350 and 7 -SR
2,926,564

ORSEARCH ROC,N/March 1, 1960

JIRO MUKAI

2,926,564

HIGH APERTURE WIDE ANGLE OBJECTIVE
Filed July 31, 1957

723 asF. G.

R. R. R. R. Rs R. R. R. R. R. R. R.

F. G. 2-001

OFG. 30.91 mm

SPERICA ABERRATION
DEWATION FROM SNECONDON-001

OFIG. 40.01 mm–20

ASTIGMATIC ABERRATION

02D

DISTORTION

INVENTOR,BY

Jiro Mural

C y ArnoRMey

United States Patent Office
1.

2,926,564
Patented Mar. 1, 1960
2(1) The refractive index on the spectrum d-line of all
positive lenses lies between 1.6 and 1.8;
2,926,564(2)0.034N-NC0.1
HIGH APERTURE WIDE ANGLE OBJECTIVE
N<N<N, 0.07<N-NC0.15
JiroCanon
Mukai,
Kohokuku, Yokohama, Japan, assignor to (3)Camera Company, Inc., Tokyo, Japan, a cor(4)
0.15F<d--d-:0.25
F
poration of Japan
0.05<d--dg0.15 F
0.1 FCds--d--dg0.25 F
Application July 31, 1957, Serial No. 675,354O (5)0.2 FCs.<0.3 F
Claims priority, application Japan October 5, 1956
2 Claims. (C. 88-57)

The present invention relates to a photographic ob 5
jective and more particularly to a high aperture wide
angle objective.
It is an object of the present invention to provide a- high aperture wide angle objective with high efficiency
and high precision.
20
It is another object of the present invention to provide

(6)

(7)

a high aperture wide angle objective having remarkable
The following is an embodiment of the photographic
correction of spherical aberration and other aberrations
objective according to the present invention where thein image curvature and the like.
Other objects and advantages of the present invention 25 focal length is F=1, and the angle of view 2a=63 andwill become apparent from the description hereinafter the aperture ratio is 1:1.4 and the Abbe number of eachfollowing and the drawing forming a part hereof, in lens element is denoted in the order of the alignment byreference symbols vi, via . . . :which:
Fig. 1 shows an illustrative embodiment of the highaperture wide angle objective according to the present 30
R1 =0.689
invention, and
N=1.63980
R1 =0.504
Figs. 2, 3 and 4 are graphs of the sine condition of theN=169100

corrected spherical aberration, astigmatic aberration and

R =2002

distortion, respectively, of said objective.
R =0,385
It is a particular object of the present invention to 35
Ne174400
Rs0.508
provide a high aperture wide angle objective, with an
N=164769
R =0.266
image angle of 63 and an aperture ratio of almost
1:1.4, which has the remarkable advantage of highly
R= -0.369
N=164250
correcting spherical aberration, and other aberrations inR8= -0.254
image curvature and the like, utilizing a new system of 40
Ns
1.59270
R = -3.302
structure and arrangement of newly invented glass in
N=1.71300
photographic objective comprising four components.
R10= -0.545
The high aperture wide angle objective according to theR= -2.149
present invention, of which an illustrative embodiment isNe72000
R= -1.366
shown in Fig. 1, comprises four axially aligned compo 45
nents consisting of eight lenses, the first component I
being positive and comprising negative lens L1 cemented
The graphs of the spherical abberation, sine condition,
to positive lens L, with its cemented surface Ra of con astigmaticaberration, image curvature and distortion inverging power turned convexly towards the object, thesecond component II being of negative power and menis 50 the above embodiment are illustrated in Figs. 2, 3, andcus shape and consisting of positive lens La cemented to 4. In Fig. 2, the heavier chain line SA is the sphericalnegative lens L and having its convex outer surface of aberration graph of the spectrum d-line; the heavier fullradius R towards the object, the third component line SC the graph of the deviation of such d-line fromIII being of negative power and meniscus shaped the sine condition; the fine chain line SA the sphericaland consisting of three lens elements L5, L6, and Li, 55 aberration graph of the spectrum g-line; and the finecemented in the order of positive, negative and posi line SC the deviation graph of such g-line from the sinecondition. . In Fig. 3, the heavy solid line A is the graphtive lens elements with its concave outer surface ofthe sagital field curvature and the broken line Am
radius Rs turned towards the object, and the fourth com of
ponent IV of a bi-convex positive lens La. Denoting the that of the meridional field curvature, while in Fig. 4line D is the graph of the distortion for each angle
overall focal length of the objective by F, the radius of 60 solidof incidence.
curvature of the lens surface of each element in theHeretofore, it has been impossible to attain an aper
order of the alignment by R, R2, ... the refractive
ture ratio beyond f:1.7 for a wide angle objective of anindex on the spectrum d-line of each lens element in the image
angle of 63, since the essential condition to oborder of the alignment by N1, N2, ... the axial thicktain a wider image angle, that is, correction of aberration
ness of the lens element at the optical axis in the order 65 inimage curvature, and another essential condition toof the alignment by d, da . . . , and the axial thickness attainan improvement in photographic power, that is,of the air spacing between adjacent surfaces of eachcorrectionin spherical aberration, naturally conflict withcomponent at the optical axis in the order of the aligneach other in its own structural condition. This is abment by reference symbols S1, S. . . . the high aperture
inevitable so long as the conventional structuralwide angle objective according to the present invention 70 solutely
system and the known glass materials are used. The

satisfies the following conditions:need to overcome this difficulty has been a critical reqr

