GB2227104A - Optical system for use with a viewfinder - Google Patents
Optical system for use with a viewfinder Download PDFInfo
- Publication number
- GB2227104A GB2227104A GB9000066A GB9000066A GB2227104A GB 2227104 A GB2227104 A GB 2227104A GB 9000066 A GB9000066 A GB 9000066A GB 9000066 A GB9000066 A GB 9000066A GB 2227104 A GB2227104 A GB 2227104A
- Authority
- GB
- United Kingdom
- Prior art keywords
- denotes
- distance
- ith
- finder
- lens
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/14—Viewfinders
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B19/00—Cameras
- G03B19/02—Still-picture cameras
- G03B19/12—Reflex cameras with single objective and a movable reflector or a partly-transmitting mirror
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Astronomy & Astrophysics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
- Viewfinders (AREA)
Abstract
An optical system for use in with a single lens reflex camera viewfinder having a penta-mirror comprises, from mirror side, a positive first lens element and a negative second lens element satisfying conditions below:- <IMAGE> At least one of the four lens surfaces is preferably aspheric. The lenses may be separate or compound. <IMAGE>
Description
OPTICAL SYSTEM FOR USE WITH A VIEWFINDER MCROUND OF THE INVENTION The present invention relates to an optical system
for use with a viewfinder in single-lens reflex cameras
that employ a penta-mirror in place of a pentaprism.
Prior art optical systems for use with a viewfinder
having a penta-mirror in place of a pentapri.m are
described in Japanese Utility Model Publication Nos. 48
32325 and 48-10424. These prior art optical systems
are advantageous over those which employ a pentaprism in
that they suffer a smaller degree of reduction in - itiagnification. On the other hand, they use so many lens
elements that the overall length of the lenses in the
eyepiece increases, thus making it impossible to realize
a compact camera. Further, the use of expensive glass
results in a higher production cost.
suMMARy OF THE INVENTION
It is an object of the present invention to solve
the above and other problems of the prior art and to
provide an improved optical system for use with a
viewfinder that employs a penta-mirror. The system
adopts a simple two-unit-two-element composition and yet
insures sharp viewing and good performance. Not only is
this optical system compact, but it also achieves high
magnification and can be manufactured at low cost.
The above and other objects of the present
invention are attained by an optical system for use with
a viewfinder in a single-lens reflex camera, which
optical system comprises, in order from the finder
screen side, a first lens unit composed of a positive
lens element and a second lens unit composed of a
negative lens element. This optical system satisfies
the following conditions:
(1) -2 < SF1 < 0
(2) 0 < SF2 < 3 where SF1 is a shape factor of the first lens unit and
SF2 is a shape factor of the second lens unit.
In a preferred embodiment, at least one of the four surfaces delineating said first and second lens units is aspheric.
In another preferred embodiment, the optical system further satisfies the following condition:
(3) 0.05 < (dl + d2 + d3) / f < 0.3 where dl is the thickness of said first lens in the direction of optical axis, d2 is the distance between said first and second lenses on the optical axis, d3 is the thickness of said second lens in the direction of optical axis, and f is the composite focal length of the optical system.
The first lens and second lenses are preferably formed of acrylic resin and polycarbonate resin, respectively, or materials having comparable Abbe numbers.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more clearly understood from the following description in conjunction with the accompanying drawings, wherein:
Figs. 1-12 are simplified cross-sectional views of optical system constructed according to Examples 1-12, respectively; and
Figs. 13-24 are graphs plotting the aberration curves obtained with the optical systems of Examples 112, respectively, when the eye ring has a diameter of 4.
DHwLED DESCRIPTION OF THE PREFKRRHD nBODlXHNTS According to the present invention, the optical system comprises, in order from the finder screen side, a first lens unit composed of a positive lens element and a second lens unit composed of a negative lens element.This optical system satisfies the following conditions:
(1) -2 C SF1 < 0
(2) 0 < SF2 < 3 where SF1 i8 the shape factor of the first lens unit and SF2 is the shape factor of the second lens unit, with the shape factor being given by SF (Rs + Rz)/(Rs - R3), where Rs is the radius of curvature of the surface of each lens on the finder screen side and Rz is the radius of curvature of the surface of each lens on the eyepoint side.
Condition (1) sets forth a requirement that should be satisfied by the shape factor of the first lens unit.
