Year: 1886

page_text: I, WILLIAM JAMES LANCASTER trading as J. Lancaster and Son of Colmore Row
Birmingham in the County of Warwick Optician, do hereby declare the nature of this
invention to be as follows:-
My invention relates to photographic' lens diaphragms, employed in photographic
operations, to determine and regulate the amount of light that shall be admitted into
a camera; thus the time of exposure in photographic operations depends upon the
light upon an object about to be taken, and the size of the aperture of the diaphragm
used with the lens.
Usually a series of various sized diaphragms are employed, or rather a series of
diaphragms with various sized holes. This objectionable, inasmuch as there is no
means of varying the difference between the size of one aperture and the size of one
above or below it, so as to give a mean difference.
By my invention, the diaphragm is made adjustable, so as to be able to control the
size of the aperture, according to the varying requirements and will of the operator ;
thus the aperture in the diaphragm is expanded or enlarged in such a manner, that an
infinite variety of apertures can be readily obtained.
The diaphragms or series of plates which constitute the diaphragm, form a part of
the mount of the lens, thereby avoiding any loose diaphragms or parts whatsoever;
and further, the aperture necessary for certain conditions of light, can be predetermined
by an index finger, before the former of which, the latter travels.
The adjustable diaphragm is constructed as follows...
Within the inside, and crossing the lens tube, is a circular plate or disc with a hole
in its middle, of the full size which the aperture in the diaphragm can acquire; the
diaphragm is a compound or segmental one, made up of a series of thin plates
overlapping each other, but so disposed or arranged with respect to each other, that
their radial curved inside ends or parts enclose a circular or nearly circular space or
opening; so that on the concaved or curved inside edges of the ends of these plates

page_text: being moved or made to approach each other,.a greater .or less aperture or hole is
thereby produced.
The parts constituting the diaphragm, and the manner in which the curved or
crescent inside edges of the plates are made to approach and recede from each other,
is as follows
Each plate of the series of plates, consists of a plate concaved at one end to the
radius or about the radius of the larger sized aperture which the plates will make
when fully opened out or expanded. This curved part forms the inside end of the
plate The other or outside end is pivoted or hung excentrically upon the inside of
the disc, with a hole in its middle as before described. The said pivot forms a centre
upon which the plate turns inwards or outwards, in approaching or receding from the
centre of the lens tube; and situated below, and somewhat in a line with the said
centre, is a stud or pin, upon the face on the side of the plate, which engages and
works within one of a series of radial tangential slots cut within a plate or disc with a
hole in its middle which works or is moved in front of the series of plates by a
protruding arm or finger working through a slot cut in the outside tube of the lens.
Each of the said plates constituting the diaphragm are pivoted, and have studs like
the one described, and each of the said studs of the series, work within the slots as
described; and further, each of the plates over-lap each other, so that the edges of
the one extend over the edges of the other, so as to form as it were, a solid plate,
but with an aperture that is able to be increased or decreased in size at pleasure.
Upon the top outside of the lens tube, and in front or surrounding the slit through
which the finger works, is an index or graduated scale before which the finger is
moved, so that a person can by moving the finger in front of one or other of the
numbers or figures upon the scale, can have the size of aperture required. Thus the
top scale may be 4, 6, 8, 10, 12 onwards, and bottom or second line "speed"
1, 2, 3, 4 &c.
"
The moving of the index finger or arm through a quadrant of a circle for closing, or
for obtaining a smaller aperture, the studs on the plate of the series of plates, which
may be six, eight or any other suitable number, are made to travel down the tangential
slots or slits, and each plate is at the same time turned inwardly upon the pivots upon
which they are hung, thereby causing the curved inside ends to collectively approach
each other, and make a contracted aperture. When a larger aperture is required the
arm or finger is only required to be turned in the reverse direction, when the plates
are collectively made to slide over each other, and recede from the middle or axis of
the lens, by turning excentrically upon the pivot upon which they are hung, and by
the studs on their sides travelling up the slits on the disc or plate wherein they are
formed, being partially rotated.
