps M and N forming
the hood and also at same time the rod o is moved so as to press in the lever arm p
and thereby overcome the spring r and so open the iris diaphragm to its widest
extent and similarly all the parts can be simultaneously closed or moved back by
the single operation of turning the lever arm x in the other direction.
I find it a great advantage to use a reflector or mirror coated or otherwise
prepared by having the front surface coated on the face thereof with any suitable
reflecting material-as by this means I find I get a truer image depicted on the
focussing screen.
Finally I would remark that I do not wish to confine myself to the point from
which I operate all the parts simultaneously as herein before described as for instance
the crank handle X or z may be placed directly onto the axis on which the flap M
turns and is hinged to the camera case and thus operate all the parts by similar
mechanism to that hereinbefore described the axis of the hinge of M being thus
the main driving axis or again I might dispense with such actuating handle X or

page_text: and by placing a knob or other projection or device towards the free edge of M
then this flap M would become the actuating lever itself.
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 I
claim is :-
1. In hand cameras or other photographic cameras to which my invention may
be applicable the arrangement and combination of a hood or enclosing shield
which when lowered or folded in its closed position forms a light-tight cover over
a focussing screen and which is capable of being raised or unfolded to form a hood
or shield to darken said screen during focussing, means to open and close i.e. to
operate such hood with a connection between such hood operating device and an
iris diaphragm or stop in the lens so that the movement of the hood operating
mechanism to open the hood will simultaneously fully open the iris diaphragm or stop
and also the movement to close or fold the hood will simultaneously close or permit
the closure of the said diaphragm to any degree of aperture to which it may be set
substantially in the manner and for the purposes hereinbefore described.
2. In photographic cameras of the character hereinbefore described-the inven-
tion set forth in above Claim 1 in combination and acting in conjunction with a
mirror or reflector arranged and mounted to travel in a diagonal plane beneath the
focussing screen i.e. at an angle of 45 degrees thereto this mirror being caused to
travel by being suitably connected to some working part of the mechanism
operating the hood and diaphragm as herein before set forth so that the act of
opening the said hood will thereby simultaneously move the mirror into position
opposite the lens to reflect the image etc. coming therethrough onto the focussing
screen and similarly the act of closing the hood will move the reflector out of the
path of the lens substantially in the manner and for the purposes hereinbefore
described.
3. In apparatus of the character described-1 claim the combination and arrange-
ment of a mirror or reflector to be mechanically caused to move into and out of
position under the focussing screen at an angle of 45 degrees thereto the mechanism
effecting this movement being connected or having a connection with the iris
diaphragm or stop in the lens so that the operation of moving the said mirror into
the path of the lens will thereby simultaneously open fully the iris diaphragm and
similarly the withdrawal of the mirror out of the path of the lens will thereby
simultaneously close or permit the closure of the said diaphragm to any degree of
aperture to which it may be set substantially in the manner and for the purposes
hereinbefore set forth.
501
7
Ր
1
1000
TONGUE & BIRKBECK,
34, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.