Improvements in Iris-diaphragms for Photographic Objectives, and in Mechanisms for using same as Objective Shutters.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Iris-diaphragms for Photographic Objectives, and
in Mechanisms for using same as Objective Shutters.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of
Middlesex Gentleman do hereby declare the nature of this invention (which has
been communicated to me from abroad by the Firm of Carl Zeiss of Carl Zeiss
Strasse, Jena, Grand Duchy of Saxe-Weimar in the Empire of Germany,
Manufacturers of Optical Instruments) 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 iris-diaphragms for photographic objectives and consists
in improvements of such diaphragms and in mechanisms for using the same as
objective shutters for time as well as for instantaneous exposures without prejudicing
the employment of the iris as a mere diaphragm of adjustable aperture for
focussing the object or for exposures at which a special cover is used as the objective
shutter.
For the purpose of allowing absolutely instantaneous exposures and of excluding
any interruption of the working, the mechanism of the iris is so arranged that the
blades move with the least frictional or other resistance and cannot be deformated
or interfere with each other; thus avoiding the defect common to iris-diaphragms;
that in rapid closing, the hook shaped inner ends of the blades strike into each other
so as to stop the movement before the aperture is completely covered.
And in order that the said invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the
several figures on the annexed sheet of drawings the same letters of reference
indicating corresponding parts in all the figures.
Fig. 1 is a front view of the iris-diaphragm, the casing being in section transverse
to the axis.
Fig. 2 shows a section through the iris diaphragm and its casing at right angles
to Fig. 1.
Figs. 3 and 4 represent a front and a side view of the ring which embraces and
operates the blades of the iris diaphragm.
The casing of the diaphragm which is inserted into the objective tube by means
of two tubular projections f.and g is formed by two circular cups a and b, one
covering the other, and each possessing a suitably wide central, circular aperture.
The blades c are fitted on the cup a by means of screws h so that they are capable
of a limited movement, each of them in a plane parallel to the others. The iris
shewn in Figure 1 is formed by nine blades co to e8, the first blade co and the last
blade being mounted on a common axis 8 for the purpose of securing a light
tight closing at the point where the blades c¹ and overlap there being there a
distance of some millimeters between each.
The peculiarity of the mechanism consists in the arrangement of the connections
of the blades c with the operating ring d, fitted inside the casing and which can be
turned therein in both directions by means of the stud e extending through a slot in
the said casing. The ring d is provided with radial slots i opening into the cavity
of the ring so that the heads of the iris-blades are able to enter the slots i in a
radial direction.
It is evident, that the head of every blade being situated in or about the same
plane as the pivoted blade itself and the neck part connecting the body of the blade
with the head being also situated in the same plane, there is no occasion for the
blades to become deformed or to move out of their different parallel planes owing to
a quick oneration of rino d.

page_text: The blades c may be made of any material that is impermeable to actinic light,
for example, they may be punched from thin sheet steel or, as shown in the drawing
in order to obviate the influence of moist air, and to avoid any reflection of light
the bodies of the blades may consist of opaque-black hardened caoutchouc, a leaf
of steel forming the head and the pivoted shield of the blade being rivetted to
the body.
It is important that the described construction allows of a minute thickness of the
body of the iris; thus it may be used for photographic doublets, as for example in
the Zeiss Anastigmata, which leave but a very small interval between the two
components of the lense system.
The apparatus for operating the iris-diaphragm as a shutter is a combination of
several mechanisms, which may be made with various modifications. Although
this invention embraces a number of distinct apparatus resulting from the successive
variations of the component mechanisms, it will however be sufficient for clearly
explaining the object of the invention, to describe but three complete apparatus,
which together comprise all modifications of every single mechanism. The
corresponding parts of the several apparatus, are indicated by the same letters of
reference in all the figures.
Figure 5 represents a sectional view of an apparatus according to this invention
arranged on the top of the casing of the diaphragm, Figure 6 is a plan, and
Figure 7 an elevation corresponding to the vertical section in Figure 5 but shewing
the apparatus with its protective cover.
A modification is shewn in the Figures 8 and 9, the former figure being an
elevation partly in section, the latter a complete section, both transverse to the axis
of the objective.
A third modification is shewn in Figures 10 and 11 which represent a front view
in two positions, and in Figure 12 which is a rear view of the same.
Figure 13 is a section parallel to the axis of the objective, Figure 14 is a front
view and Figure 15 a side view of the plate (partly in section) whereon the
apparatus is mounted.
