Improvements in Photographic Objectives.
Year: 1889

page_text: Date of Application, 6th July, 1889
Complete Specification Left, 4th Mar., 1890-Accepted, 14th June, 1890
PROVISIONAL SPECIFICATION.
Improvements in Photographic Objectives.
I, Dr. RUDOLF KRÜGENER, of Bockenheim, in the Empire of Germany, do
hereby declare the nature of this invention to be as follows:-
The objectives heretofore used in photography consist almost exclusively of two
halves or parts, each of these halves or parts being made of two lenses (crown glass:
and flint glass), which are cemented together.
The progress made in the science of photography during the last few years has con-
siderably increased the requirements with regard to optical apparatus, whilst by the
momentous undertaking of the Glastechnische Laboratorium at Jena the calculator:
or the designer of optical apparatus has had placed at his disposal kinds of glass.
enabling conditions to be fulfilled which were formerly altogether unknown.
In photographic objectives the aforesaid conditions bear more especially upon the
evenness, and lightness in focal depth of the picture on the plate, as regards the
arrangements of the spherical surfaces.
The present invention is the result of a research which has been carried out with
much labour spent in calculations, and in which many modifications have been taken
into consideration.
In this research it has been found that the circumstances are most favourable if the
front part or system is made of a single flint-glass lens of positive focal length, whilst
the rear part or system, which may be composed in any desired manner annuls the
faults caused by the flint lens in front and together with the former part or system
produces a picture which is planatically and chromatically correct.
As an example may serve an aplanatic device in which the rear part or system
consists of a negative flint glass lens cemented to a positive crown glass lens.
The constants of the same for the following kinds of glass are:-
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Photographic Objectives.
I, Dr. RUDOLF KRÜGENER, of Bockenheim, in the Empire of Germany, 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 state-
ment:-
The objectives heretofore used in photography consist almost exclusively of two

page_text: halves of parts, each of these halves or parts being made of two lenses (crown glass
and flint glass) which are cemented together.
The progress made in the science of photography during the last few years has
considerably increased the requirements with regard to optical apparatus, whilst by
the momentous undertaking of the Glastechnische Laboratorium at Jena the calculator
or the designer of optical apparatus has had placed at his disposal kinds of glass
enabling conditions to be fulfilled which were formerly altogether unknown.
In photographic objectives the aforesaid conditions bear inore especially upon the
évenness and lightness in focal depth of the picture on the plate, as regards the arrange
ments of the spherical surfaces.
The present invention is the result of a research which has been carried out with
much labour spent in calculations, and in which many modifications have been taken
into consideration.
In this research it has been found that the circumstances are most favourable if the
front part or system is made of a single flint-glass lens of positive focal length whilst
the rear part of system, which may be composed in any desired manner annuls the
faults caused by the flint lens in front, and, together with the former part or system
produces a picture which is planatically and chromatically correct.
As an example may serve an aplanatic device in which the rear part or system
consists of a negative flint glass lens cemented to a positive crown glass lens.
The constants of the same for the following kinds of glass are.—
ated this oru day of March 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant..