Improvements in Effecting Photographic Exposures.
Year: 1894

page_text: Date of Application, 12th Sept., 1894
Complete Specification Left, 10th July, 1895-Accepted, 10th Aug., 1895
I NOVISIONAL SIEVITICATION.
. Improvements in Effecting Photographic Exposures.
I CHARLES DAY DURNFORD of Elmhurst Shooter's Hill in the County of
Kent Lieutenant-Colonel and Assistant Commissary-General of Ordnance Retired
do hereby declare the nature of this invention to be as follows:-
The object of my invention is to provide means and appliances and a cycle of
operations whereby photographic exposures or that is to say the exposure of
sensitive plates or surfaces in a photographic camera. shall be effected and
arranged and regulated so far as may be convenient or desirable in like manner
as is naturally done in analogous cases by the eye or in other words to cause these
mechanical exposures to be performed so far as may be expedient or preferable in
the same or in a similar or like manner as a view is naturally or by the natural
process presented to the eye whereby improved results will be produced many
difficulties will be overcome and various evils will be greatly even if not entirely
obviated.
To carry out this object say for example in and with any ordinary double
combination view lens in front of or before the same I mount on the lens tube in.
any suitable framing or otherwise a screen or flap which may be hinged to such
framing along its upper edge or may be capable of sliding vertically across the
lens tube and the line of the same or may be otherwise fitted in any usual and
suitable manner.
Between the two parts of the lens I mount or fit in any ordinary
manner a diaphragm of any customary and suitable kind which may be capable
of sliding vertically across the lens tube and in this diaphragm is an aperture the
lower part whereof is large being of any appropriate size to admit as much
light as is possible or may be necessary or desirable while the upper part
thereof is gradually or otherwise decreased until the extreme upper end of this
aperture may be only quite a small slit or slot. The screen or flap and the
diaphragm are connected together in any ordinary and convenient manner it
may be by a cord passing over a pulley on the top of the framing or by a lever
or levers or by an arm or arms or by a wheel or wheels or, otherwise in such wise
that while and as the screen or flap is being elevated the diaphragm is being
lowered and vice versa.
Therefore when and as the screen or flap is raised light can first enter through
the lower part of the aperture of the lens tube thereby uncovered and passes
through the large lower part of the aperture in the diaphragm directly to the upper
part of the sensitive surface in the camera and as the screen or flap is further raised
and the diaphragm is further lowered so the light passes through the diminishing
or diminished aperture in such diaphragın until when the screen or flap has reached
its uppermost position or thereabouts and the diaphragm has been correspondingly
lowered the light can only pass through the small upper end of the aperture in
such diaphragm directly to the lower part of the sensitive surface in the camera
until the exposure, is finished.
Another similar screen or flap could when desired be similarly but invertedly
mounted on the lens tube the upper edge whereof could at the desired distance
follow upwards the lower edge of the aforesaid screen or flap, being similarly
operated thereby or by the diaphragm.

page_text: It is very convenient also to attach to the edge of the screen or flap a fringe of
any suitable material to break up and prevent the formation of any solid and
continuous edge to the light that passes under or over this edge as the screen
or flap is raised.
It is very evident therefore that in and by and during the aforesaid cycle of
operations the various parts of this apparatus are capable of imitating and do
imitate to a very large extent the functions of the upper and lower eyelids the
eye lashes thereon and the iris the pupil and the lens of the eye so far as may
be needful or desirable.
I would further point out that by means of the decreasing or decreased area
of the aperture in the diaphragm that is in operation as such diaphragm descends
the practical and photographie proper focussing of even the most distant objects
in the view will be effected although the primary focussing was only effected in
relation to the foreground but this effect can if preferred be enhanced by connecting
with this apparatus by any usual and suitable means or devices the screw or other
operative focussing appliance of the lens in such wise that it can be properly
operated by the movement of such apparatus for the purpose of properly
adjusting the focus upon the arranged for distance during the exposure thereon.
The screen or flap can be made and formed and fitted in any customary and
convenient manner in such wise that it can perform its necessary functions of
uncovering first the lower part of the aperture of the lens tube and of moving at
the proper time with the diaphragm.