A supplementary disc with a hole in its middle, comes in front of the plate with
the tangential or inclined slits, in order to preserve or protect the same from injury or
otherwise.
WILLIAM JAMES LANCASTER.
By Henry. Skerrett,
6, Livery Street, Birmingham,
Agent to the Applicant.

page_text: 1, WILLIAM JAMES LANCASTER trading as J. Lancaster and Son of Colmore Row
Birmingham in the County of Warwick, Optician, 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 relates to photographic lens diaphragms employed in photographic
operations, and are employed to determine and regulate the amount of light that should
be admitted into a camera; thus the time of exposure in photographic operations,
depends upon the light upon an object about to be taken, and the size of the aperture
of the diaphragm used with the lens.
Usually a series of various sized diaphragms are employed, or rather a series of
diaphragms with varying sized holes or apertures. This is objectionable, inasmuch as
there is no means of varying the difference between the size of one aperture and the
size of one above or below it, so as to give a mean difference.
By my invention, I employ in a photographic camera a single diaphragm which is
made adjustable, so as to be able to control the size of the aperture, according to the
varying requirements and will of the operator; thus the aperture in the diaphragm
is expanded or enlarged in such a manner, than an infinite variety of apertures can be
readily obtained.
The diaphragms or series of plates which constitute the diaphragm is expanded,
form a part of the mount of the lens, thereby avoiding any loose diaphragms or parts
whatsoever; and further, the aperture necessary for certain conditions of light, can
be predetermined.
The adjustable diaphragm is constructed as follows.
Within the inside, and crossing the lens tube, is a circular plate or disc with a hole
in its middle, of the full size which the aperture in the diaphragın can acquire; the
diaphragm is a compound or segmental one, made up of a series of thin plates over-
lapping each other, but so disposed or arranged with respect to each, that their radiusly
curved inside ends or parts, enclose a circular or nearly circular space or opening; so
that on the concaved or curved inside edges of the ends of these plates, being moved
or made to approach each other, a greater or less aperture or hole is thereby produced.
The parts constituting the diaphragm, and the manner in which the curved or
cresent inside edges of the plates are made to approach and recede from each other, is
as follows.
Each plate of the series of plates, consists of a plate concaved at one end to the

page_text: radius, or about the radius of the larger sized aperture, which the plates will make
when fully opened out or expanded. This curved part forms the inside end of the plate.
The other or outside end is pivoted or hung excentrically upon the inside of the disc,
with a hole in its middle as before described. The said pivot forms a centre upon
which the plate turns inwards or outwards, in approaching or receding from the centre
of the lens tube; and situated below, and somewhat in a line with the said centre, is
a stud or pin, upon the face on the side of the plate, which engages and works within
one of a series of radial tangental slots cut within a plate or disc with a hole in its
middle, which works or is moved in front of the series of plates, by a protruding arm
or snug working through a slot cut in the outside tube of the lens.
Each of the said plates constituting the diaphragm are pivoted, and have studs like
the one described, and each of the said studs of the series, work within the slots as
described; and further, each of the plates overlap each other, so that the edges of the
one extend over the edges of the other, so as to form as it were, a solid plate, but with
an aperture that is able to be increased, or decreased in size at pleasure.
Upon the top outside of the lens tube, and in front or surrounding the slit through
which the stud or finger works, is an index or graduated scale, before which the stud
or finger is moved, so that a person can by moving the finger in front of one or other
of the numbers or figures upon the scale, can have the size of aperture required. Thus
the top scale may be 4, 6, 8, 10, 12 onwards, and bottom or second line "speed
1, 2, 3, 4 &c.
