Diaphragms for Photographic Lens-tubes.
Year: 1895

page_text: Date of Application, 8th Jan., 1895-Arcepted, 9th Feb.. 1895
Diaphragms for Photographic Lens-tubes.
I, MAX LEVY, of No. 1213 Race Street, Philadelphia, County of Philadelphia
and State of Pennsylvania, United States of America, Manufacturer of Half-tone
and Photo-engraving Apparatus, 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 improvements in diaphragms for photographic leus-
tubes, the same being especially designed for use in the production of half-tone
photo-mechanical engravings, the improvements relating particularly to the means
for producing a negative through a cross-line grating or screen.
The object of the invention is to provide the lens-tube of photographic
cameras with slides for forming a diaphragm the aperture of which may be
varied as to size, and with additional or supplemental slides for altering the
configuration of the aperture; means also being provided for blocking out the
central light; the construction being such that the slides which form the diaphragms
are adjustable for giving any size of rectangular aperture that may be required and
with or without extensions at the corners thereof.
The invention is based upon the fact that in making a so-called half-tone
negative through a cross-line screen the effect is to produce upon the sensitive
plate through each aperture of the screen a perfect reproduction of the aperture in
the diaphragm through which the light is admitted, and in practice. it can be
demonstrated that there are many instances in which the diaphragm with a square
aperture will not give the best results, and this is notably the case where the
subject to be reproduced has relatively high lights and light shadows, or as
commonly expressed the subject is flat and wants contrast or brilliancy, and in such
cases I provide means for extending two or four of the corners of the square
aperture, these extensions being very small as compared to the main aperture and
the light transmitted through them in an ordinary exposure is sufficient to produce
in the highest lights of the subject an action which will respond to the subsequent
processes of intensification. In effect the result is somewhat analogous to the use
of a diaphragm with a small round aperture for the general subject and a larger
aperture for the high lights, but it will be noted that the light admitted by the
excess of the aperture will fall only between the intersections of the opaque lines
of the screen thus greatly exaggerating the tendency to form the dots without
undue loss in the sharpness of the lines. Still further, if a diaphragm with an
aperture of proper size as related to the distance between the screen and sensitive
plate and having the central light blocked out be used for a part only of the entire
exposure the light admitted through the multiple aperture can be made to fall on
the sensitive plate only on those portions between the intersections of the black
cross-lines and the highest lights may be in this way almost entirely acted upon
without detriment to the other parts of the picture.
In practice, in dealing with subjects of greatly varied character it is often found
desirable to change the character of the aperture during the progress of a single
exposure. My invention can be successfully applied in a variety of ways all of
which are essentially dependent upon the same factors; first, that the diaphragms
are so constructed that the aperture produced thereby can be varied in size;

page_text: second, that the character of the aperture can be varied by changing the con-
figuration thereof; third, to provide a diaphragm in which the central light may be
blocked out so as to provide a plurality of apertures; and that these factors be
used singly or in varied combinations.
In the accompanying drawings,
Figure 1 is a view showing a part of the lens-tube with that factor of my
invention applied thereto by means of which there is produced a diaphragm with a
rectangular aperture the size of which may be varied, and in this view one of the
slides is shown in dotted lines;
Fig. 2 is a similar view showing the slides which are used-in producing a diaphragm
with a rectangular aperture with extensions at either two or all of the corners
thereof;
Fig. 3 is a view illustrating the third factor of my invention in which means are
employed for blocking out the central light, or in other words showing the means
employed for providing a diaphragm which forms a series of apertures surrounding
a central opaque portion;
Fig. 4 is a view of the plate which is provided with pins which engage with the
means used for blocking out the central light;
Fig. 5 is, a detail perspective view of one of the slides used for forming the
diaphragm with a rectangular aperture;
Fig. 6 is a view showing the application of my improvement to a camera, the
plate-holder of the camera being adapted to receive the grating and rear of said
grating the sensitive plate upon which the negative is produced; and in this view
the parts of the diaphragms are separated to better show their arrangement;
Fig. 7 is a vertical sectional view of one of the parts of the casing which contains
the diaphragms, and
Fig. 8 is a sectional view of the means employed for adjusting or varying the
position of the slides shown in Figs. 1 and 2.