If SF1 is less than the lower limit of this condition, coma can be easily compensated but spherical aberration is difficult to compensate. If SF1 exceeds the upper limit of this condition, spherical aberration can be easily compensated but coma is difficult to compensate.
Further, the distance between the first and second lens units will increase at their marginal areas to cause an undue increase in the effective aperture of the first lens.
Condition (2) sets forth a requirement that should be satisfied by the shape factor SF2 of the second lens unit. If SF2 is less than the lower limit of this condition, coma is difficult to compensate. If SF2 exceeds the upper limit of this condition, the radius of curvature of the surface on the eyepoint side will decrease to produce a virtually short eyepoint.
In order to provide better performance, at least one of the four surfaces delineating the first and second lens units is preferably aspheric. If an aspheric surface is not used, marked coma or changes in eyesight with respect to the center will occur in the marginal area of the visual field. The occurrence of coma is particularly noticeable if the distance between the first and second lens units is increased in order to attain a higher magnification.
In a preferred embodiment, the aspheric surface is preferably of a shape expressed byt
where X is the distance measured from the apex along the optical axis in the direction in which rays travel, Y is the height from the optical axis, R is the radius of curvature of a reference spherical plane, K is the shape factor of a rotating quadratic curved plane, and Au is the asphericity coefficient of a higher degree.
In another preferred embodiment, the optical system further satisfies the following condition.
(3) 0.05 < (d1 + d2 + d3) / f < 0.3 where dl is the thickness of said first lens in the direction of optical axis, d2 is the distance between said first and second lenses on the optical axis, d3 is the thickness of said second lens in the direction of optical axis, and f is the composite focal length of the optical system.
Condition (3) relates to the ratio of the overall length of the optical system to its composite focal length. If the lower limit of this condition is not reached, a desired high magnification is not attainable.
If the upper limit of this condition is exceeded, high magnification is attainable, but the effective aperture of the first lens will become large.
In order to achieve effective compensation for chromatic aberration, it is particularly preferred to make the first lens of an acrylic resin or a crown glass having an Abbe number comparable to that of any acrylic resin, and to make the second lens of a polycarbonate resin or a flint glass having an Abbe number comparable to that of a polycarbonate resin. The use of resin-made lenses offers the added advantage of lighter weight and lower cost.
Examples 1-12 of the present invention are described below with reference to data sheets, in which
SN denotes the surface number, ri denotes the radius of curvature (in millimeters) of the ith surface, di denotes the distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes the refractive index of the jth lens (optical material) at the d-line, vj denotes the
Abbe number of the jth lens (optical material), Ki denotes the shape factor of a rotating quadratic curved plane for the ith surface, A44 denotes the biquadratic asphericity coefficient of the ith surface, and A4i denotes the triquadratic asphericity coefficient of the ith surface. In each of Examples 1-12, the distance from the fourth surface to the eyepoint is 15 mm and the effective finder coverage is 95%. The distance from the screen to the first surface is 81.004 mm for Examples 110, and 74.6 mm for Examples 11 and 12.
EXAMPLE 1
SN ri di nj
1 15.534 6.476 1.49186 57.4 -0.23684 -7.74061xl0-8
2 -28.357 2.154 -7.37018
3 -53.238 1 1.58547 29.9
4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder voverage: 95% f = 70.229 Magnification: 0.740X (52/70.229)
SF1 = -0.292
SF2 w 0.495 (d1+d2+d3) I f = 0.137 EXAMPLE 2
SN ri di nj vj k. m4l 1 14.489 6.224 1.49186 57.4 -0.34447 -7.28882x108
2 -34.501 2.005 -11.6694
3 -146.305 1 1.58547 29.9
4 15
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f - 69.961