For example the screen could be formed as an hood the frames or ribs whereof
would be pivoted on each side of the lens tube either on such lens tube or perhaps
preferably on a framing mounted thereon or therearound and this hood could open
in the same manner upwardly uncovering first the lower part of the aperture of
the lens tube being followed upwards when so arranged by the upper edge of
another similar but inverted hood as is before described and it will perhaps
generally be preferable to operate this hood or these hoods by levers or arms from
the diaphragm.
Again the flap could be formed of two plates which would be pivoted together
or otherwise above the lens tube and could move on such pivot or pivots trans-
versely to the line of this lens tube in such wise that their lower parts would first
separate uncovering first the lower part of the aperture of the lens tube and
these plates would similarly be operated from and by the diaphragm.
The diaphragm also can be any suitable and ordinary photographic stop
diaphragm shutter or other arrangement which can slide or revolve or be otherwise
actuated and can communicate its movement to the screen or flap and has an
aperture so formed and arranged as likewise to perform its necessary function of
admitting to the upper part of the sensitive surface in the camera most light at
the commencement of the exposure and gradually or otherwise decreasing the
amount of such light so admitted until at the end of such exposure only a very
little light can pass through this aperture to the lower part of the sensitive surface
in the camera.
The diaphragm also is preferably so formed and constructed as to act likewise
as a shutter in completely closing the aperture of the lens tube before and after
the desired exposure the which it can properly do by its vertically sliding movement
when so arranged before the screen or flap is raised and after the same has been
raised to its uppermost position but the screen or flap itself or any other ordinary
and suitable appliance may also be fitted and used to act as a shutter in this sense
as may be desired in each particular case.
This apparatus may be operated in and by any ordinary appliances and may be
caused to work at any desired speed which speed may be alterable and
any suitable
stop or other device may be provided to retain the several necessary parts of the
apparatus in their last positions so long as may be desired before the exposure
is completed.
I have thus described this apparatus as arranged to admit the light through the

page_text: lower part of the aperture of the lens tube to the upper part of the sensitive
surface in the camera or that is to say to take the foreground first but it is obvious that
all this procedure and cycle of operations can when desired be reversed and the
sky or distant or more highly lighted objects be taken first by commencing the
exposure with the screen or flap raised to its uppermost position and the diaphragm
as nearly closed as is arranged for.
Instead also of placing the screen or flap in front of or before the lens and
therefore outside the camera as is aforesaid I may also place the same behind the
lens and inside the camera in which case it could be fitted and would operatè in
the same manner but must obviously be inverted to perform the aforesaid functions
in the same sequence.
When this apparatus is to be used with a single combination lens the diaphragm
is preferably of the "iris" type or of other such style that will close to and open
from the centre to prevent distortion and this diaphragm can be used with or
without another shutter as may be preferred while the screen or flap would
preferably be mounted on a tube or cap some little distance in front of the lens
although it may also be mounted in other suitable and ordinary position in respect
of the lens.
Dated this 12th day of September 1894.
HART & Co.,
186, Fleet Street, London, E.C., Agents.
1 CHARLES DAY DURNFORD of Elmhurst Shooter's Hill in the County of
Kent Lieutenant-Colonel and Assistant Commissary-General of Ordnance Retired
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 :-
The object of this my invention is to provide means and appliances and a cycle
of operations whereby photographic exposures or that is to say the exposure of
sensitive plates or surfaces in a photographic camera shall be effected and arranged
and regulated so far as may be convenient or desirable in like manner as is naturally
done in analogous cases by the eye or in other words to cause these mechanical
exposures to be performed so far as may be expedient or preferable in the same or
in a similar or like manner as a view is naturally or by the natural process
presented to the eye.
To carry out this object I admit the light rays to the sensitive surface in the
camera through an aperture that varies in size during the exposure and I also
shield the lens variably so that the light rays may at any particular time and from
time to time and at all times operate to the best effect and all parts of the sensitive
surface may receive the properly proportioned exposures whereby improved results
will be obtained many difficulties will be overcome and various evils will be greatly
even if not entirely obviated and I perform and effect this operation by causing a
diaphragm wherein is the aperture that varies in size during the exposure to move
in harmony with and the aperture to vary in size in harmony with a flap or hood
that shields the lens variably.