"
The moving of the index finger or ring through a quadrant of a circle for closing,
or for obtaining a smaller aperture, the studs on the plate of the series of plates, which
may be six, eight or any other suitable number, are made to travel down the tangential
slots or slits, and each plate is at the same time turned inwardly upon the pivots upon
which they are hung, thereby causing the curved inside ends to collectively approach
each other, and make a contracted aperture. When a larger aperture is required, the
arm or finger is only required to be turned in the reverse direction, when the plates
are collectively made to slide over each other, and recede from the middle or axis of
the lens, by turning excentrically the pivot upon which they are hung, and by the
studs on their sides, travelling up the slits on the disc or plate wherein they are formed,
being partially rotated.
A supplementary disc with a hole in its middle, comes in front of the plate with
the tangential or inclined slits, in order to preserve or protect the same from injury or
otherwise.
I will now proceed to describe with reference to the accompanying Drawings, the
manner in which the same is to be performed.
Figure 1 represents in front elevation and part in vertical section, a photographic
camera lens mount, provided with an adjustable diaphragm made according to my
invention, and with the aperture extended to its full extent, and also with the front
covering plate removed, in order to exhibit the tangental like slots in the operating
plate. Figure 2 represents the same as figure 1, but with the tangential slot operating
plate removed (other than a small portion). Figure 3 is a longitudinal vertical section
of figure 1. Figure 4 shows exactly the same view as figure 1, but with the adjustable
diaphragm or the plates constituting the adjustable diaphragm closed or nearly so.
Figure 5 is a like view to figure 4, but with the tangental slotted operating plate
removed, in order to exhibit the overlapping and working of the thin plates consti-
tuting the adjustable diaphragm, Figure 6 is a front elevation and side elevation of
the tangental slotted operating plate, and figure 7 is a front and side elevation of one
of the series of plates, which make up the adjustable diaphragm. Figure 8 is a
perspective view of the said lens mount and adjustable diaphragm.
The same letters of reference indicate corresponding parts in the several figures of
the drawings.
a
is the lens tube, or mount of the lens, and a² is its attachment flange. 6 is a front
disc or diaphragm with a hole b² at its middle, equal or about equal to the full size
which the aperture in the diaphragm can acquire. c is an adjustable diaphragm,

page_text: composed of a series of thin plates c² overlapping each other, and so disposed or
arranged, that their radiusly curved inside gapped parts enclose or nearly enclose a
circular opening, forming an aperture, through which light passes, and by such means,
a greater or less aperture can be obtained, by making the gapped parts c² approach to,
or recede from each other.
Each of the said plates is hung or suspended by excentrically arranged studs or
pins c, which work in bearing holes d² in the partition or carrying plate d. The said
pins or studs et form pivot centres, upon which the plates turn inwards or outwards,
in making a greater or less aperture.
The lower parts of these plates are provided with (and upon the opposite sides) studs
or pins, which work in tangental like slots e² in the operating plate e, and which said
plate is provided with a stud or snug e³, which is carried by a rotating sleeve f which
on being turned or rotated in one or other direction, increases or decreases the
diaphragm aperture.
The lens tube a is slotted or cut away, for the working therein of the stud e³, which
is limited in its motion by the ends of the said slotted part.
The fixed part or collar of the lens tube a is marked with a graduated scale, indi-
cative of time degrees, and on the other or movable part f, letters and figures, or other
indications are placed, as best seen in the perspective view figure 8; so that on points
of the latter being brought opposite figures of the former, it is known that the aperture
is open or has been opened to the desired extent.
Thus the moving or turning of the ring through a portion of a circle, gives a like
rotation to the operating plate e, and causes the studs c to traverse down the tangental
slots e and thereby cause the lower ends, or the curved gapped parts c³ of the lower
ends, to simultaneously and collectively approach to or recede from each other, and
make a circular or nearly circular aperture as may be desired.
Instead of employing an operating ring f, a finger or pointer may be substituted
therefore.
