Improvements in and relating to Photographic Objectives.
Year: 1894

page_text: Date of Application, 13th Oct., 1894-Accepted, 17th Nov., 1894
Improvements in and relating to Photographic Objectives.
I, PAUL RUDOLPH, Doctor of Philosophy of Carl-Zeiss Strasse, Jena in the
Grand Duchy of Saxe-Weimar, German Empire, 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:-
My invention relates to photographic objectives and consists in a quadruple lens
which may be used as a single objective or as a component of a double objective or
doublet. This quadruple lens is distinguished by uniting with a very high
distinctness even of the marginal portions of the image and a great useful angle of
field an exceedingly high rate of the relative intensity of light.
Such result I obtain by cementing together two double lenses or couples of
lenses each of which comprises a collecting lens and a dispersing lens and in one of
which couples the refractive power of the collecting or positive component surmounts
the refractive power of the dispersing or negative component, whilst in the other
double lens the refractive power of the negative leus surmounts that of the positive
lens. In following this principie of construction I may freely select the
dimensions of the single lenses limited only by the kinds of glass, which are at my
disposal, and by the special requirement to be met by the objective, without
substantially altering by any of such combinations of lenses the above stated
optical effects which are united in my quadruple lens.
In consequence of the great variability of shape of the quadruple lens constructed
on my principle, the two component double lenses may both represent positive
systems (ie. systems which are equivalent to collecting lenses) or only one of them
may be positive the other being a negative system (equivalent to a dispersing lens)
even of an infinitely long focal distance. If the quadruple lens is employed as a
component of a double objective, both couples of lenses, of which the quadruple
lens is composed, may form negative systems. Moreover the achromatization of
the quadruple lens may be effected by achromatizing either of both double lenses
or by providing them with contrary chromatic aberrations which compensate one
another. Furthermore both couples of lenses may be associated in any order of
combination, both collecting lenses or both dispersing lenses or the dispersing lens
of the one couple and the collecting lens of the other couple being cemented
together as may be required. Finally the above explained principle of construction
does not prevent the graduation at will of the refractive power of the single lenses
following one another.
As to the double objective, one or both components of which are quadruple lenses
of the described kind, both separate lens systems may be of the same or of different
focal lengths and the focal length of both or only of one may be positive. More-
over either lens system may be for itself completely corrected so as to be occasionally
employed as a single objective or both lens systems may be constructed with
aberrations of about the same amount but in contrary sense, so that the aberrations
of either component compensate one another. If only one component of the double
objective consists of the above described quadruple lens, the other component may
be of any construction, it may consist of only one single lens or of any number of
parts cemented together.
In the annexed drawings three different arrangements of objectives carried out
according to my invention are shown in section.

page_text: Figure 1 represents a quadruple lens, in which the two couples of lenses are
cemented so as to associate the positive components of both couples. The first
couple of lenses consists of a biconcave lens L and a biconvex lens I, the second
couple of a concavo-convex collecting lens L' and of a convexo-concave dispersing
lens Lt.
Fig. 2 represents a quadruple lens, in which the two couples of lenses are
cemented so as to associate the negative components of both couples. The first
couple of lenses consists of a concavo-convex collecting lens L' and of a convexo-
concave dispersing lens L', the second couple of a biconcave lens L³ and of a
biconvex lens L'.
Fig. 3 represents a symmetrical double objective constructed of two equal!
quadruple lenses of the kind represented in Figure 1, the component parts of one
lens being indicated by 1, 2, 3, 4 as in Fig. 1 and the corresponding parts of the
other lens by I, II, III, IV. Both lenses are separately corrected so as to be
capable of being used as single objectives.
In these three figures the line lettered with B represents the plane of the
diaphragın, the letters r², 3, 3, 4, indicate the radii of curvature of the lens-
surfaces and the letters d', ', d³, denote the thicknesses of the single lenses in
the optical axis. The letter b in Figures 1 and 2 and the letters Cand C in
Figure 3 denote the distance of the plane B of the diaphragm from the vertex of
the next lens-surface.
In conclusion I append to this Specification of my invention three examples of
construction, which correspond to the three figures of the drawing. All dimensions
(radii, thicknesses of lenses and distances of the diaphragm) are expressed by
proportional numbers, the focal length of the whole objective being taken as
unity. A simple multiplication of these numbers with the focal length required
in any particular case will suffice for obtaining the dimensions of the objective that
is desired.
The different kinds of glasses are determined by the indices
respectively to the D line of the solar spectrum and to the Hy line of the spectrum
πD and no relating
of hydrogen.

page_text: together of two couples of lenses each of which couples consists of a collecting and
a dispersing lens, the dispersing lens of one couple having a higher refractive
power, and the dispersing lens of the other couple having a lower refractive power
than the collecting lens coupled therewith, substantially as described with reference
to the drawing.
2. A photographic double objective or doublet of which one or both lens systems
consist in a quadruple lens cemented together of two couples of lenses each of
which couples consists of a collecting and a dispersing lens, the dispersing lens of
the one couple having a higher refractive power, and the dispersing lens of the
other couple having a lower refractive power than the collective lens coupled
therewith, substantially as described with reference to the drawing.
Dated the 13th October 1894.
JOHNSONS & WILLCOX,
Agents.