In order the more clearly to explain this my invention and in what manner the
same is to be performed I refer to the accompanying drawing wherein I have shewn
my invention as applied to and with an ordinary double combination lens.
Referring to Figures 1, 2, 3, 4 and 5 I can inount and place most conveniently
on the front of a lens tube A a framing B of any suitable style and shape but
preferably square or rectangular on the top edge of which is horizontally hinged a

page_text: flap C of any suitable opaque material that can properly cover the front of the lens
tube A and on which are preferably fitted or formed the wings or lateral flanges C
so as to reduce the amount of side light that can pass the flap C when and as it is
being raised or opened and any suitable devices such for example as a stud and slot
or recess can be provided to ensure that the framing B can and will always be
placed on the lens tube A in the exactly proper position or the framing B can when
desired be dispensed with and the flap C can be mounted an hinged in a similar
manner but directly on and to the lens tube A. Between the two parts of the lens I
fit and arrange a diaphragm D capable it may be of sliding vertically across the
lens tube A in suitable guides or grooves D' which diaphragm D admits the light
rays to the sensitive surface in the camera through a suitable aperture D' that can
and does vary in size during the exposure.
In Figure 91 shew one very convenient style of construction of this diaphragm D
for the aforesaid purpose according to which an aperture D' is made therein the
lower part of which is large being of any appropriate size and shape to admit as
much light as is possible or as may be necessary or desirable while the upper part
thereof is gradually or otherwise decreased until the upper end of this aperture D
may be only quite a small slit or slot preferably terminating in a small circular
enlargement.
In Figure 10 shew another very convenient style of construction of this
diaphragm D for the aforesaid purpose according to which the lower part of the
aperture D³ is so enlarged as to cut off all the lower part of the diaphragm D below
the same leaving only the upper and smaller part thereof in the diaphragm D to
perform its function.
In all cases any suitable notches or recesses or the like may be made in the side
edges of the diaphragm as is customary to allow any ordinary stop or catch or the
like to arrest the movement of such diaphragin in any desired position and at and
for any desired time.
The diaphragm D and the flap C are connected together in such wise that they
will move in harmony with each other and with the variation in size of the
aperture D in such diaphragm D during the exposure and I shew in the
accompanying drawing some very appropriate and convenient methods of and
apparatus for performing and effecting this operation but I would have it clearly
understood that I do in no wise limit myself thereto for any other method of and
apparatus for causing the diaphragm to move in harmony with and the aperture
in such diaphragm to vary in size in harmony with the flap may be used.
Figure 1 is a side elevation of one arrangement wherein a standard E is erected
on the framing B and on the top thereof is mounted a drum E' capable of revolution
wherearound or whereover passes and whereto may be attached a cord or chain or
the like E2 by which the flap C and the diaphragm D are adjustably and alterably
connected together in such wise that the descent of the diaphragm D and the ascent
of the flap Care synchronous and this action may be produced by the diaphragm D
being or being made heavier than the flap C or by a coiled spring applied to the
drum E or by other usual devices as also can the reverse action when such may be
desired. The drum E' may sometimes be mounted eccentrically on the standard E
so that the speed at which and the distance through which the flap C and the
diaphragm D respectively travel may be different for which purpose likewise the
drum E may consist of and be two drums of differing diameters whereto the flap C
and the diaphragm D would respectively be connected according as it may be
desired that the flap C or the diaphraġm D should move the faster or the
farther.