Although I have described that the plates are hung and drawn together towards a
common centre, by a tangental slotted plate, yet the gapped or inside ends of the said
plates may be moved towards each other radially, and in a sliding manner, instead of
by a swinging action. Thus the plates which have their inner ends overlapping each
other, may be drawn or taken away from a common centre, by crank or wormed gear
arrangements, operated by an encircling ring with which they are connected; so that
the rotation of the ring, causes the plates to slide radially, so as to increase or decrease
the distance, between the gapped curved parts presented and forming the boundary line
to the aperture.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that I am aware that
diaphragms with adjustable apertures such as those of what are termed Iris diaphragms
have been used before and I do not claim them generally as of my invention, but what
I claim is :-
--
First. A photographie lens diaphragm, or a diaphragm for photographie purposes,
with, or provided with, an adjustable aperture or opening, which admits of a variable
expansion and contraction, and which said diaphragm consists of a series of thin plates
(or two or more plates) or the equivalents of plates, which respectively overlap or
underlap each other, preferably at their inner radiusly enrved gapped parts; so that
on the said plates or their equivalents being collectively moved to, or away from a
common centre, a varying sized circular, or nearly circular, or other chaped aperture
or opening, is thereby obtained.
Secondly. An adjustable photographic lens diaphragm, consisting of a series of
pivoted swinging plates, which overlap or work one upon another in such a manner,
that their inner concaved gapped parts, are made to enclose and form an aperture,
more or less eircular; and which said plates are operated, or opened out, or drawn
together, for giving a greater or less opening by a plate (turned by a ring or finger)
provided with; or having cut therein, tangentally or other excentrically arranged slots

page_text: er gaps, wherein pins or their equivalents carried by the said plates, work, the parts
being arranged, combined and operated, in the manner, and for the purpose herein
described and set forth.
Thirdly. A photographie lens diaphragm with an adjustable aperture, composed of
a series of overlapping radially disposed plates, with their inner ends concaved or
gapped, which on being radially drawn together, or opened out, produce varying sized
apertures, substantially as described.
Fourthly-Combining with a lens tube, an adjustable fixed diaphragm, in a
photographic camera substantially as and for the purpose herein described. Also
providing combined lense tubes and adjustable diaphragms with graduated scales or
equivalents thereof, for the purpose substantially as described and set forth.

page_text: 1886.
Date of Application, 19th Mar.,
Complete Left, 20th Dec., 1886.
Complete Accepted, 8th Feb., 1887
I, WILLIAM JAMES LANCASTER trading as J. Lancaster and Son of Colmore Row
Birmingham in the County of Warwick Optician, do hereby declare the nature of this
invention to be as follows:—
My invention relates to photographic lens diaphragms, employed in photographic
operations, to determine and regulate the amount of light that shall be admitted into
a camera; thus the time of exposure in photographic operations depends upon the
light upon an object about to be taken, and the size of the aperture of the diaphragni
used with the lens.
Usually a series of various sized diaphragms are employed, or rather a series of
diaphragms with various sized holes. This is objectionable, inasmuch as there is no
means of varying the difference between the size of one aperture and the size of one
above or below it, so as to give a mean difference.
•
By my invention, the diaphragm is made adjustable, so as to be able to control the
size of the aperture, according to the varying requirements and will of the operator ;
thus the aperture in the diaphragm is expanded or enlarged in such a manner, that an
infinite variety of apertures can be readily obtained.
The diaphragms or series of plates which constitute the diaphragm, form a part of
the mount of the lens, thereby avoiding any loose diaphragms or parts whatsoever;
and further, the aperture necessary for certain conditions of light, can be predetermined
by an index finger, before the former of which, the latter travels.
The adjustable diaphragm is constructed as follows.
Within the inside, and crossing the lens tube, is a circular plate or disc with a hole
in its middle, of the full size which the aperture in the diaphragm can acquire; the
diaphragm is a compound or segmental one, made up of a series of thin plates
overlapping each other, but so disposed or arranged with respect to each other, that
their radial curved inside ends or parts enclose a cirerlar or nearly circular space or
opening so that on the concaved or curved inside edges of the ends of these plates

page_text: being moved or made to approach each other, a greater or less aperture or hole is
thereby produced.