The essential feature of the invention illustrated by Figures 5 to 15 consists in
the arrangement of a driver pivoted at n to a holder m and pressed by means of
a spring o towards a stop p on the said holder. The driver is adapted to engage
the operating pine of the iris diaphragm whenever the holder m is moved forward
by means of a suitable appliance, and ceases to push the pine when its point slides
over the same. The more the pin e is driven forward before it is disengaged from
the driver, the more the iris is opened, and so by displacing the path of travel of
the point of the driver the degree of aperture of the iris diaphragm may be
regulated. A spring fixed at one end to the iris casing and connected at its
other end to the pin e recloses the iris diaphragm by drawing backward the said pin
as soon as it is released from the driver.
When the holder m returns to its original position the driver slides backwards.
over the pin e being able to yield by turning on its axis at n in a direction contrary
to the strain of the spring o.
For long exposures a regulatable stop, for instance a cams (Figures 5 and 6,)
a screw (Figures 8 and 9,) or a small sliding rod which may be fixed by a
pinching screws (Figure 10) is mounted on the top of the casing and opposite to
the pin e. By means of this stop the stroke of the pine can be limited, so that
the path of the holder being suitably adjusted the driver is prevented from passing
over the pin e. In this case the exposure will last with the adjusted aperture as
long as the motive appliance acts on the holder, and the iris will be reclosed only
when the holder is caused to return, whereby the driver is also drawn back allowing
the spring to close the iris. On the other side of the pin e a second adjustable
stop may be arranged for instance a set screw & Figures 8 and 9, for the purpose
of fixing the iris in any position as a mere diaphragm with a smaller, or greater
aperture.
The path of travel of the driver may be straight or circular and its displacement

page_text: or adjustment may be effected in different ways. In the first example (Fig. 5 to 7)
the holder m moves in a straight line being guided in the cylinder m'. The
direction of this line may be changed by turning an eccentric ring m² surrounding
the outer end of the cylinder m' so that the said end is raised against or lowered by
a spring u² which keeps the outer end of the cylinder against the support plate u,
whilst the inner end of the said cylinder is pivoted at u' to the plate u.
In the modification shewn in Figs. 8 and 9, the holder m is likewise guided in a
straight line within a cylinder m', but in this case the displacement of the path of
travel of the driver point is effected by merely turning the driver on its pivot n.
For this purpose the stop p is made adjustable by being formed as a screw, being
guided between projections p' of the cover p³ for the purpose of being adjusted by
turning the said cover.
+
In the third modification, Figs. 10 to 13, the motion of the holder m is circular,
the holder being carried by a casing q' pivoted at us to the plate u. The path of
travel of the point of the driver is regulated by turning a set-screw q³ adapted to
move the driver / in a dove-tailed groove 70 (Fig. 11) of the casing q¹.
In order to prevent the iris being opened (by inertia of the blades) wider than is
intended by adjustment of the driver, the herein before described mechanisms for
limiting the stroke of the operating pin e may be used, so as to stop the said pin at
the moment the point of the driver slides over it.
The motive appliance employed for operating the apparatus may be of any
suitable kind. In the first and second examples air-bellows t, which are connected
by a tube t to a rubber ball (not shown in the drawing) adapted to be pressed by
hand, effect the forward movement of the holder m, whilst a spiral spring t¹ effects
the rearward movement.
น
In the third example a motive spring q is employed with its exterior end secured
to a point g² of the support plate u and with its interior end to a spring casing g¹
pivoted at u to the plate u. A handle q on the casing serves to compress the
spring g by turning the said casing in the direction of the hands of a watch, a bell
crank lever a being arranged to stop this movement by means of the hook-shaped
end of its arm engaging with a pin 9 on the casing. To release the spring the
arm which is held against the casing by a spring is swung rearward. In the
example shewn in the drawing the second arm 2 of the lever is connected for this
purpose to air bellows contained in the casing and actuated by a hand rubber
ball (not shown in the drawing).
For the purpose of obtaining with different apertures of the iris the same total
length of time of exposure corresponding to the speed of the driver, instead of the
spring used in the two first examples which takes back the operating pin e to the
position at which the iris is closed, a double armed lever v¹³ may be used which is
arranged in such a way, that the driver or its holder m after the said driver has
slipped over the pin e pushes against the arm by means of a projection w, whereby
the arm v draws back the pin e to its initial position. In the Figs. 10 to 13 this
arrangement is shown with the projection w fixed to the casing g'or the projection w
may be fixed to the holder m.
The same arrangement of a double armed lever v¹² may likewise be used for
long exposures, if the catching mechanism which holds the casing in a ready
position, is combined with another one which limits the movement of that casing
just before the arm vis touched by the projection w, so as to demand a second
release of the spring casing at any time in order to get the iris closed.
As shown in Figs. 10 and 11 a second catching pin is arranged for this
purpose on the casing q' in the path of the hook-shaped end of the lever 21 so as to
engage the said lever. To enable the iris-shutter to be opened and closed if
desired by one release of the spring, as hereinbefore described, the peg 9° is
mounted on the axis of a hand lever so that it may be turned aside and out of
the path of the hook-shaped lever x¹.