Figure 2 is a side elevation and Figure 3 is a front elevation of another arrange-
ment wherein also a standard E is erected on the framing B and on the' side of this
standard E is mounted a drum F capable of being partly rotated by an internal
coiled or other spring the tension whereof can most conveniently be alterable and
adjustable in any ordinary manner and an arm' F' secured on this drum F is connected
with the flap C by a rod F so that the partial rotation of the 'drum F opens' or

page_text: closes the flap C. On the top of the standard E is pivoted a vertically rocking
lever G which is parallel with the line of the lens tube A and to and by the one
end of this lever G is connected and suspended in any convenient and usual manner
the diaphragm D. On the other end of the lever C is pivoted an adjustable
arm H on the free end whereof is mounted a roller H' it may be of indiarubber or
other soft material wherewith the flap C can come in contact and to alter and
regulate the angle that this arm H makes with the lever G a worm screw rod G'is
mounted on such lever G which gears with and into corresponding teeth on the
boss H* of the arm H and the lever G is preferably so counterbalanced that
normally it retains the diaphragm D in its uppermost position as is shewn in these
figures. When the arm H is brought by the worm screw rod G¹ into the position
shewn by solid lines in Figure 2 it is obvious that directly the flap C commences to
rise the diaphragm D will be caused to descend but when this arm H is similarly
brought into the position shewn by dotted lines in Figure 2 the flap C will have
risen through a large arc before the diaphragm D is caused to descend and in like
manner when the arm H is in any other position there will be a corresponding
difference in the time the flap C and the diaphragm D commence their respective
movements.
Figures 4 and 5 are elevations on opposite sides of another arrangement wherein
also a standard E is erected on the framing B and on one side of this standard E is
pivoted a vertically rocking lever K which is parallel with the line of the lens tube A
and one end of this lever K is loosely connected with the diaphragm D in this
manner that is to say on the end of the lever K is pivoted a shoe or guide L wherein
can slide freely a bar or rod L' jointed to the top of the diaphragm D. On the
one side of the other end of the lever K is pivoted a quadrant M and a tail M¹ of
this quadrant M is connected with the flap C by a rod M2. On the same side of
the lever K is secured one end of a spring bar N a pin on the free end whereof can'
engage in one of a series of holes N made in the quadrant M near the periphery
thereof or in other manner the lever K and the quadrant M are so fitted that their
relative positions in respect of each other can be altered and adjusted. On the other
side of the standard E is pivoted near the top thereof an hanging bar P and a pin Pi
on the free and lower end thereof passes through a long slot E³ in the standard E
and engages between jaws K' formed therefor on the lever K and a spring rod P
is secured to the lower end of the bar P in such wise that when it is entered into a
notch E on one edge at the top of the standard E as is shewn in Figure 4 it will
plainly tend to move the lower end of the bar P to the right and through the pin P
will rock the lever K raising that end thereof on which is the quadrant M while
when this spring rod P is entered into a notch E' on the other edge at the top of
the standard E it would plainly tend to rock the lever K in the opposite direction.
In the former case the lever K is caused normally to remain in the position shewn
in these figures and the diaphragm D is not supported thereby but by a suitable
catch or stop or the like. When the quadrant M is in the position shewn in
Figure 4 and the flap C commences to rise the shoe L sliding on the bar L' will
soon arrive near the top of the diaphragm D when a flat spring or catch or hock or
the like L on such bar L' will so enter or engage such shoe L as to connect the
same with this bar L' in a sufficiently rigid and strong manner as to sustain the
weight of the diaphragm D and this shoe L or the head L* of its pivot will then
retire the catch or stop or the like and leave the diaphragm D free to descend with
the lever K. When on the other hand the quadrant M is in the position shewn in
Figure 5 the shoe L has farther to slide on the bar L' before it connects itself with
and releases the diaphragm D as is hereinbefore described and therefore the flap C
will have risen through a larger arc before the diaphragm D descends. In the
latter case that is to say when the spring rod P is entered into the notch E' the
rocking lever K will be caused normally to remain in the opposite position to that
shewn in these figures and the diaphragm D would be in its lowermost position
while the flap C would be fully open and the aforesaid cycle of operations would
be performed but in a reversed sequence."

page_text: I have heretofore described the flap as hinged and as opening by turning on
such hinges for as a general rule I consider that the best results are produced
by this arrangement but it is evident and I would have it clearly understood
that I do in no wise limit myself thereto for the flap can obviously perform the
same functions and produce the like effect by sliding vertically on or in the
framing and the same appliances that are herein before described could cause aud
govern this movement in the same manner.