A designates the lens-tube having lenses arranged therein in the customary
manner. My improvements are applied to the lens-tube between the lenses, and
for this purpose to one of the parts of the lens-tube I attach a disk B, and to said
disk by means of a band b is attached a similar disk B' which is carried by the
other part of the lens-tube to form a casing which contains the slides and means for
actuating the same. The disks are each provided on their inner side with a con-
centric channel and with straight channels 62 which join each other at right
angles, and between these channels are recesses ³ which receive pinions c and d
mounted on suitable bearing screws so that the teeth thereof will enter the said
channels.
C and D designate flat rings which lie in the concentric channels b¹ and are
provided with teeth on their inner edges which engage with the pinions c and d,
and these rings C and D have projecting portions CD' with teeth which project
through a slot in the band b so that the toothed rings can be operated to turn the
pinions.
C2 C3 designate slides having straight edges c and rack-bars c², the rack-bars
being secured to the slides so that when they are placed in the channels 62 the
straight edges c¹ will be at an angle of forty-five degrees with each other.
The teeth of the rack-bars c² engage with the pinions c and when the slides C²
have been arranged in the channels by moving the toothed ring C the pinions c
will be turned in unison and actuate said slides to provide a rectangular or
square aperture of any desired size, and when the ring is turned to its fullest
extent in one direction the slides will be brought together to entirely close the
aperture. The slides D2 which engage with the pinions d are of substantially
the same construction as the slides with the exception that the straight edge d
is provided with a step or cut away portion which forms a rectangular
aperture with extensions at the corners thereof, the width of the extensions
varying with the size of the aperture as the slides are operated by the ring D,
and the length of said extensions are varied by properly positioning the slides D'

page_text: with relation to the slides C2. In practice I prefer to adjust tvo of the slides to
slightly different position from the other two so that the size of the extensions at
the corners of the rectangular aperture will be different; such adjustment or
arrangement of the parts also providing means whereby the slides can be adjuste
so that there will be extensions only at two of the corners of the aperture, and a
further adjustment will produce extensions at all the corners-two of said extensions
varying from the other two. The extensions at the corners of the otherwise
rectangular aperture may also be varied by an adjustment of either one or two of
the slides C² so that the straight edges c thereof will be at a less distance from the
axis of the lens than the others, and when this is done the center of the rectangular
aperture will be to one side of the axis of the lens.
The casing for the diaphragms, which comprises the disks B and B and band b,
also contains a plate E having projecting pins e, and said plate has a circular
aperture corresponding with the apertures in the disks and is held in rigid
engagement with the casing. Upon the plate E is placed a ring E¹ to which are
pivoted four arms E2 of sufficient length to overlap each other at the center of the
opening in the plate E. The arms E' are provided with slots el through which
the pins e pass, and it will be noted that when the ring is turned the arms will be
adjusted to overlap each other at the axis of the lens to block out the central light,
the arms being also adapted to be moved by the ring so as not to interfere with
the aperture formed by the other slides. When the arms are positioned to block
out the central light a diaphragm is provided presenting a plurality of aperture<
surrounding a central opaque portion, and should it be desired to change the size
of the openings it can be done by changing the size of the aperture in one of the
diaphragms over which the arms are swung. The ring E has a projecting portion
with rack-teeth which project through the slot in the band and is engaged by a
pinion carried by a frame attached to said band, the pinion being attached to a
shaft which is actuated by a knob.