The parts constituting the diaphragm, and the manner in which the curved or
crescent inside edges of the plates are made to approach and recede from each other,
is as follows
Each plate of the series of plates, consists of a plate concaved at one end to the
radius or about the radius of the larger sized aperture which the plates will make
when fully opened out or expanded. This curved part forms the inside end of the
plate The other or outside end is pivoted or hung excentrically upon the inside of
the disc, with a hole in its middle as before described. The said pivot forms a centre
upon which the plate turns inwards or outwards, in approaching or receding from the
centre of the lens tube; and situated below, and somewhat in a line with the said
centre, is a stud or pin, upon the face on the side of the plate, which engages and
works within one of a series of radial tangential slots cut within a plate or disc with a
hole in its middle which works or is moved in front of the series of plates by a
protruding arm or finger working through a slot cut in the outside tube of the lens.
Each of the said plates constituting the diaphragm are pivoted, and have studs like
the one described, and each of the said studs of the series, work within the slots as
described and further, each of the plates over-lap each other, so that the edges of
the one extend over the edges of the other, so as to form as it were, a solid plate,
but with an aperture that is able to be increased or decreased in size at pleasure.
Upon the top outside of the lens tube, and in front or surrounding the slit through
which the finger works, is an index or graduated scale before which the finger is
moved, so that a person can by moving the finger in front of one or other of the
numbers or figures upon the scale, can have the size of aperture required. Thus the
top scale may be 4, 6, 8, 10, 12 onwards, and bottom or second line " speed
1, 2, 3, 4 &c.
"
The moving of the index finger or arm through a quadrant of a circle for closing, or
for obtaining a smaller aperture, the studs on the plate of the series of plates, which
may be six, eight or any other suitable number, are made to travel down the tangential
slots or slits, and each plate is at the same time turned inwardly upon the pivots upon
which they are hung, thereby causing the curved inside ends to collectively approach
each other, and make a contracted aperture. When a larger aperture is required the
arm or finger is only required to be turned in the reverse direction, when the plates
are collectively made to slide over each other, and recede from the middle or axis of
the lens, by turning excentrically upon the pivot upon which they are hung, and by
the studs on their sides travelling up the slits on the disc or plate wherein they are
formed, being partially rotated.
A supplementary dise with a hole in its middle, comes in front of the plate with
the tangential or inclined slits, in order to preserve or protect the same from injury or
otherwise.
WILLIAM JAMES LANCASTER.
By Henry Skerrett,
6, Livery Street, Birmingham,
Agent to the Applicant.

page_text: A New or Improved Adjustable Diaphragm for Photographic
Cameras.
I, WILLIAM JAMES LANCASTER trading as J. Lancaster and Son of Colmore Row
Birmingham in the County of Warwick, Optician, 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 relates to photographic lens diaphragms employed in photographic
operations, and are employed to determine and regulate the amount of light that should
be admitted into a camera; thus the time of exposure in photographic operations,
depends upon the light upon an object about to be taken, and the size of the aperture
of the diaphragm used with the lens.
Usually a series of various sized diaphragms are employed, or rather a series of
diaphragms with varying sized holes or apertures. This is objectionable, inasmuch as
there is no means of varying the difference between the size of one aperture and the
size of one above or below it, so as to give a mean difference.
By my invention, I employ a single diaphragm which is made adjustable, so as to
be able to control the size of the aperture, according to the varying requirements and
will of the operator; thus the aperture in the diaphragm is expanded or enlarged in
such a manner, than an infinite variety of apertures can be readily obtained.
The diaphragms or series of plates which constitute the diaphragm is expanded,
form a part of the mount of the lens, thereby avoiding any loose diaphragms or parts
whatsoever; and further, the aperture necessary for certain conditions of light, can
be predetermined.
The adjustable diaphragm is constructed as follows.