The third example shows an arrangement for regulating the speed of the driver.
The casing q' behind the plate u (Figs. 12 and 13) carries a crank g', the pin of

page_text: which engages in a slot y' of a link y mounted upon an axis y³. In a second slot y
of the link engages a pin on the piston-rod of an exhaust-brake z, the air
openings of which may be adjusted by means of a rotative slide 23. According to
the position of this rotative slide the brake will more or less retard the rotation of
the casing q¹ when connected thereto by the arrangement described. At the front
end of the axis y a button y' is provided between which and the plate a spiral
spring y holds the said axis in the position, in which the link y engages the
pins and 23. By pressing upon the button the link y slips off the pins q¹º and z³
and may be turned aside, whereby the exhaust-brake z is set out of operation and
the apparatus is prepared for the shortest exposure.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what I
claim is.
1. In photographic objectives having a completely closing iris-diaphragm, for
the purpose of using the latter as a shutter for any required aperture, the combina-
tion with a pin e secured to the operating ring d of the iris, of a driver / which is
carried by a holder m in the adjustable path of which the said pin projects and by
the forward movement of which it is displaced so as to open the iris diaphragm till
the point of the driver slips over the pin-and of a spring r adapted to draw back
again the operating ring into the position in which the iris is closed, the driver
being pivotally mounted on the holder and held in its position by a stop p and a
spring o in the manner and for the purpose of sliding yieldingly over the pin at the
rearward movement of the holder, substantially as herein before described and
illustrated in Figures 5. 6. 7. 8 and 9 of the accompanying drawings.
2. In photographic objectives having a completely closing iris-diaphragm and
means for using the same as a shutter, the combination with an adjustable stop for
the operating pine of the iris, of a pneumatic device t adapted to drive forward the
holder against the tension of a spring t' for the purpose of keeping open the iris in
the aperture which is adjusted by the stop, as long as the pneumatic pressure lasts,
the path of the driver being adjusted in such a manner, that the operating pin is
stopped before the point of the driver is disengaged from it, substantially as herein-
before described and illustrated in Figures 5. 6. 7. 8 and 9 of the accompanying
drawings.
3. In photographic objectives having a completely closing iris-diaphragm and
means for using the same as a shutter, the combination with means for guiding the
holder in a rectilinear direction, of means m³ for adjusting the direction of the
guiding contrivance m¹ for the purpose of adjusting the path of the driver point,
substantially as herein before described and illustrated in Figures 5. 6 and 7 of the
accompanying drawings.
4. In photographic objectives having a completely closing iris-diaphragm and
means for using the same as a shutter, for the purpose of adjusting the path of the
driver point, an adjustable stop in place of the fixed stop p controlling the position
of the driver on the holder, substantially as hereinbefore described and illustrated
in Figures 8 and 9 of the accompanying drawings.
5. In photographic objectives having a completely closing iris-diaphragm and
means for using the same as a shutter, the combination with means for turning the
holder around a fixed point of means for adjusting the said holder in a radial
direction for the purpose of adjusting the path of the driver point substantially as
hereinbefore described and illustrated in Figures 10. 11. 12. 13. 14 and 15 of the
accompanying drawings.
6. In photographic objectives having a completely closing iris-diaphragm and
means for using the same as a shutter in place of the spring which returns the
iris to its closed position, a double-armed lever arranged in such a manner
that a projection w on the driver or holder or other suitable part connected thereto
meets one arm of the lever, after the driver point has slipped over the operating
pin, and that the lever driven thereafter by the said part w pushes by its other arm

page_text: the operating pin to the position, in which the iris is closed, substantially as
hereinbefore described and illustrated in Figures 10 and 11 of the accompanying
drawings.
7. In photographic objectives having a completely closing iris-diaphragm and
means for using the same as a shutter, the combination with a device for
releasing a motive spring for the holder, of a catching device 9 which catches
the holder or any suitable part connected thereto before the driver reaches the
lever so that the exposure lasts with the adjusted aperture of the iris
till a second release allows of the holder continuing its way and of turning the
lever so as to close the iris, substantially as hereinbefore described and illustrated
in Figures 10 and 11 of the accompanying drawings.
8. In photographic objectives an iris-diaphragm the pivoted blades c of which
enter readily by their exterior parts the guiding slots i of the operating ring d
for the purpose of reducing friction and securing efficiency of work substantially
as hereinbefore described and illustrated in Figures 1. 2. 3 and 4 of the accom-
panying drawings.
Dated this 8th day of November 1902
J. H. JOHNSON & Co.,
Agents.