Magnification: 0.743X (52/69.961) SFl - -0.408
SF2 = 0.814 (d1+d2+d3) / f = 0.132 EXAMPLE 3
SN ri dj nj vj ki 1 13.231 8.203 1.49186 57.4 -0.275 -1.30316x10-7
2 -24.387 1.231 -9.80573 2.47025x108 3 -110.535 1 1.71736 29.3
4 15
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 67.03
Magnification: 0.776X (52/67.03)
SF1 = -0.297
SF2 = 0.761 (dl+d2+d3) / f = 0.156
EXAMPLE 4
SN r. dj nj vj ki
1 14.678 7.6 1.49186 57.4 -0.38849 -9.08487xl0'
2 -28.267 2.153 -9.04108
3 -333.815 1 1.80518 25.4
4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 67.314
Magnification: 0.772X (52/67.314)
SF1 = -0.316
SF2 = 0.898 (dl+d2+d3) / f = 0.160 EXAMPLE 5
SN ri di flj ki A6i
1 13.944 7.548 1.49186 57.4 -0.43628 -9.2839x10-88
2 -31.306 1.94 -12.3174
3 136.934 1 1.80518 25.4
4 15
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 66.927 Magnification: 0.777X (52/66.927)
SF1 = -0.384
SF2 = 1.246 (d1+d2+d3) I f = 0.157 EXAMPLE 6
SN r dL nj vj ki A6i
1 12.472 7.237 1.49186 57.4 9027 -8.40a78x10'8
2 -69.886 1.944 -53.6169
3 30.528 1 1.80518 25.4
4 11.288
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 65.58
Magnification: 0.793X (52/65.58)
SF1 = -0.697 SF2 = 2.173 (d1+d2+d3) / f = 0.155 EMMXPLE 7
SN ri di nj vJ ki A6i
1 16.589 5.989 1.49186 57.4 -0.88321 -1.00077x10-7 2 -38.051 3.144
3 -142.669 1 1.58547 29.9
4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 70.066
Magnification: 0.742X (52/70.066)
SF1 = -0.393
SF2 = 0.776 (dl+d2+d3) / f = 0.145
EXAMPLE 8 SN r, di nj vj ki
1 15.091 6.814 1.49186 57.4
2 -24.665 1.820 -6.00198 8.98476x10-6 3 -31.262 1 1.58547 29.9
4 20.510
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 70.273
Magnification: 0.740X (52/70.273)
SF1 - -0.241
SF2 = 0.208 (dl+d2+d3) / f = 0.137
EXAMPLE 9
SN ri di nj vj ki
1 13.991 6.168 1.49186 57.4
2 -51.422 2.250
3 -86.065 1 1.5847 29.9 58.9175 -5.27521x105 4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 69.757
Magnification: 0.745X (52/69.757)
SF1 = -0.572
SF2 = 0.654 (dl+d2+d3) / f = 0.135
EXAMPLE 10 SN ri di nj vj kç A6i 1 12.463 6.502 1.49186 57.4
2 -73.265 1.886
3 -60.334 1 1.58547 29.9
4 18.165 4.40044 -4.80934x10-7 Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 68.342
Magnification: 0.761X (52/68.342)
SF1 = -0.709
SF2 = 0.537 (dl+d2+d3) / f = 0.137
EXAMPLE 11
SN ri di nj vj ki A4i
1 12.818 8.5 1.49186 57.4 0.22455 -5.72694x10-6 -8.00138X10-8 2 63.022 0
3 63.022 1.5 1.58547 29.9
4 18 4.08541 -2.U664X10-7
Distance from the screen to the first surface: 74.6
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f r 65 g 211
Magnification: 0.797X (52/65.211)
SF1 = -1.511
SF2 = 1.800 (d1+d2+d3) I f = 0.153 EXAMPLE 12
SN ri di nj vj ki A4i
1 15.175 8.5 1.49186 57.4 0.51174 -6.1107X10-6 -4.61234X10-8 2 737.592 0
3 737.592 1.5 1.58547 29.9
4 25.562 7.51188 -2.60332X10-8
Distance from the screen to the first surface: 74.6
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 68.746
Magnification: 0.756X (52/68.746) SF1 S -1.042
SF2 = 1.072 (dl+d2+d3) / f - 0.145
As described above, the optical system of the present invention adopts a simple two-unit-two-element composition and yet it is capable of achieving higher magnification without using a pentaprism. In spite of its small size, this optical system insures good performance as is clear from the graphs in Figs. 13-24 which plot the aberration curves obtained with this system. If both the first and second lenses are made of resins, the additional advantage of very low cost is attained.
Claims (19)
1. An optical system for use with a viewfinder in a single-lens reflex camera, which optical system has a finder screen side and an eyepoint side and comprises, in order from the finder screen side, a first lens unit comprising a positive lens element and a second lens unit comprising a negative lens element, said optical system satisfying the following conditions:
(1) -2 < SF1 < 0 (2) 0 O < SF2 < 3 where SF1 is the shape factor of the first lens unit,
SF2 is the shape factor of the second lens unit and with the shape factor of each lens unit being defined by:: Rs + R1 SF = - Ra - Rz where Rs is the radius of curvature of the surface of each lens unit on the finder screen side, and R1 is the radius of curvature of the surface of each lens unit on the eyepoint side.