Within the inside, and crossing the lens tube, is a circular plate or disc with a hole
in its middle, of the full size which the aperture in the diaphragm can acquire; the
diaphragm is a compound or segmental one, made up of a series of thin plates over-
lapping each other, but so disposed or arranged with respect to each, that their radiusly
curved inside ends or parts, enclose a circular or nearly circular space or opening; so
that on the concaved or curved inside edges of the ends of these plates, being moved
or made to approach each other, a greater or less aperture or hole is thereby produced.
The parts constituting the diaphragm, and the manner in which the curved or
cresent inside edges of the plates are made to approach and recede from each other, is
as follows.
Each plate of the series of plates, consists of a plate concaved at one end to the
radius, or about the radius of the larger sized aperture, which the plates will make
when fully opened out or expanded. This curved part forms the inside end of the plate.
The other or outside end is pivoted or hung excentrically upon the inside of the disc,
with a hole in its middle as before described. The said pivot forms a centre upon
which the plate turns inwards or outwards, in approaching or receding from the centre
of the lens tube; and situated below, and somewhat in a line with the said centre, is
a stud or pin, upon the face on the side of the plate, which engages and works within
one of a series of radial tangental slots cut within a plate or disc with a hole in its
middle, which works or is moved in front of the series of plates, by a protruding arm
or snug working through a slot cut in the outside tube of the lens.
Each of the said plates constituting the diaphragm are pivoted, and have studs like
the one described, and each of the said studs of the series, work within the slots as
described; and further, each of the plates overlap each other, so that the edges of the

page_text: one extend over the edges of the other, so as to form as it were, a solid plate, but with
an aperture that is able to be increased, or decreased in size at pleasure.
Upon the top outside of the lens tube, and in front or surrounding the slit through
which the stud or finger works, is an index or graduated scale, before which the stud
or finger is moved, so that a person can by moving the finger in front of one or other
of the numbers or figures upon the scale, can have the size of aperture required. Thus
the top scale may be 4, 6, 8, 10, 12 onwards, and bottom or second line "speed"
1, 2, 3, 4 &c.
The moving of the index finger or ring through a quadrant of a circle for closing,
or for obtaining a smaller aperture, the studs on the plate of the series of plates, which
may be six, eight or any other suitable number, are made to travel down the tangential
slots or slits, and each plate is at the same time turned inwardly upon the pivots upon
which they are
hung, thereby causing the curved inside ends to collectively approach
each other, and make a contracted aperture. When a larger aperture is required, the
arm or finger is only required to be turned in the reverse direction, when the plates
are collectively made to slide over each other, and recede from the middle or axis of
the lens, by turning excentrically the pivot upon which they are hung, and by the
studs on their sides, travelling up the slits on the disc or plate wherein they are formed,
being partially rotated.
A supplementary disc with a hole in its middle, comes in front of the plate with
the tangential or inclined slits, in order to preserve or protect the same from injury or
otherwise.
I will now proceed to describe with reference to the accompanying Drawings, the
manner in which the same is to be performed.
Figure 1 represents in front elevation and part in vertical section, a photographic
camera lens mount, provided with an adjustable diaphragm made according to my
invention, and with the aperture extended to its full extent, and also with the front
covering plate removed, in order to exhibit the tangental like slots in the operating
plate. Figure 2 represents the same as figure 1, but with the tangential slot operating
plate removed (other than a small portion). Figure 3 is a longitudinal vertical section
of figure 1. Figure 4 shows exactly the same view as figure 1, but with the adjustable
diaphragm or the plates constituting the adjustable diaphragm closed or nearly so.
Figure is a like view to figure 4, but with the tangental slotted operating plate
removed, in order to exhibit the overlapping and working of the thin plates consti-
tuting the adjustable diaphragm, Figure 6 is a front elevation and side elevation of
the tangental slotted operating plate, and figure 7 is a front and side elevation of one
of the series of plates, which make up the adjustable diaphragm. Figure 8 is a
· perspective view of the said lens mount and adjustable diaphragm.
