An Improvement in Photographic Apparatus.
Year: 1893

page_text: Date of Application, 20th May, 1893
Complete Specification Left, 4th Dec., 1893-Accepted, 6th Jan., 1894
PROVISIONAL
SPECIFICATION.
An Improvement in Photographic Apparatus.
I, WILLIAM JOSEPH DIBDIN, of Mayfield, Grange Road, Sutton, in the
County of Surrey, Analytical Chemist, do hereby declare the nature of this inven-
tion to be as follows:-
:-
When photographs are taken from objects brightly reflecting, there is often an
undue difference of the light and shade, giving harsh unbalanced effects, this being
probably owing in many cases to the partial polarisation of many of the rays.
My invention relates to means of avoiding this evil, which I effect by polarising
so as to cut off from the picture more or less of the rays that are partially polarised
by reflection. For this purpose I combine with the lens or lenses of the camera, a
polarising medium, such as a Nicholl's prism, through which all the rays have to
pass on their way to form the image. In order to reduce the magnitude of such
prism, I prefer to place it in or near the place where the rays are most converged.
I mount it in such a way that it can be readily turned and when I form an image
on the screen, I turn it as much as I find necessary to cut off or reduce the
objectionable lights from the picture.
Dated this 20th do...
M1000
ABEL & IMRAY,
Agents for the Applicant.
An Improvement in Photographic Apparatus.
I, WILLIAM JOSEPH DIBDIN, of Mayfield, Grange Road, Sutton, in the
County of Surrey, Analytical Chemist, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement :-
When photographs are taken from objects brightly reflecting, there is often an
undue difference of the light and shade, giving harsh unbalanced effects, this being
probably owing in many cases to the partial polarisation of many of the rays.
My invention relates to means of avoiding this evil, which I effect by polarising
so as to cut off from the picture more or less of the rays that are partially polarised
by reflection. For this purpose, as shewn in section by the accompanying drawing
I combine with the lens or lenses A of the camera a polarising medium, such as a
Nicholl's prism B, through which all the rays have to pass on their way to form
the image. In order to reduce the magnitude of such prism, I prefer to place it,
as shewn, in or near the place where the rays are most converged. I fix it in a
tube C which fits the lens tube D and I fit in a recess E a flange secured to the
tube D so that it can be readily turned and when I form an image on the screen,
I turn it as much as I find necessary to cut off or reduce the objectionable lights
from the picture.
F is the ordinary screen or diaphragm which can be used when the prism B is
removed.
-
Instead of employing a separate lens or separate lenses A, the polarising prism B
might have a lens attached to it on either or on both its sides.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
In combination with the lens or lenses of a photographic camera, a polarising
medium such as a Nicholl's prism, substantially as and for the purpose set forth.
Dated this 4th day of December 1893.
ABEL & IMRAY,
Agents for the Applicant.