2. An optical system according to claim 1 wherein at least one of the four surfaces delineating said first and second lens units is aspheric.
3. An optical system according to claim 2, wherein said aspheric surface is of a shape expressed by:
where X is a distance measured from an apex along the optical axis in the direction in which rays travel, Y is a height from the optical axis, R is a radius of curvature of a reference spherical plane, K is a shape factor of a rotating quadratic curved plane, and Az is an asphericity coefficient of a higher degree.
4. An optical system according to claim 1, which further satisfies the condition: 0.05 C < (d1 + d2 + d) / f < 0.3 where d1 is the thickness of said first lens unit in the direction of an optical axis of said system, d2is the distance between said first and second lens units on the optical axis, d3 is the thickness of said second lens unit in the direction of said optical axis, and f is the composite focal length of the optical system.
5. An optical system according to claim 2, which further satisfies the condition: 0.05 5 < (d1 + d2 + d3) / f < 0.3 where d1 is the thickness of said first lens unit in the direction of an optical axis of said system, d2is the distance between said first and second lens units on the optical axis, d3 is the thickness of said second lens unit in the direction of said optical axis, and f is the composite focal length of the optical system.
6. An optical system according to claim 1, wherein said first lens is made of an acrylic resin and said second lens made of a polycarbonate resin.
7. An optical system according to claim 1, wherein said first lens unit consists of said first lens element and said second lens unit consists of said second lens element.
8. An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, ri denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a
refractive index of the jth lens (optical material) at
the d-line, vj denotes an Abbe number of the jth lens
(optical material), Rk denotes a shape factor of a
rotating quadratic curved plane for the ith surface, A@i denotes a biquadratic asphericity coefficient of the ith
surface, and A4. denotes a triquadratic asphericity
coefficient of the ith surface, and wherein the distance
from the fourth surface to the eyepoint is 15 mm, the
effective finder coverage is 95% and the distance from
the finder screen to the first surface is 81.004 mmt SN ri di nj vj AEL 1 15.534 6.476 1.49185 57.4 -0.23684 -7.74061x103 2 -28.357 2.154 -7.37018
3 -53.238 1 1.58547 29.
9
4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 70.229 Magnification: 0.740X (52/70.229) SF1 = -0.292
SF2 = 0.495
(d1+d2+d3) / f = 0.137 9.An optical system according to claim 1,
satisfying the following data table, in which SN denotes
a surface number starting from the finder screen side,
ri denotes a radius of curvature (in millimeters) of the
ith surface, di denotes a distance (in millimeters)
between the ith and (i+l)th surfaces, nj denotes a
refractive index of the jth lens (optical material) at::
the d-line, vj denotes an Abbe number of the jth lens
(optical material), Ki denotes a shape factor of a
rotating quadratic curved plane for the ith surface, A* denotes a biquadratic asphericity coefficient of the ith surface, and 244 denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 nun: SN rl di nj wj kZ 1 14.489 6.224 1.49186 57.4 -0.34447 -7.28882x10'8
2 -34.501 2.005 -11.6694 3 -146.305 1 1.58547 29.9
4 15
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 69.961
Magnification: 0.743X (52/69.961) SF1 = -0.408
SF2 = 0.814 (d1+dz+d3) / f = 0.132
10. An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, ri denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), NL denotes a shape factor of a rotating quadratic curved plane for the ith surface, A*1 denotes a biquadratic asphericity coefficient of the ith surface, and A6i denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm: SN ri di nj vj k.