Figures 6 and 8 are side elevations of an arrangement wherein an hood is used
instead of a flap and Figure 7 is a front elevation of the same with the hood
removed. The framing S that is mounted in this case on the front of the lens
tube A is preferably circular in shape and a semicircular rib or frame T is pivoted
on each side of this framing S and can surround the lower half thereof and to this
rib T and to the upper part of the framing S are tightly secured the edges of
the opaque but flexible material V that forms the hood which therefore when the
rib T is in the position shewn in Figures 6 and 7 properly covers the front of the
lens tube A. To raise this rib T one or both of the ends thereof may be prolonged
and any suitable appliances or devices may be arranged to act on such prolongation
or prolongations but I preferably connect a rod W to the crown or middle part of
the rib T and to this rod W I joint another rod W₁ the other end whereof is
pivoted on the framing S above the lens tube A which articulated rods W and W'
are inside or underneath the hood V. To the joint of these rods W and W can
be connected the cord or chain or the like E' herein before described in respect of
Figure 1 or the connecting rod F herein before described in respect of Figures 2
and 3 or any other usual appliance suitable for lifting this hood in manner as is
shewn in Figure 8 and connecting the same with the diaphragm and the action and
effect of the hood will plainly be the same as or similar to those of the flap
hereinbefore described.
When the desired cycle of operations is to commence with the flap or hood
tightly closed over the front of the lens tube the diaphragm as a general rule is
preferably so arranged in its uppermost position that when the flap or hood
commences to rise and admit the light rays through the lower part of the aperture
of the lens tube this diaphragm is giving or allowing the largest opening for these
light rays to pass to the upper part of the sensitive surface in the camera that is
desired and has been allowed for and as the flap or hood continues to rise so at the
predetermined time does the diaphragm descend and gradually or otherwise
decrease this opening until the light rays can only pass to the lower part of the
sensitive surface in the camera through the small upper end of the aperture in the
diaphragm in which position it may frequently be advantageous to arrest all
movement and especially that of the diaphragm for a certain time and then to
permit the operation to be completed and the diaphragm in its lowermost position
entirely closes the aperture of the lens tube by its upper part D³ shewn in
Figures 9 and 10 which acts as a shutter.
It may however oftentimes be advantageous to commence the cycle of operations
with the flap or hood partly open as is shewn by dotted lines in Figure 1 the
amount of which opening can be varied and adjusted having regard to the particular
view that is to be photographed or to the light or to other surrounding circum-
stances. In this case the diaphragm can be made as is shewn in Figure 9 and is
so arranged in its uppermost position that the lower part D thereof is acting as a
shutter and has entirely closed the aperture of the lens tube and when the flap or
hood commences to rise and open further the diaphragm descends and uncovers
first a small part of its aperture allowing the light rays to pass to the upper part
of the sensitive surface in the camera and as these movements proceed so this
opening that is given by the diaphragm gradually or otherwise increases and
attains its maximum and then is gradually or otherwise decreased and the operation
is completed in manner as is hereinbefore described. The diaphragm may likewise
be in this position and act in this manner when the cycle of operations is to
commence with the flap or hood tightly closed over the front of the lens tube and

page_text: in every case the aperture in such diaphragm may be made of any convenient
shape and may be arranged in any convenient manner and need not necessarily and.
always have its lowest part the largest as is bereinbefore described.
Whenever it may be expedient so to do an ordinary bellows or other regulator R
shewn in Figure 2 may be applied to the rocking lever or to other convenient part
of the apparatus to regulate and govern the speed at which the apparatus is to
work and at which the required movements are to be made.
It may sometimes be desirable to mount another flap on the lens tube or on the
framing thereon in a similar manner but invertedly the upper edge whereof could
at the desired distance follow upwards the lower edge of the aforesaid flap being.
connected therewith or operated thereby or by the diaphragm or otherwise.
In the same manner another hood could be fitted as is shewn in Figure 8 wherein
another similar rib X is complementarily pivoted on the framing S and a similar
opaque but flexible material Y is secured to this rib X and to the lower part of
the framing S and this rib X can be connected with the rib T by the band Z so.
that it will follow the same upwards with the desired interval or space between.
The several apparatus herein before described and all the various parts thereof
such for example as the flaps and diaphragms and the spring-actuated arms or
levers can be operated in the required manner by and through any ordinary and
appropriate appliances and may be caused to work at any desired speed which
speed also may be alterable by and through any usual and suitable devices and any
customary and convenient catches and holders and stops and the like can be
provided and properly fitted in any ordinary and suitable manner to retain and
hold the several necessary parts of each apparatus in any of the required positions
and to arrest the movements of such parts also in any of the required positions for
such periods of time as may be deemed expedient which catches and holders aud
stops and the like can be operated whether to be advanced or held or otherwise
put into action or to be retired or released or otherwise put out of action
pneumatically or otherwise by any customary and appropriate appliances.
Any suitable figures or letters or signs or other indicia can most conveniently
be provided with the alterable and adjustable parts of the several apparatus
hereinbefore described such for example as the drum F and boss H2 of the arm H
in respect of Figures 2 and 3 and the quadrant M in respect of Figures 4 and 5 to
afford a knowledge of whatever may be arranged for and may be necessary or
desirable for the proper working of the invention.
It is very convenient also in order to break up and prevent the formation of any
solid and continuous edge to the light rays that pass under or over the edge of the
flap or hood as it is being raised or lowered to form serrations on the edge of the
Hap or to cut short slits therein as is shewn at C' in Figure 3 or to attach a fringe
to the edge of the flap or hood which fringe could be formed of any suitable-
material and in any suitable manner such for example as the lengthwise half of a
feather secured as are the feathers of arrows or a piece of lace or muslin with a
serrated or other edge.
It is very evident therefore that by the varying area of the aperture in the
diaphragm that is in operation as such diaphragm descends or ascends the practical
and photographic proper focussing of even the most distant objects in the view will
be effected although the primary focussing was effected only in relation to the
foreground but this effect can if preferred be enhanced by connecting with this
apparatus through and by any usual and suitable means or devices the screw or
other operative focussing appliance of the lens in such wise that it can be operated
by the movement of such apparatus for the purpose of properly adjusting the focus
upon the arranged for distance during the exposure thereon.
Thus and in this manner in and by and during the cycle of operations hereinbefore
described the several parts of this apparatus are capable of imitating and do imitate
o a very large extent the functions of the upper and lower eyelids the eyelashes
thereon and the iris the pupil and the lens of the eye so far as may be needful or
desirable.

page_text: I have thus described and I have shewn in the accompanying drawing what I
consider to be extremely convenient and efficient forms and styles of construction
and arrangement of the required flap or hood and the required diaphragm but I do
in no wise limit myself,thereto for any flap or hood can be used that can perforn
the required function of uncovering the lens variably and any diaphragm can be
used that can perform the required function of admitting the light rays to the
sensitive surface in the camera through an aperture that varies in size during the
exposure of such sensitive surface while the flap or hood and the diaphragm must
and can and do move in harmony.
For example the flap could be formed of two plates which would be pivoted
together or otherwise above the lens tube and could move on such pivot or pivots
transversely to the line of this lens tube in such wise that their lower parts would
first separate in and with a scissors-like motion uncovering the lower part first of
the aperture of the lens tube and these piates would similarly be operated through
any usual and suitable appliances from or by or with the diaphragm.
Again the hood could be provided with any desired number of ribs similarly
pivoted on the lens tube or on the framing and operated in a similar manner to that
herein before described.
Again the hood could be formed of a number of metallic or other rigid broad ribs
or plates of a curved or semicircular shape in profile each of which plates would in
plan form a section of the perimeter of a sphere and would be pivoted together in
the same manner on each side of the lens tube or of the framing in such wise that
they could be opened out and entirely cover the front of the lens tube in the form
of an half of a sphere each plate sufficiently overlapping the other as to make this
.semispherical hood light tight and could also folded up against the upper part of
the lens tube or of the framing under or inside of one another.
