Improvements in or connected with Shutters for Photographic Cameras for Adapting them to Lens Hoods or Mounts of Different Sizes.
Year: 1890

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PROVISIONAL SPECIFICATION.
Improvements in or connected with Shutters for Photographic
Cameras for Adapting them to Lens Hoods or Mounts of
Different Sizes.
We, JOHN EDWARD THORNTON, and EDGAR PICKARD, both of St. Mary's Street,
Deansgate, Manchester, in the County of Lancaster, Manufacturers, do hereby declare
the nature of this invention to be as follows:-
This invention provides improved means for adapting photographic shutters to lens
mounts or hoods, so that shutters having openings of suitable standard sizes may be
readily fitted to lenses of intermediate sizes.
In carrying out our invention we provide rubber bands or packing of suitable
sectional form, as hereinafter described, for insertion in the aperture in the back of
the photographic shutter.
Through the side of the shutter case we fit a screw so that the end thereof may
press behind the rubber band. By turning the screw inwards or outwards respectively
the diameter of the aperture can be diminished or increased.
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By making the bands of various thicknesses-for instance 16" """-an
ample range of sizes is obtained, whilst the screw permits of any intermediate
adjustinent.
The rubber band is formed with one edge rounded or bevelled, and the other with a
projecting rib thereon. When the band is inserted in the shutter aperture the
bevelled or rounded edge of the rubber makes the aperture of "bell-mouth" shape, so
that the lens-hood or mount may be easily pushed in, whilst the rib forms a stop.
which prevents it from going in too far.
In order that the band may fit tightly within the aperture, we find it necessary
that the thin or rounded edge shall be longer than the thick or ribbed edge, so that:
the thin edge may have a greater tendency to spring outwards when inserted in the
aperture. This we obtain by forming the band in circular or semi-circular flat strips
having the rib on the inner or shorter edge. Such a band, when made of moderately
hard rubber, and sprung edgewise into the aperture, serves the purpose required.
By another method we dispense with the rib, and simply use a plain flat band, in
which case the requisite stop is formed by using a flat ring or washer of the required
size, which is inserted in the aperture before the band.
We do not confine ourselves to the use of rubber exclusively, as leather, paper, or
any other suitable material may be used.
The advantages of the hereinbefore described method of adapting photographic
shutters to lenses are that a smaller stock of shutters may be kept on hand, as the
various sized lenses may be readily fitted to the standard apertures, instead of having
to fit each shutter to a particular size of lens in the usual way; the user can also.
adjust the opening to fit his lens tightly.
Dated this 11th day of January 1890.

page_text: COMPLETE SPECIFICATION.
Improvements in or connected with Shutters for Photographic
Cameras for Adapting them to Lens Hoods or Mounts of
Different Sizes.
We, JOHN CEDWARD THORNTON, and EDGAR PICKARD, both of St. Mary's Street,
Deansgate, Manchester, in the County of Lancaster, Manufacturers, 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 is designed with the object of providing a suitable packing-which
may be readily inserted and replaced-for adapting photographic shutters that have
openings of any given standard size to lens hoods or mounts of standard sizes less
than the opening in the shutter.
It consists essentially of a packing of rubber or other suitable material formed of
flexible strips of curved shape with a projecting rib at one edge and bevelled or rounded
at the other to be fitted into the opening of the shutter
It will be fully described with reference to the annexed drawings in which :-
Fig. 1. Front elevation of wooden frame of photographic shutter provided with
a packing ring according to this invention.
Fig. 2. Extended view of packing before being inserted in opening of shutter.
Figs. 3. 4 & 5. Tranverse sections on line . . Fig. 1 showing in section three
different sizes or thicknesses of packing.
The shutter A is of any ordinary construction such for instance as that manufactured
by us and described in the Specification of Thornton's Patent No 12238 of 1886 the
operating parts not being shown on the drawings.
The shutter frame or case A is formed with the opening B of any standard size and
the main object we have in view is to make this opening to fit lens hoods or mounts
of smaller size or in other words to alter the size of this opening by the insertion of
a packing provided for the purpose so that it may readily be made to fit any size
of lens.
The packing C, is formed of rubber or other suitable material with one edge-the
edge c which comes to the external side of the shutter-bevelled or rounded and the
other edge cl with a projecting rib.
To cause the packing strip C to hold tightly in the opening B of the shutter when
fitted therein the bevelled or rounded edge c of the packing strip is made longer than
the ribbed edge c¹ so that the packing strip C when extended flat is of the curved
form shown in Fig. 2. Such a strip when made of moderately hard rubber and
sprung edgewise as shown into the opening B in the shutter A. remains tightly in
position without the use of any cement or adhesive material, while at the same time it
may be taken out when desired and replaced with one either thicker or thinner as may
be required to cause the shutter to fit à lens of a different size.
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These packing strips are made of various thicknesses for instance 16, "1" and "
and by the use of these a shutter with a 24" opening may be adapted to fit a 21" lens
as in Fig. 3. a 24" lens as in Fig. 4 or a 23 lens as in Fig. 5.
When the packing strip C is inserted in the shutter opening B the bevelled or
rounded edge c forms a bell-mouthed opening as shown so that the lens hood or
mount may be easily inserted and the rib c forms a stop which prevents it being
pushed in too far.
In addition to the packing C there may be inserted in the side of the shutter frame
or case A to project through into the opening B a small screw D. The end of the
screw D will press behind the rubber packing C and by screwing it in or out the
diameter of the opening B may be diminished or increased. By this means
the opening may be adjusted to fit tightly on to lens hoods or mounts of
irregular or intermediate sizes.
Although we prefer to use the packing C in the form shown in Figs. 2 to 5 it may
be made in two separate pieces one piece to form the packing and the other the rib or

page_text: stop. In this case a ring or washer of the required size would first be inserted in the
opening B to form the requisite rib or stop and then a plain flat piece would be inserted
to receive the lens.
The packing strip C may be made of rubber, cork, wood, leather or any suitable
material though at present we much prefer the indiarubber.
The advantages arising from the invention are that shutters with apertures of standard
sizes may be fitted to lenses of any intermediate size without the necessity of making
shutters specially to fit the intermediate sizes and the user can adjust the opening to
fit the lens tightly or to fit different sizes of lenses.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is
1. A packing for the opening in photographic shutters formed of a flexible curved
strip of rubber or other material having a projecting rib at the concave edge and
bevelled or rounded at the other substantially as and for the purposes described.
2. The combination with the shutter of a photographic camera of a packing strip
of rubber or other flexible material in one or two parts formed with a flat annular
portion to receive the lens hood or mount and a projecting rib or ring against which
it abuts with or without a tightening screw-substantially as and for the purposes
described.
Dated this 26th day of Senten her 1800.
BAY
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.