Improvements in View Finders for Photographic Cameras or for analogous purposes.
Year: 1898

page_text: PROVAL DI MOLTICATION.
Improvements in View Finders for Photographic Cameras or for
analogous purposes.
We, WALTER MALLETT and WILLIAM WATSON, Opticians, both of 12, Crowland
Road, South Tottenham, London, CHARLES WILLIS BEEVOR, Optician, of 15,
Canning Road, Highbury New Park, London and ARTHUR LEWIS ADAMS, of
26, Charing Cross Road, London, Manufacturer, do hereby declare the nature of
this invention to be as follows:-
This invention relates to improvements in view finders for photographic cameras
or for analogous purposes which will produce a bright non-reversed and clear
image which can be seen (without the necessity of a hood or shading and without
the necessity of ground glass) by the observer when looking into the view finder
at right angles to the view or object that is looking down perpendicularly when the
view finder is held horizontally.
According to the present invention the entering or incident ray passes across
the view finder and meets a silvered or other suitable reflecting surface (down-.
wardly inclined) at the opposite side of the view finder this said silvered or other
suitable reflecting surface (which for the sake of brevity we shall hereinafter refer
to as a No. 1 silvered surface) being so arranged as to bend or direct said ray
downwards where the latter meets a 2nd silvered or other suitable reflecting sur-
face (which for the sake of brevity we shall hereinafter refer to as a No. 2 silvered
surface) by which latter the ray is again bent or directed upwards to the emitting
surface or face the plane of which latter is at or about right angles to the plane of
the aforesaid entering surface while the planes of the aforesaid respective No. 1
and No. 2 silvered surfaces form an acute angle to one another for instance at or
about an angle of 45 degrees to one another.
This view finder may be formed either out of a single body of glass or prism with
the entering and emitting faces at or about right angles to one another as aforesaid
and with the reflecting faces formed opposite thereto as aforesaid and silvered or
having mirrors applied thereto or the reflecting surfaces otherwise formed as
desired.
Or if desired the entering surface may be a concave or other suitable lens at a
suitable distance from the No. 1 reflecting surface disposed opposite to same and
at an angle thereto as aforesaid thus leaving a clear space between the entering lens
and the No. 1 silvered surface and similarly the emitting surface may be a con-
cave or other suitable lens at a suitable distance from the aforesaid No. 2 silvered
surface (the No. 1 and No. 2 silvered surfaces being mounted at an acute angle
with respect to one another as aforesaid) so that a clear space is left between the
No. 2 mirror and the emitting lens but the aforesaid solid glass body or prism
arrangement has certain practical advantages.
A cross or circle or other device or devices may be marked (centrally) on the

page_text: No. 1 silvered surface and similar or other suitable mark provided on the No. 2
silvered surface so that when in use the one mark will appear above the other in
the view finder and when brought into coincidence will be a true indication of the
view being central or in the correct position on the sensitive surface.
It will thus be seen that the entering ray-assuming same to be horizontal-
is bent or directed downwards by the No. 1 mirror and meets No. 2 mirror which
latter directs the ray vertically upwards that is at right angles to its entering line
of entry and consequently such vertical ray traverses its own incident ray without
however same being prejudicially affected thereby.
The entering surface, the two reflecting surfaces, and the emitting surface re-
spectively may be of any suitable formation for instance the entering surface of
the solid glass body or prism arrangement may be concave the two silvered surfaces
flat and the emitting surface concave; or the emitting surface may be flat and the
No. 2 silvered surface concave or all 4 said surfaces may be flat although this
last arrangement is not quite so advantageous.
Or any other desired and suitable arrangement of surfaces concave convex or
plane or any suitable combinations thereof may be used as desired.
1
1000
TONGUE & BIRKBECK,
Southampton Buildings, Chancery, Lane, London, W.C.,
Agents for the Applicants.
Improvements in View Finders for Photographic Cameras or for
analogous purposes.
We, WALTER MALLETT and WILLIAM WATSON, Opticians, both of 12, Crowland
Road, South Tottenham, London, CHARLES WILLIS BEEVOR, Optician, of 15,
Canning Road, Highbury New Park, London, and ARTHUR LEWIS ADAMS, of
26, Charing Cross Road, London, Manufacturer, 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 photographic cameras
or for analogous purposes which will produce a bright non-reversed & clear image
which can be seen (without the necessity of a hood or shading & without the
necessity of ground glass) by the observer when looking into the view finder at
right angles to the view or object-that is looking down perpendicularly when
the view finder is held horizontally.
According to the present invention the entering or incident ray passes across
the view finder & meets a silvered or other suitable reflecting surface (downwardly
inclined) at the opposite side of the view finder this said silvered or other suitable
reflecting surface (which for the sake of brevity we shall hereinafter refer to as
No. 1 silvered surface) being so arranged as to reflect or direct said ray downwards
where the latter meets a 2nd silvered or other suitable reflecting surface (which
for the sake of brevity we shall hereinafter refer to as No. 2 silvered surface) by
which latter the ray is again reflected or directed upwards to the emitting surface or
face the plane of which latter is at or about right angles to the plane of the afore-
said entering surface, while the planes of the aforesaid respective No. 1 & No. 2
silvered surfaces form an acute angle to one another for instance at or about an
angle of 45 degrees to one another.
This view finder is advantageously formed out of a single body of glass or prism