1 13.231 8.203 1.49186 57.4 -0.275 -1.30316x10'7 2 -24.387 1.231 -9.80573 2.47025x1O8 3 -110.535
1 1.71736 29.3
4 15
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 67.03
Magnification: 0.776X (52/67.03)
SF1 = -0.297
SF2 = 0.761 (d1+d2+d3) / f = 0.156
11.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, ri denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, n3 denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), Ki denotes a shape factor of a rotating quadratic curved plane for the ith surface, A44 denotes a biquadratic asphericity coefficient of the ith surface, and A44 denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eye point is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm:
SN r4 di nj vj k4 1 14.678 7.6 1.49186 57.4 -0.38849 -9.C8487x10-8 2 -28.267 2.153 -9.04108 3 -333.815 1 1.80518 25.4
4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f 67.314 Magnification: 0.772X (52/67.314) SF1 = -0.316
SF2 = 0.898 (di+d2+d3) / f = 0.160
12.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, rz denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), K, denotes a shape factor of a rotating quadratic curved plane for the ith surface, AA4 denotes a biquadratic asphericity coefficient of the ith surface, and A4 denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm: SN rZ di nj wj A'L 1
13.944 7.548 1.49186 57.4 -0.43628 -9.28391x10-8
2 -31.306 1.94 -12.3174
3 136.934 1 1.80518 25.4
4 15
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 66.927 Magnification: 0.777X (52/66.927) SF1 = -0.384
SF2 = 1.246 (d1+d2+d3) / f P 0.157 13.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, rt denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), Ri denotes a shape factor of a rotating quadratic curved plane for the ith surface, A4, denotes a biquadratic asphericity coefficient of the ith surface, and A6i denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm:
SN ri di nj vj ki AEL 1 12.472 7.237 1.49186 57.4 -0.49027 -8.40O78x1O8 2 -69.886 1.944 -53.6169
3 30.528 1 1.80518 25.4
4 11.288
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 65.58
Magnification: -0.793X (52/65.58) SF1 a -0.697 SF2 = 2.173 (dl+d2+d3) / f = 0.155
14.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, n3 denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), Ki denotes a shape factor of a rotating quadratic curved plane for the ith surface, Ai denotes a biquadratic asphericity coefficient of the ith surface, and AEL denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm:
SN ri di nj wj k4 1 16.589 5.989 1.49186 57.4 -0.88321 -1.00077x10-7 2 -38.051 3.144
3 -142.669 1 1.58547 29.9
4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f - 70.066
Magnification: 0.742X (52/70.066) SF1 = -0.393
SF2 = 0 . 7 7 6 (d1+d2+d3) / f = 0.145
15.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, r4 denotes a radius of curvature (in millimeters) of the ith surface, dL denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), K, denotes a shape factor of a rotating quadratic curved plane for the ith surface, A44 denotes a biquadratic asphericity coefficient of the ith surface, and A6 denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm: SN ri d nj v3 ki AEL 1 15.091 6.814 1.49186 57.4
2 -24.665 1.820 -6.00198 8.98476x10-6 3 -31.262 1 1.58547 29.9
4 20.510
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 70.273
Magnification: 0.740X (52/70.273) SF1 = -0.241
SF2 = 0.208 (d1+d2+d3) / f = 0.137
16.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), KL denotes a shape factor of a rotating quadratic curved plane for the ith surface, A44 denotes a biquadratic asphericity coefficient of the ith surface, and AEL denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 nun, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm:
SN ri di nJ vj k. AEL 1 13.991 6.168 1.49186 57.4
2 -61.422 2.250
3 -86.065 1 1.58547 29.9 S8.9175 -5.27521x10'5 4 18
Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 958 f = 69.757 Magnification: 0.745X (52/69.757) SF1 - -0.572
SF2 = 0.654 (d1+d2+d3) / f = 0.135
17.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, rl denotes a radius of curvature (in millimeters) of the ith surface, dZ denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, wj denotes an Abbe number of the jth lens (optical material), Ki denotes a shape factor of a rotating quadratic curved plane for the ith surface, A44 denotes a biquadratic asphericity coefficient of the ith surface, and AEL denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 81.004 mm:
SN ri 4 flj v3 ki AEL 1 12.463 6.502 1.49186 57.4
2 -73.265 1.886
3 -60.334 1 1.58547 29.9
4
18.165 4.40044 -4.80934x107 Distance from the screen to the first surface: 81.004
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f - 68.342
Magnification: 0.761X (52/68.342) SF1 = -0.709
SF2 = 0.537 (d1+d2+d3) / f = 0.137
18.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, rt denotes a radius of curvature (in millimeters) of the ith surface, d, denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, Pj denotes an Abbe number of the jth lens (optical material), Ki denotes a shape factor of a rotating quadratic curved plane for the ith surface, A4t denotes a biquadratic asphericity coefficient of the ith surface, and A6i denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 958 and the distance from the finder screen to the first surface is 74.6 mm:
SN ri di nj wj A4i AEL 1 12.818 8.5 1.49186 57.4 0.22455 -5.72694x10-6 -8.00138x108 2 63.022 0
3 63.022 1.5 1.58547 - 29.9
4 18 4.08541 -2.04664X10-7
Distance from the screen to the first surface: 74.6
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f = 65.211
Magnification: 0.797X (52/65.211) SF1 = -1.511 SF2 = 1.800 (d1+d2+d) I f - 0.153
19.An optical system according to claim 1, satisfying the following data table, in which SN denotes a surface number starting from the finder screen side, r4 denotes a radius of curvature (in millimeters) of the ith surface, di denotes a distance (in millimeters) between the ith and (i+l)th surfaces, nj denotes a refractive index of the jth lens (optical material) at the d-line, vj denotes an Abbe number of the jth lens (optical material), Ki denotes a shape factor of a rotating quadratic curved plane for the ith surface, A41 denotes a biquadratic asphericity coefficient of the ith surface, and A6i denotes a triquadratic asphericity coefficient of the ith surface, and wherein the distance from the fourth surface to the eyepoint is 15 mm, the effective finder coverage is 95% and the distance from the finder screen to the first surface is 74.6 mm: SN A6i nj s'j n AEL 1 15.175 8.5 1.49186 57.4 O.S1174 6.7107X10- -4.51234X10-8
2 737.592 0
3 737.592 1.5 1.58547 29.9
4 25.562 7.51188 2.6o332x108
Distance from the screen to the first surface: 74.6
Distance from the fourth surface to the eyepoint: 15
Effective finder coverage: 95% f w 68.746 Magnification: 0.756X (52/68.746) SF1 a -1.042 SF2 = 1.072 (d1+d2+d3) / f = 0.145 20 An optical system for use with a viewfinder in a singlelens reflex camera substantially as herebefore described with reference to any one of examples 1 to 12 or any one of Figures 1 to 24 of the accommanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1002331A JPH0758368B2 (en) | 1989-01-09 | 1989-01-09 | Viewfinder optical system of a single-lens reflex camera using a pentamirror |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9000066D0 GB9000066D0 (en) | 1990-03-07 |
| GB2227104A true GB2227104A (en) | 1990-07-18 |
| GB2227104B GB2227104B (en) | 1993-03-31 |
Family
ID=11526331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9000066A Expired - Fee Related GB2227104B (en) | 1989-01-09 | 1990-01-03 | Viewfinder |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH0758368B2 (en) |
| DE (1) | DE4000448C2 (en) |
| FR (1) | FR2641621B1 (en) |
| GB (1) | GB2227104B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2282460A (en) * | 1991-11-25 | 1995-04-05 | Asahi Optical Co Ltd | Variable power view finder |
| US5410430A (en) * | 1991-11-25 | 1995-04-25 | Asahi Kogaku Kogyo Kabushiki Kaisha | Variable power view finder |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3072157B2 (en) * | 1991-09-10 | 2000-07-31 | 旭光学工業株式会社 | Zoom finder |
| JP4439608B2 (en) * | 1997-12-24 | 2010-03-24 | キヤノン株式会社 | Viewfinder optical system |
| JP6447124B2 (en) * | 2014-12-26 | 2019-01-09 | 株式会社ニコン | Eyepiece, optical device, and method of manufacturing eyepiece |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB983342A (en) * | 1962-12-19 | 1965-02-17 | Ednalite Corp | Improvements in or relating to lens systems |
