AN IMPROVE- MENT IN PHOTOGRAPHIC CAMERAS
Year: 1886

page_text: Date of Application, 4th May, 1886.
Complete Left, 14th Jan., 1887.
Complete Accepted, 15th Feb., 1887.
I, VERO CHARLES DRIFFIELD, Mount Pleasant, Appleton, Widnes, in the County of
Lancaster, Engineer do hereby declare the nature of my invention for AN IMPROVE-
MENT IN PHOTOGRAPHIC CAMERAS to be as follows:-
My invention is applicable to such Photographic Cameras, (generally known as
Detective" Cameras), as consist of two distinct but connected Cameras fitted with
lenses of equal focal length. One of these Cameras is used for focussing the image,
and the other for the exposure of the sensitive plate. My improvement consists in
the application to the focussing Camera of a mirror set at a suitable angle, or of a
reflecting prism whereby the image may be seen from above. The mirror or prism
may be placed behind the usual vertical focussing screen, or a horizontal focussing
screen may be employed if the mirror or prism is placed below the focussing screen.
By this improvement I enable the operator first to support the Camera steadily against
his body during exposure of the plate, and at the same time to see perfectly the
object he is about to photograph, and secondly to secure pictures without attracting
the attention of bystanders or of individuals who may be photographed.
VERO ( DRIFFIELD,
An Improvement in Photographic Cameras.
I, VERO CHARLES DRIFFIELD of Mount Pleasant, Appleton, Widnes, in the County
of Lancaster, Engineer do hereby declare the nature of my invention for AN IMPROVE-
MENT IN PHOTOGRAPHIC CAMERAS and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
My invention is applicable to such Photographic Cameras, (generally known as
Detective Cameras) as consist of two distinct but connected Canieras fitted with
lenses of equal focal length, and which I shall hereinafter call Duplex Cameras. One
[Price 6d.1

page_text: of these Cameras is used for focussing the image, and the other for the exposure of
the sensitive plate.
My improvement consists in the application to the focussing Camera of a mirror set
at a suitable angle, or of a reflecting prism whereby the image may be seen from
above. The mirror or prism may be placed behind the usual vertical focussing
screen, or a horizontal focussing screen may be employed if the mirror or prism is
placed below the focussing screen.
By this improvement I enable the operator first to support the camera steadily
against his hody during exposure of the plate, and at the same time to see perfectly
the object he is about to photograph, and secondly to secure pictures without
attracting the attention of bystanders or of individuals who may be photographed.
The annexed drawing shews two ways of applying my improvement to a duplex
Camera Fig. 1 and Fig. 2 represent each a duplex Camera, the Camera A being used
for focussing the image, and the Camera B for exposing the sensitive plate. Cand C¹
represent the two lenses of equal focal length which are mounted in one frame so as
to move together. D is the front of the Camera which is provided with an aperture
opposite the focussing lens, and what is known as an Instantaneous Shutter
opposite the operating lens. E is the sensitive plate which may be inserted either in
a dark slide, or, in a manner well understood, from an adjustable drawer containing a
number of sensitive plates.
**
The Camera A in Fig. 1 is provided with a focussing screen F which is fixed so that
its ground surface falls in the same vertical plane as the sensitive surface of the
photographic plate. Behind this focussing screen is placed a mirror G set at a
suitable angle, preferably 45 degrees, which mirror is attached to a suitable block H.
This mirror and block are removable for the purpose of cleaning the former. The
image formed upon the focussing screen is reflected upwards by the mirror, and is
viewed through the aperture J.
The Camera Fig. 2 shews another mode of applying my improvement. In this
case the focussing screen F is placed horizontally above the mirror G, and the image
is viewed through the aperture J. It is of course obvious that the optical distance of
the one lens to the focussing screen must be equal to that of the other lens to the
sensitive plate.
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:
The application to duplex Cameras of a plane reflector or mirror for the purpose of
rendering the image visible through an aperture in the upper side of the Camera
substantially as hereinbefore described.
VERO DRIFFIELD.