page_text: with the entering & emitting faces at or about right angles to one another as
aforesaid & with the reflecting faces formed opposite thereto as aforesaid said
reflecting surfaces being silvered or having mirrors applied thereto or the reflecting
surfaces otherwise formed as desired.
Or if desired we may construct this view finder in a hollow or skeleton form, the
entering surface may be a concave or other suitable lens at a suitable distance
from the No. 1 reflecting surface disposed opposite to same and at an angle thereto
as aforesaid thus leaving a clear space between the entering lens & the No. 1
silvered surface & similarly the emitting surface may be a concave or other suitable
lens at a suitable distance from the aforesaid No. 2 silvered surface (the No. 1 &
No. 2 silvered surfaces being mounted at an acute angle with respect to one another
as aforesaid) so that a clear space is left between the No. 2 mirror & the emitting
lens-but the aforesaid solid glass body or prism arrangement has certain prac-
tical advantages.
Or if desired the entering & emitting faces & reflecting surfaces may be planes
with a spherical-cylindrical-concave lens used in front of the entering face-
as illustrated in the accompanying drawings.
A cross or circle or other device or devices may be marked (centrally) on the
No. 1 silvered surface & similar or other suitable mark provided on the No. 2
silvered surface so that when in use. the one mark will appear above the other in the
view finder & when brought into coincidence will be a true indication of the view
being central or in the correct position on the sensative surface.
It will thus be seen that the entering ray-assuming same to be horizontal-
is directed downwards by the No. mirror & meets No. 2 mirror which latter
directs the ray vertically upwards that is at right angles to its entering line of
entry & consequently such vertical ray traverses its own incident ray without
however same being prejudicially affected thereby.
The entering surface, the two reflecting surfaces, & the emitting surface re-
spectively may be of any suitable formation for instance the entering surface of
the solid glass body or prism arrangement may be concave the two silvered sur-
faces flat & the emitting surface concave; or the emitting surface may be flat &
the No. 2 silvered surface concave, or all four said surfaces may be flat in which
latter case we find it advantageous to employ a lens in front of the entering face
as illustrated.
Or any other desired & suitable arrangement of surfaces, concave convex or
plane or any suitable combinations thereof may be used as desired.
Referring to the accompanying drawings.
Fig. 1 is a perspective view of the view finder according to our present invention
in its case.
Fig. 2 is a plan view on an enlarged scale.
Fig.
is vertical longitudinal sectional view on line 3-3 Fig. 2.
A is the prism.
Bis spherical-cylindrical-concave lens.
X is case.
a is entering face of prism A.
bis No. 1 reflecting surface-at an angle to said face a.
e is No. 2 reflecting surface at an angle of about 45 degrees to No. 1 reflecting
surface b; & is the emitting surface at an acute angle to the No. 2 surface e, &
at a right angle (or thereabouts) to the entering surface a.
In the case illustrated-all the four said surfaces a, b, c & d are flat surfaces.
The incident ray passing through the lens B is transmitted through the entering
face of the prism & thence to the No. 1 reflecting surface b where same is reflected
downwards & meets the No. 2 reflecting surface c & is there reflected upwards to
the emitting surface d-all as indicated by the arrows 1, 2 & 3 respectively in

page_text: Having now particularly described & ascertained the nature of my said inven-
tion & in what manner the same is to be performed I declare that what I claim is ;-
1. In a view finder, the combination of a silvered surface arranged opposite to
& at an acute angle with the entering lens or surface in suchwise as to direct the
entering or incident ray downwards, a second silvered surface disposed below
said first silvered surface the latter overhanging the second named silvered surface
at such an (acute) angle that the horizontally entering ray, directed diagonally
downwards by the first said silvered surface meets the second said silvered surface
& is thereby reflected vertically upwards to the emitting surface horizontally dis-
posed at an acute angle over the second said silvered surface whereby the ray is
caused to traverse its own incident ray & the image or view is shown in a proper
& non-reversed position substantially as & for the purposes herein before described.
2. A view finder consisting of a solid prism having four faces a, b, c, & d
respectively formed thereon & angularly arranged with respect to one another as
illustrated in the drawings & having the two faces b & silvered & the whole
constructed combined & arranged to operate either with or without a lens such as
B substantially as & for the purposes described & illustrated.
3. The combination in & with a view finder of 2 mirror like surfaces such as b
& c at an acute angle to one another & arranged to act substantially as & for the
purposes herein before set forth.
4. The improved view finder constructed & arranged to act substantially in the
manner & for the purposes herein before set forth.
a
יד
TONGUE & BIRKBECK,
31, Southampton Buildings. Chancery Lane, London, W.C.,
Agents for the Applicants.