The same letters of reference indicate corresponding parts in the several figures of
the drawings.
a is the lens tube, or mount of the lens, and a² is its attachment flange. is a front
disc or diaphragm with a hole 2 at its middle, equal or about equal to the full size
which the aperture in the diaphragm can acquire. is an adjustable diaphragm,
composed of a series of thin plates 2 overlapping each other, and so disposed or
arranged, that their radiusly curved inside gapped parts enclose or nearly enclose a
circular opening, forming an aperture, through which light passes, and by such means,
a greater or less aperture can be obtained, by making the gapped parts approach to,
72
or recede from each other.
Each of the said plates is hung or suspended by excentrically arranged studs or
pins e, which work in bearing holes d² in the partition or carrying plate d. The said
pins or studs et form pivot centres, upon which the plates turn inwards or outwards,
in making a greater or less aperture.
The lower parts of these plates are provided with (and upon the opposite sides) studs
or pins, which work in tangental like slots in the operating plate e, and which said
plate is provided with a stud or snug e³, which is carried by a rotating sleeve which
on being turned or rotated in one or other direction, increases or decreases the
diaphragm aperture,

page_text: The lens tube a is slotted or cut away, for the working therein of the stud e³, which
is limited in its motion by the ends of the said slotted part.
The fixed part or collar of the lens tube a is marked with a graduated scale, indi-
cative of time degrees, and on the other or movable part f, letters and figures, or other
indications are placed, as best seen in the perspective view figure 8; so that on points
of the latter being brought opposite figures of the former, it is known that the aperture
is open or has been opened to the desired extent.
Thus the moving or turning of the ring through a portion of a circle, gives a like
rotation to the operating plate e, and causes the studs to traverse down the tangental
slots and thereby cause the lower ends, or the curved gapped parts of the lower
ends, to simultaneously and collectively approach to or recede from each other, and
make a circular or nearly circular aperture as may be desired.
Instead of employing an operating ring f; a finger or pointer may be substituted
therefore.
Although I have described that the plates are hung and drawn together towards a
common centre, by a tangental slotted plate, yet the gapped or inside ends of the said
plates may be moved towards each other radially, and in a sliding manner, instead of
by a swinging action. Thus the plates which have their inner ends overlapping each
other, may be drawn or taken away from a common centre, by crank or wormed
arrangements, operated by an encircling ring with which they are connected; so that
the rotation of the ring, causes the plates to slide radially, so as to increase or decrease
the distance between the gapped curved parts presented and forming the boundary line
to the aperture.
gear
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is :-
First. A photographic lens diaphragm, or a diaphragm for photographic purposes,
with, or provided with, an adjustable aperture or opening, which admits of a variable
expansion and contraction, and which said diaphragm consists of a series of thin plates
(or two or more plates) or the equivalents of plates, which respectively overlap or
underlap each other, preferably at their inner radiusly curved gapped parts; so that
on the said plates or their equivalents being collectively moved to, or away from a
common centre, a varying sized circular, or nearly circular, or other shaped aperture
or opening, is thereby obtained.
Secondly. An adjustable photographic lens diaphragm, consisting of a series of
pivoted swinging plates, which overlap or work one upon another in such a manner,
that their inner concaved gapped parts, are made to enclose and form an aperture,
more or less circular; and which said plates are operated, or opened out, or drawn
together, for giving a greater or less opening by a plate (turned by a ring or finger)
provided with, or having cut therein, tangentally or other excentrically arranged slots
or gaps, wherein pins or their equivalents carried by the said plates, work, the parts
being arranged, combined and operated, in the manner, and for the purpose herein
described and set forth.
Thirdly. A photographic lens diaphragm with an adjustable aperture, composed of
a series of overlapping radially disposed plates, with their inner ends concaved or
gapped, which on being radially drawn together, or opened out, produce varying sized
apertures, substantially as described.
Fourthly. Combining with a lens tube, an adjustable fixed diaphragm. Also
providing combined lense tubes and adjustable diaphragms with graduated scales or
equivalents thereof, for the purpose substantially as described and set forth.