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Патент USA US3074327

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Jan. 22, 1963
A. cox ErAL
3,074,317
ZOOM‘LENS
Filed Deo. 24, 1959
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3 Sheets-Sheet 2
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INVENTORJ'
mfcax
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Jan. 22, 1963
3,074,317
A. COX ETAL
ZOOM LENS
Filed Dec. 24, 1959
5 Sheets-Sheet 5
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INVENTORS'
716.7ïèr' d c/o?zu'on
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United States Patent O "
3,074,317
Patented Jan. 22, 1963
2
1
of FIG.` l to its extreme wide angle position of FIG. 3.
A suitable lens mounting and zooming structure for the
objective disclosed herein is disclosed and claimed in co
pending application Serial No. 854,732, filed November
23, 1959, by F. W. Mellberg and assigned to the common
3,074,317
ZOOM LENS
Arthur Cox, Park Ridge, and Walter J. Johnson, Munde
lein, Ill., assignors to Bell & Howell Company, Chicago,
lll., a corporation of Illinois
assignee.
Filed Dec. 24, 1959, Ser. No. 861,957
2 Claims. (Cl. 88-57)
The front member 1 comprises a front biconvex,
cemented doublet Ll-LZ and a rear singlet L3 predomi
nantly convex forwardly and spaced closely to the doublet
This invention relates to a zoom lens, and more par-.
ticularly to a zoom lens highly corrected over a large 10 L1---L2, and having a dispersive internal contact surface
R2. rIhe mean refractive index of the lens L1 exceeds
range of magnification.
'
that of the lens L2. The linearly movable negative zoomAn object of the invention is to provide a zoom lens
ing member 2 comprises a front negative meniscus singlet
highly corrected over a large range of magnification.
L., convex forwardly and a rear biconcave, cemented
Another object of the invention is to provide an in
expensive zoom lens highly corrected over a magnification 15 doublet component L5-L6 predominantly concave for
wardly. The doublet Lâ--G has a collective internal con
range of at least three to one.
tact surface R9 and the mean refractive index of the lens
It is to be understood that »the terms “front” and
L8 exceeds that of the lens L5. The stationary member
“rear" as herein used refer to the ends of the objective
3 is a positive singlet L», predominantly convex rearward
respectively nearer the long and short conjugates thereof.
In the accompanying drawings froming a part hereof, 20 ly, and forms an afocal lens system with'the members 1
and 2, it being possible 'to use this afocal system as an
FIGS. l to 3 illustrate a zoom lens described herein and
attachment or built in with the prime lens member 4 or
embodying the invention, and respectively show the 0b
with other prime lenses. The prime lens member 4 be
jective in the long, median or intermediate, and short
hind the stop 5 includes a front positive singlet L8 pre
variable equivalent focal length adjustments thereof.
The invention provides a zoom lens or variable equiva
25 dominantly convex forwardly, a biconcave single-t L9 pre
lent focal length objective having a front positive mem
dominantly concave forwardly, a positive meniscus singlet
ber, an intermediate negative member and a rear posi
tive member. The front positive member is movable
L10 concave forwardly and a rear biconvex singlet Lu.
The prime lens shown is va 15.2 mm. f/ 1.8 objective and
is overcorrected to balance out aberrations in the afoeal
non-linearly during zooming yand preferably is adjustable
for focusing also. The intermediate negative member is 30 zooming system, astigmatism primarily being balanced
out, the afocal zooming system being slightly undercor
rected in astigmatism, which undercorrection is uniform
throughout the zooming range. The lenses L1 to L11
movable linearly for zooming, and the rear member is
fixed. Preferably, 'the front member includes a front
positive doublet and a rear positive singlet, the inter
mediate negative member has a front negative meniscus
singlet and a biconcave rear doublet, and the rear mem
have spherical surfaces or radii of curvature R1 to R20,
35 axial thicknesses t1 to tu and axial separations s1 to r9.
The separation S5 of the components L7 and L8 is sufficient
ber comprises a rear prime lens group and a front singlet
to provide clearance for the stop 5 and a known filter
separated by a stop from the prime lens group and form
member (not shown) which may be selectively inserted
ing an afocal system with the front and intermediate
into and removed from the space between the components
members. The afocal system preferably is undercor
rected for astigmatism and the prime lens group is over 40 L7 and L3.
~
The equivalent focal length of the lens described is
corrected for astigmatism to balance out the residual
variable over a three to one range of magnification’ while
astigmatism of the afocal system. ln an alternate em
maintaining a high degree of optical correction for
bodiment, the front member may be movable only for
a large aperture of at least f/ 1.8 throughout the range.
focusing and the rear singlet of the afocal system may be
moved non-linearly for focus compensation during zoom
mg.
Referring now in detail to the drawings, the zoom lens
shown therein includes a front lens member 1, an inter
mediate lens member 2 and a rear lens member made
Spherical aberration, coma, astigmatism, field curvature
and axial and lateral color are highly corrected through
out both the range of focus and the zooming range.
Distortion also is highly corrected but is slightly com
up of a component or member 3 and a prime lens or mem
promised in order to effect `the high degree of correction
of the other aberrations, the distortion being compromised
ber 4 with a stop 5 positioned between the members 3
and 4. The members 3 and 4 are stationary or fixed, and,
at about three and one-half percent in the example shown.
In order to obtain the high corrections and minimize
during zooming, the member 1 is moved non-linearly rela
primary and higher order aberrations, the `afocal posi
tive thereto, first moving to the left from its extreme tele
photo position shown in FIG. l until it reaches the posi
tion thereof shown in FIG. 2, which is the intermediate
tion comprising the members 1, 2 and 3 should be con
structed in substantial compliance with the following in
zooming position of unit magnification, `and then moves
to the right to its extreme wide angle position as shown
in FIG. 3. The member 1 also is adjustable relative to
the members 2, 3 and'4 for focusing for different object 60
distances, `and any focus of the zoom lens for any setting
of the member 1 is correct for all zooming positions.
During zooming, the member 2 is movable linearly rela
tive to the member 1 from its extreme telephoto position
3,074,317
3
_
4
ance out the undercorrection of the afocal zooming sys
tem, and being further characterized in that the zoom
where f1 is the equivalent focal length of the member 1 '
and f2 is the equivalent focal length of the member 2.
A preferred example of the zoom lens having a mag
lens is constructed in substantial compliance with the _
niiication range of three to one is constructed in con
following table in which dimensions are in terms of
formity with the following table wherein dimensions
inches, R1 to R12 designate the respective radii of the
are in terms of inches'and the refractive indices for the
sodium D line and the Abbe dispersion numbers are re
surfaces of the afocal system, t1 to t7 the axial thicknesses,
s1 to s4 the axial separations, nd the indices of dispersion
for the sodium D line, and V the Abbe numbers:
spectively designated at nd and V:
[E.I~`.L. = 1.059 (Fig. 1) Telephoto;
.612 (Fig. 2) Median; .355 (Fig. 3)
'
Wide Angle. f/1.8]
[E.F.L.=l.059 (Teleplloto); .612 (Metliunh .355 (Wide Angle). f/l.8]
,
[B.F.L. = .430]
Li ....... ._
Ri=+4.001
RF1-1.150
L1 ....... _.
lis-12.853
RF1-1.540
L1 ....... -_
[B.F.L.=.43o]
ti=.090
ni=i.720
v=29.3
ti=.300
nd=1.6ii
V=58.8
R1=+4.00i
R1=+1.150
11F-12.853
8i=.005
Ri=+i.540
ti=.2o0
nd=i.6ii
Rs=Plano
V=5s.s
L1 _______ __
_
Rs=-}-3.650
L1 _______ ._
ii=.o65
nd=i.e2o
V=60.3
V=60.3
R7=+.5s5
`n=.095
_
R1=-.7i35
2o L, ....... ._
t1=.060
nd=i.62o
V=60.3
L, _______ _-
:1_-«.145
nd=i.75i
V=27.7
nd=iß20
V=6o.3
ud=i.75i
V=27.7
nd=i.6ii
V=58.s
Rw=+7.500
.
`
e4=.050 (Fig. 1)
Telephoto; ,4_815
(Fig. 2) Median;
.7391 (Fig. 3)
ti=.06o
t1=,145
Ri=+.5s5
Ri=+.585
30
wide Angie
L1 _______ __
Rii=Pl8n0
L: ....... _-
nd=iß2o
(Wide Angle)
s3=.095
11F-.7135
_
V=5s.8
ti=.065
R1=+.5s5
Rio=+4.500
nd=1.6ii
3i=.006
sz=h730>(’1‘ele6
p oto;.48
(Median); .050
Wide Angle
Ri=+3.650
Li._-._-_-_
V=29.3
V=5s.s
c1=.200
20
.051) (Fig. 3)
L1 ....... _.
„F1120
nd=ißii
R5=Plano
siî‘è‘llâû
ep 00;. 11230
(Fig. 2)A Median;
L4 ....... -_
ti=.090
t1=.300
s4=.050 (Tele
oto); .4815
Rii=Plano
(Median): .7301
(Wide Angle)
f1=.09o
Ri:=--1.150
t1=.090
nd=i.61i
v=5s.s
„1:11597
‘1:5112
Riz=-1.l50
R
L! _______ __
390
,8:_125
Rii=P1ano
J _ 080
1115:-,460
Lo ....... ._ R _+ 460
1°", '
L
ia ....... ._
»!s=.280
w+'
_
L1, _______ __ i9=+.¢019
.
Rw=---7019
2. In azoom lens, proceeding from front'to rear, a
front positive member movable non-linearly and includ
‘_’
ing a biconvex front cemented doublet having a disper
ti=.o5o
nd=1.751
V=27-7
sive interna-l contact surface and a rear positive singlet
,7:1112
Rii=--.929
riß-_372
R
'
35
predominantly convex forwardly, an intermediate nega,
_
ziß=.io.->
nd=i.e5i
V=55.s
„1:1620
-
v=60~3
Ss=-007
11,:_120
40 tive zooming member movable linearly relative to the
.
~
front member »and including
a front negative
meniscus
singlet convex forwardly and biconcave rear cemented
‘
doublet predominantly
concave forwardly and having
a
collective internal contact surface, a stationary third posi
45 tive member comprising a positive singlet predominantly
convex rearwardly and forming an afocal lens system
While in the above example, the front member 1 is
with the front and zooming members, and a stationary
moved non-linearly for focus compensation during zoom
rear prime lens includingfa s
and also having a front
ing, it is also contemplated to have the front member 1
positive component, a second iconcave component, a.
stationary during zooming and achieving the focus com
pensation during zooming by moving the lens L1 non 50 third positive meniscus component and a rear biconvex
component, the zoom lens being further characterized in
linearly. The front member 1 preferably would still be
being constructed in substantial compliance with the fol
adjustable for focusing purposes but notduring zoom
lowing -table in which dimensions are in terms of inches,
ing operations.
R1 to R20 designate the radii of curvature of the optical
While the invention is thus described, it is not wished
to be limited to the precise details described, as changes
surfaces, t1 to r11 »the `axial thicknesses, s1 to S8 theaxial
separations, nd the indices of refraction for the sodium
may be readily made without departing from the spirit
D line, and V the Abbe dispersion numbers:
of the invention.
What is claimed is:
l. In a zoom lens, proceeding from front to rear, a
front positive member movable non-linearly and ín 60
cluding a biconvex front cemented doublet having a dis
persive internal contact surface anda rear positive singlet
predominantly convex forwardly, an intermediate nega
tive zooming member movable linearly relative to the
front member and including a front negative meniscus
singlet convex forwardly and a biconcave rear cemented
doublet predominantly concave forwardly and having a
collective internal contact surface, -a stationary third posi
tive member comprising a positive singlet predominantly
convex rearwardly and forming an afocal lens system 70
with the front and zooming members, and a stationary
rear prime lens including a stop wherein the astigmatism '
of the afocal zooming system is undercorrected sub
stantially uniformly throughout the zooming range and
the prime lens is overcorrected for astigmatism to bal 75
1
ß
[E.F.L.=l.059 (Telephoto): .612 (Median): .355 (Wide Angle). f/l.8]
3,074,317
References Cited in the ñle of this patent
UNITED STATES PATENTS
[E.F.L.::1.059 (Telephoto) ; .612 (Median) ; .355 (Wide
[B.F.L. = .43m-Continued
2,847,907
2,937,572
la=.145
a4=.050 (Tele
photo); .4815
(Median) ; .7301
(Wide Angle)
10
nd= 1.697
16
1ld=1.651
nd=1.620
20
Angenieux ........... _- Aug. 19, 1958
Yamaji ______________ -_ May 24, 1960
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