Again the diaphragm could be any ordinary photographic stop or diaphragm or
shutter or other appliance that can slide or revolve or be otherwise actuated to
perform the required function herein before stated.
Again the diaphragm that performs the required function hereinbefore stated as
also the flap or hood may act likewise as the shutter that is or may be required to
entirely close the aperture of the lens tube before and after the desired exposure or
another ordinary shutter may be provided for this purpose and could be actuated
by the apparatus herein before described or any other customary photographic
appliance may be fitted and used for this purpose as may be desired in each
particular.case.
I have thus described this apparatus as arranged to admit the light rays through
the lower part of the aperture of the lens tube to the upper part of the sensitive
surface in the camera or that is to say to take the foreground first but it is obvious
that all the procedure and cycle of operations herein before described can when
desired be reversed and the sky or distant or, more highly lighted objects be taken
first by commencing the exposure with the flap or hood raised to its uppermost
position or thereabouts and the diaphragm in or about or just above its lowermost
position or with the smaller part of its aperture, uncovered and in operation.
Instead also of placing the flap or hood in front of or before the lens and
therefore outside the camera as is hereinbefore described and shewn in the drawing
I may also place the same behind the lens and inside the camera when I may desire
so to do in which case it could be fitted and would operate in the same manner
but obviously it must be inverted to perform the required functions in the same
sequence.
I may point out that this apparatus does not practically or to any injurious
degree interfere with the use of the ordinary photographic stop which can be
inserted in the slot Rshewn in Figure 2 in the customary manner.
When this apparatus is to be used with a single combination lens the diaphragm
can most conveniently be of the "iris" type or of other such style as will close to
and open from the centre to prevent distortion so far as may be possible and, this
diaphragm could be used with or without another shutter as may be preferred and

page_text: the flap or hood would most conveniently be mounted on a tube or cap some little
distance in front of the lens although it may also be mounted in any other
position in respect of the lens as in each particular case may be suitable and
preferable.
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 what I
claim is
1. The method of effecting photographic exposures consisting in admitting light
rays to the sensitive surface in a camera through an aperture that varies in size
during the exposure and in shielding the lens variably so that the light rays may
operate to the best effect substantially as hereinbefore set forth.
2. The combination with a photographic camera of a diaphragm provided with
an aperture that varies in size during the exposure of a sensitive surface and a flap
or hood that moves in harmony with the diaphragm and with the variation in
the size of the aperture in this diaphragmn and thereby shields the lens variably so.
that the light rays may operate to the best effect substantially as hereinbefore
set forth.
3. The combination with the lens tube A of a photographic camera of an hinged
or other Hap C and a sliding or other diaphragm D having an aperture D' and
connected adjustably with the flap C by a cord or the like E' passing over an
elevated drum E' substantially as herein before described.
4. The combination with the lens tube A of a photographic camera of an hinged
or other flap C operated by a spring-actuated arm F¹ and a connecting rod F
a sliding diaphragm D having an aperture D' and suspended from a rocking
lever G and an adjustable arm H on the lever G which can be arranged to
come in contact with the flap C at the desired time substantially as hereinbefore
described.
5. The combination with the lens tube A of a photographic camera of an hinged
or other flap C operated by a spring-actuated rocking lever K through an adjustable-
quadrant M with tail M and a connecting rod M2 and a sliding diaphragm D
having an aperture D2 and connected with and operated by the lever K at
the desired time as arranged by the quadrant M substantially as herein before
described.
6. The combination with the lens tube A of a photographic camera of a pivoted
rib or ribs T carrying or forming an hood V means to operate the rib or ribs T
and a diaphragm D having an aperture D' and connected with the rib or ribs T
substantially as herein before described.
7. The combination with the apparatus hereinbefore described and claimed
of similar but inverted flaps and hoods made and arranged to act invertedly
substantially as herein before set forth.
Dated this 10th day of July 1895.
HART & CO.,
186, Fleet Street, London, E.C., Agents.