Improvements in Photographic View Finders.
Year: 1894

page_text: Date of Application, 8th May, 1894
Complete Specification Left, 8th Feb., 1895--Accepted, 9th Mar., 1895
PROVISIONAL SPECIFICATION.
Improvements in Photographic View Finders.
We HENRY HILL of 151 Fentiman Road, Clapham, London, S.W. Photo-
graphic Apparatus Manufacturer, and ARTHUR LEWIS ADAMS of 81 Aldersgate
Street London E.C. Manufacturer of and Dealer in Photographic Apparatus do
hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in photographic view finders, and has
for its object the better definition or clearer view of the object or objects seen
upon the ground glass or celluloid screen such as is usual in view finders used
upon or in hand or other cameras.
The method of constructing our improved view finder is as follows.―
In front of a mirror of small area (placed at angle of 45° to the axis of the
lens of the camera) we place at half its focal distance a double convex lens of
short focus the axis of this lens being parallel to the axis of the lens of the
camera and then we place a plano-convex lens of short focus and large diameter
joining the upper end of the mirror and subtended over it at an angle of 45° the
whole being enclosed in a case of wood metal or other suitable material to
exclude extraneous light and to get views proportionate to various sized sensitive
plates or films upon a given size plano-convex lens we interpose between the
double convex lens of the finder and the mirror a plano-convex lens of small
diameter and short focus whose axis is coincident with the finder lens.
By these means we are enabled by looking down upon the convex surface of
our plano-convex lens of large diameter to get a perfectly clear and distinct view
and by covering our plano-convex lens of large diameter with a mask of metal
or other suitable material having an opening proportionate to the size of the
plate or film for which the finder is to be used corresponds with that thrown
by the lens of the camera upon the sensitive plate or film in the camera.
Dated this 8th day of May 1894
HENRY HILL.
ARTHUR LEWIS ADAMS.
Improvements in Photographic View Finders.
We, HENRY HILL of 151 Fentiman Road, Clapham, London, S.W. Photo-
graphic Apparatus Manufacturer, and ARTHUR LEWIS ADAMS of 81, Aldersgate
Street, in the City of London, E.C. Manufacturer of and Dealer in Photographic
Apparatus, etc., 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 "view finders" (for use in or on
photographic cameras particularly of the character known as hand cameras) or
instruments by means of which the view-which will be received on the sensitive
surface (plate or film) in the camera when the exposure is made-can be clearly
seen on said "view finder" both before and during the said exposure; a clearer

page_text: and better definition of the view being obtained with our improved “view finder'
than in view finders as heretofore constructed.
A further advantage is that our view finder does not require screening or
shading even from the direct rays of the sun-as our instrument will show the view
clearly defined thereon even with the strongest sunlight on same.
We will now proceed to describe our present invention with reference to the
accompanying sheet of drawings in which same is shown carried out with several
forms of lens or combinations of different lenses.
Figs. 12 and 3 show our view finder with plano-convex lenses throughout-
Fig. 1 being end view, Fig. 2 a plan, and Fig. 3 longitudinal section on lines 1-2
Figs. 1 and 2.
Fig. 4 shows a larger sized view finder with one double convex lens and two
plano-convex lenses.
Fig. 5 shows a still larger view finder having double convex lenses throughout.
Similar letters of reference indicate corresponding parts throughout all the
figures.
a is the front vertical lens or finder lens placed at half its focal length from the
mirror and this view finder is so mounted on the camera that the axis of this
lens will be parallel to the axis of the lens of the camera.
b is top or horizontal lens on or through which the view is depicted.
c is a third lens-interposed between the front lens a and the mirror i-its axis
coinciding with the axis of the finder lens a.
d is the case of any suitable shape-for instance either as shown in Figs. 3 and 4
or that shown in Fig. 5.
e is the top of case-this top or other convenient part of the case being
advantageously so formed and mounted as to be removable or otherwise afford
access to the interior thereof for cleaning or other purposes.
fis aperture in the top e-the size of this opening f being proportionate to the
size of the sensitive surface for which such finder is to be used.
9 g (Fig. 3) are two ribs on the inside of each side wall of the case-to guide
thereinbetween the thin side edges of the lens e or the latter may be mounted or
held in its vertical position in any other suitable manner.
h is a rib or projection on the underside of the top e to keep the lens bin
position or the latter may be mounted and held in position in any other suitable
manner.
i is an ordinary silver-backed mirror-or this latter may be replaced by any
suitable equivalent mirror or reflecting surface.
The mirror i is placed at an angle of 45° (or other suitable angle) to the axis of
the lens of the camera and the said finder lens a respectively.
Taking the case of the view finder illustrated in Fig. 4 :-
The double convex lens a is of short focus and is placed in front of the aforesaid
mirror at (or about) half its focal distance therefrom-the axis of this lens a being
parallel to the axis of the camera lens.
The lens bis plano-convex of short focus and large diameter and is placed
horizontally as shown adjoining the upper edge of said mirror i.
The lens c is also plano-convex of short focus and same diameter (or thereabouts)
to the said lens b and is vertically mounted so that its axis exactly coincides with
the axis of the said lens a-all as shown in Fig. 4.
The position of this lens e relative to the lens a and mirror i is determined by the
proportionate size of view it is desired to show-the relative positions of the lenses
of the particular character and combination shown in Fig. 4 being correct as shown
in this said fig.
In other sizes of view finders or with other characters of lenses-for instance all
three lenses plano-convex as in Fig. 3 or all three lenses double-convex as in
Fig. 5 the distance of lens a from the mirror i will always be half its focal length
(or thereabouts) while to give the exact size of view required to be shown through
the aperture on the case the lens c is placed at a greater or less distance from

page_text: over said mirror i at an angle thereto of 45° or thereabouts and a lens such as c
vertically mounted between the said lens a and said mirror i and having its axis
coinciding with the axis of the said lens a all substantially in the manner and for
the purposes set forth.
6. The improved view finder arranged constructed combined and acting sub-
stantially in the manner and for the purposes hereinbefore described and illustrated
in the drawings hereunto annexed.
.
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicants.