Year: 1895

page_text: Date of Application, 18th Dec., 1895-Accepted, 22nd Feb.,
1896
We, FRIEDRICH RITTER VON VOIGTLÄNDER, Manufacturer, and Dr. Philosophy
DAVID KAEMPFER Optician both of Brunswick Germany, do hereby declare the
nature of this invention and in what manner the same is to be formed to be
particularly described, and ascertained in and by the following statement :—
This invention relates to photographic objectives which consist of three lenses
cemented together or of two such systems of lenses.
The object of this invertion is to obtain a correction of the spherical aberration
or an increase in the sharpness which is rendered much more perfect, than that of
the objectives hitherto known consisting of lenses cemented together.
And in order to obtain the object in view the invention consists in a photographic
objective which is composed of three meniscuses cemented together, viz. of two
positive and one negative meniscus, the positive one being between the other
positive and the negative meniscus, both the last named meniscuses having a greater
refractive power than the intermediate or enclosed meniscus.
Such a system of lenses can be combined with a second equal, symetetrically or
oppositely placed system or with a second unequal system for the purpose of forming
a double objective.
A double objective consisting of two equal systems of lenses, the one of which
being symmetrical in relation to the other i.e. being the mirror image of the latter,
produces also sharper images than the double objectives hitherto known.
By replacing in this double objective the one system of lenses by another,
consisting of a double convex lens, a double concave lens and an intermediate
positive meniscus, which latter has less refractive power than both the outer lenses,
the advantage is obtained, that this double objective unites in itself the advantages
or preferences of each of the two unequal systems of lenses. The system of lenses,
in which both the outer lenses are respectively double convex and double concave
allows a much more perfect correction of the astigmatism, whereas the other system,
in which the outer lenses are meniscuses, does not allow this perfect avoidance or
suppression of the astigmatism, but allows, as above mentioned, a much more perfect
correction of the spherical aberration.
In the accompanying drawing
Fig. 1 is a double objective, which is composed according to this invention of two
equal, symmetrically placed systems of lenses; and
Fig. 2 is a double objective composed of two unequal systems of lenses.
In Fig. 1 left hand side, a is the intermediate positive meniscus, 6 the one outer
negative meniscus and c the other outer positive meniscus. The meniscuses b and o
have higher refractive power, than the middle meniscus a.
In Fig. 1 right hand side an equal, but symmetrical system of lenses is
represented.

page_text: The component parts of the objective shown in Fig. 1 by way of example are as
follows, if the focal distance is 150 mm and the aperture is 28 mm.
Distance
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is.
1. In a photographic objective the combination of three meniscuses cemented
together the intermediate and one outer one of which are positive, whereas the
other outer meniscus is negative, both the outer ones having greater refractive
power, than the middle one, substantially as and for the purpose described.

page_text: 2. In a photographic objective the combination of two equal, symmetrically
arranged systems of lenses, each consisting of three meniscuses cemented together,
the intermediate and one outer one of which are positive, whereas the other outer
meniscus is negative, both the outer ones having greater refractive power, than the
middle one, substantially as & for the purpose specified.
3. In a photographic objective the combination of a system of lenses, consisting
of three meniscuses cemented together, the intermediate and one outer of which
are positive, whereas the other outer meniscus is negative, both the outer ones
having greater refractive power, than the intermediate one, with another system of
lenses, consisting of a double convex lens, a double concave lens and an intermediate
positive meniscus cemented together, the latter having less refractive power than
both the outer lenses, substantially as and for the purpose specified.
Dated this 18th day of December 1895
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.