2,926,564

3
uisite, and the present invention has as a particular

object the elimination thereof by satisfying the conflicting
two essential conditions with the aid of specifically devised glass of low dispersive power and high refractive
index recently introduced, and its overall utilization and 5
intelligently devised structural system corresponding
thereto. In such objective a glass of a low dispersive
power and high refractive index, having a refractive index
between 1.6 and 1.8, is utilized for all positive lens ele
ments thereby to reduce to a minimum the loss entailed O
in other aberrations and thus to improve correction ofspherical aberration. Furthermore, the first component
is composed of two elements of specific shape cemented

2. A high aperture wide angle photographic objective
together, using a negative meniscus lens for its first with improved spherical aberration and curvature ofelement, so that remarkable improvement is attained in 5 image field correction of four axially aligned, air spaced
the desired correction of its image curvature without im components, the first component being of positive power
pairing the correction of spherical aberration. It should and consisting a first negative lens cemented to a first
be noted that in an objective of an aperture ratio of positive lens and convex towards the object side of thearound f:1.4, coma is undeniably aggravated in the gen objective, the second component of negative meniscus
eral case. On the contrary, the objective according to 20 shape and consisting of a second positive lens and a sec
the present invention provides strong converging power ond negative lens cemented to each other and convex
to the radii of curvature of the lens surfaces, R of the to the object side of the objective, the third component
first component and Rs of the third component, as well. being of negative meniscus shape and consisting of aFurthermore, the axial thickness of the air space between third positive, a third negative and a fourth positive interthe Surface of the second component and the adjacent 25 cemented in that order and concave to the object side ofsurface of the third components is given a value between the objective, and a biconvex fourth component, in which
about 0.2 F and 0.3 F so that the aggravation in coma
objective the radii of curvature Rsubscript of the indi
is satisfactorily eliminated. It is another advantage of vidual lens surfaces in succession from the object side
the objective according to the present invention that the 30 of the objective, the distances disubscript at the optical
overall thickness of the whole structure is designed toaxis of the lens thicknesses, the spacings subscript between
the conceivable minimum so that vignetting, prone to
air spaced lens surfaces at the optical axis, the refractive
occur in conventional high aperture wide angle objectives, indices Nsubscript of the d-line, the dispersion factors
is held to a practical minimum.
vsubscript of the individual lenses, the focal length F, andWhat is claimed is:the aperture ratio f, are numerically as follows:35
1. A high aperture wide angle photographic objective
comprising four axially aligned components consisting ofLens
Radius of
Axial
Refractive Dispersion

eight lens elements, a first component of positive power
consisting of two lens elements cemented in the order ofnegative and positive lens elements positioned with its 40

Curvature

Distance

Index

FactorR. s. 0.689

1------------da0.025 N.63980 p34.6
cemented surface of converging power convex towards
the object, a second component of negative meniscus
I""-0.17s. N-loolool -54s
epudiaR2002
shape consisting of two lens elements cemented in theas O.003
order of positive and negative lens elements with its con
R s 0.365
49
vex outer surface towards the object, a third component 45 ------------- Rs a 0.508 dis0.078 Nm.4400
of negative meniscus shape consisting of three lens ele------------d0.025 N164769
33.9
R0.266
ments cemented in the order of positive, negative andas0.257
positive lens elements with its concave outer surface
R = -0.369
LS------------d=0.055
Nas164250
S3.09
towards the object, a fourth component of a bi-convex-0.254
positive lens; the objective satisfying the following con 50 ------------- R.R sursa3.302
dis0.020 Nas1.592.70
35.4
ditions, when the focal length is denoted by F, the radius
L1------------dao.19 Nas171306
sus389of curvature of the surface of each lens element in the
Rio=-0.545
as0.001
order of the alignment by R1, Ra, . . . the refractive
Rs. 2.498------------da0.100 Na2OO
50.3
index on the spectrum d-line of each lens element in theRuut 1.366
order of the alignment by N, N. . . . the thickness ofthe lens element at the optical axis in the order of thealignment by d, d, . . . and the thickness of the air
space between adjacent Surfaces of each component at
References Cited in the file of this patent
the optical axis in the order of the alignment by s,UNITED STATES PATENTS

as . . . . .

1,899,934
2,549,159
2,645,973
2,724,994(1) The refractive index on the spectrum d-line of all

positive lenses is between 1.6 and 1.8;

2,171,640

(2)
(3)
(4)

2,779,239

0.03<N-N30.1
NCNCN0.07<N-NC0.15
0.15 FCd--da0.25F
0.05 FCd--dg0.15F
0.1 FCd--d-dg0.25F

376,044

70 685,572

Berek ----------------- Mar. 7, 1933
Berek ----------------- Sept. 5, 1939
Bertele ---------------- Apr. 17, 1951
Ito -------------------- July 21, 1953
Lange ---------------. Nov. 29, 1955

to ---------------- - Jan. 29, 1957
FOREIGN PATENTS
Great Britain ----------- - July 7, 1932
Germany ------------- Dec. 20, 1939