F designates a frame which is secured to the band so as to cover the slot
therein through which pass the projecting portions on the rings C and D. The
frame is provided with an enlarged portion F1 with a central recess to receive
pinions, one of the pinions being mounted on a sleeve g to which is rigidly attached
a milled-wheel G. The pinion meshes with the teeth on the projecting portion
of the toothed ring 1). Through the sleeve g passes a shaft to one end of which
is rigidly attached a knob H, a nut being secured upon the opposite end, and a
pinion is attached to the intermediate portion of the shaft so as to be located
within the recess. The pinion i meshes with the teeth on the projecting portion
of the toothed ring C. It will be noted that this construction provides means for
adjusting the slides C2 and D2 together or independently. The milled-wheel G
carries a spring-bar g' which extends over the enlarged portion F¹ of the frame
and engages notches in the periphery of the knob H to lock the knob and wheel
together so that they will move in unison; this construction being provided so that
the slides D can be adjusted to vary the extent of the extensions at the corners
thereof. The notches in the knob H in which the spring-bar lies also serve as
gage-marks from which can be ascertained the extent of the extensions, and the
enlarged portion of the frame F is also provided with gage-marks from which can
be determined the size of the rectangular aperture.
The lens-tube and diaphragms hereinbefore described are used with a camera
having a plate-holder in front of which is secured the usual ruled or lined grating S.
The plate-holder and camera-box may be of any preferred construction, and as
the grating is usually ruled with lines running parallel with the edges of the plate
or diagonally across the same the lens-tube is attached to the camera-box so that
it may be turned to bring the rectangular aperture in the diaphragm in proper
position with respect to the apertures in the grating; for instance, if a diagonally-
ruled grating is employed the sides of the lens-aperture would be vertical.
The construction of the hereinbefore described diaphragms may be varied, as,
for instance, I may provide diaphragms one having a rectangular aperture, another

page_text: with a rectangular aperture having extensions at two of the corners thereof,
another with extensions at all the corners, and another having a plurality of
apertures with a central opaque portion to block out the central light. These may
he arranged to be used independently or consecutively, and I may also vary the
form of the slides, each slide having a complete aperture formed therein so that as
the slides are moved towards the center the size of the aperture will be diminished
each slide being so arranged as to move in unison.
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:
1. A diaphragm for photographic lens-tubes provided with means for producing
a rectangular aperture with extensions at the corners thereof.
2. A diaphragm for photographic lens-tubes provided with means for producing
a variable rectangular aperture with variable extensions at the corners thereof, for
use in the production of half-tone negatives.
3. In a photographic lens-tube, the combination, of a plurality of slides having
straight edges which terminate in a step, means for adjusting said slides to and
from the center of the lens-tube to provide a variable aperture with extended
corners.
4. In a photographic lens-tube, the combination, of a diaphragm having a central
aperture, of arms or bars adapted to be moved across the aperture to block out the
central light.
5. In a diaphragm for photographic lens-tubes for use with a grating, the
combination, of slides which together form a rectangular aperture, similar slides
arranged adjacent thereto for varying the configuration of the aperture.
6. In a diaphragm for photographic lens-tubes for use with a grating, the
combination, of slides which together form a rectangular aperture, similar slides
arranged adjacent thereto for varying the configuration of the aperture, and arms
adapted to be swung across the aperture to block out the central light therefrom.
7. A diaphragm for photographic cameras having two sets of independently
adjustable slides to produce an aperture with different characteristics, the slides
being movable to increase and diminish the size of the aperture, the means for
adjusting the slides being provided with scales from which can be read the size and
configuration of the aperture.
8. In a lens-tube for cameras for use in the production of half-tone negatives,
the combination, of a casing having pinions which mesh with a ring having teeth
on its inner edge, said ring being connected to adjusting means for the same, of a
plurality of slides having rack-bars which mesh with the pinions as shown, whereby
the slides are moved in unison to or away from the center of the casing, for the
purpose set forth.
9. In a lens-tube for use with a grating or screen in the production of half-tone
negatives, the combination, of a diaphragm having a rectangular aperture the sides
of said aperture being arranged at an angle with the lines of the screen so that a
line drawn from one corner of the aperture to the other would be substantially
parallel with the lines of the grating.
Dated this 7th day of January 1894
WALLACE FAIRWEATHER,
Chartered Patent Agent,
62, Saint Vincent Street, Glasgow, Agent for the Applicant.