| GB1269529A (en) * | 1968-06-04 | 1972-04-06 | Ricoh Kk | Improvements in and relating to viewfinder systems |
| GB1483116A (en) * | 1974-10-29 | 1977-08-17 | Rank Organisation Ltd | Optical objectives |
| GB1500495A (en) * | 1975-04-04 | 1978-02-08 | Harwood G | Photographic lens |
| US4212526A (en) * | 1978-08-22 | 1980-07-15 | Minolta Camera Kabushiki Kaisha | Viewfinder for single lens reflex camera |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1800365B2 (en) * | 1968-10-01 | 1976-09-16 | Ausscheidung in: 18 17 991 KJC. Ricoh, Tokio | Lightweight SLR camera - with hollow pentaprism and exposure meter pivotted to swing into operating position after viewing |
| JPS6048013B2 (en) * | 1978-03-09 | 1985-10-24 | キヤノン株式会社 | Finder optical system |
| JPH0241613Y2 (en) * | 1979-02-01 | 1990-11-06 | ||
| JPS5754931A (en) * | 1980-09-19 | 1982-04-01 | Nippon Kogaku Kk <Nikon> | View finder for single-lens reflex camera |
-
1989
- 1989-01-09 JP JP1002331A patent/JPH0758368B2/en not_active Expired - Fee Related
-
1990
- 1990-01-03 GB GB9000066A patent/GB2227104B/en not_active Expired - Fee Related
- 1990-01-09 DE DE19904000448 patent/DE4000448C2/en not_active Expired - Fee Related
- 1990-01-09 FR FR9000180A patent/FR2641621B1/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB983342A (en) * | 1962-12-19 | 1965-02-17 | Ednalite Corp | Improvements in or relating to lens systems |
| GB1269529A (en) * | 1968-06-04 | 1972-04-06 | Ricoh Kk | Improvements in and relating to viewfinder systems |
| GB1483116A (en) * | 1974-10-29 | 1977-08-17 | Rank Organisation Ltd | Optical objectives |
| GB1500495A (en) * | 1975-04-04 | 1978-02-08 | Harwood G | Photographic lens |
| US4212526A (en) * | 1978-08-22 | 1980-07-15 | Minolta Camera Kabushiki Kaisha | Viewfinder for single lens reflex camera |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2282460A (en) * | 1991-11-25 | 1995-04-05 | Asahi Optical Co Ltd | Variable power view finder |
| US5410430A (en) * | 1991-11-25 | 1995-04-25 | Asahi Kogaku Kogyo Kabushiki Kaisha | Variable power view finder |
| GB2261744B (en) * | 1991-11-25 | 1996-07-03 | Asahi Optical Co Ltd | Variable power view finder with aspheric lens surfaces |
| GB2282460B (en) * | 1991-11-25 | 1996-07-03 | Asahi Optical Co Ltd | Variable power view finder |
| US5541768A (en) * | 1991-11-25 | 1996-07-30 | Asahi Kogaku Kogyo Kabushiki Kaisha | Variable power view finder having aspheric lens surfaces |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0758368B2 (en) | 1995-06-21 |
| DE4000448A1 (en) | 1990-07-12 |
| JPH02181713A (en) | 1990-07-16 |
| GB2227104B (en) | 1993-03-31 |
| DE4000448C2 (en) | 1993-12-02 |
| FR2641621A1 (en) | 1990-07-13 |
| GB9000066D0 (en) | 1990-03-07 |
| FR2641621B1 (en) | 1993-04-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101021609B (en) | Zoom lens and camera with zoom lens | |
| US5357374A (en) | Zoom lens system | |
| JPS63155113A (en) | Zoom lens for compact camera | |
| US5136427A (en) | Optical system for use with a viewfinder | |
| JP2900378B2 (en) | Kepler-type zoom finder optical system | |
| CN104880812A (en) | Inner Focus Lens | |
| JPS6361641B2 (en) | ||
| CN102707418A (en) | Zoom lens and camera with zoom lens | |
| CN104508532B (en) | Zoom lens, optical instrument, and method for manufacturing zoom lens | |
| GB2215086A (en) | Zoom lens system for use in a compact camera | |
| CN110873944A (en) | Optical lens | |
| JPS55147606A (en) | Telephoto lens | |
| EP0405856B1 (en) | Zoom lens | |
| GB2371120A (en) | Two group zoom lens with negative front lens group | |
| JP3033276B2 (en) | Wide-angle aspheric zoom lens | |
| KR940000841B1 (en) | Zoom lens | |
| JPH01252915A (en) | Compact high-variable magnification zoom lens system | |
| JPS6344614A (en) | Compact zoom lens for video camera | |
| US4770516A (en) | Telephoto lens system capable of closeup shooting | |
| JPH0460509A (en) | Zoom lens | |
| GB2227104A (en) | Optical system for use with a viewfinder | |
| KR100256203B1 (en) | Super wide angle variable magnification finder | |
| JP2750775B2 (en) | Compact zoom lens | |
| JP2737272B2 (en) | Variable power optical system for infrared | |
| CN213482553U (en) | Zoom lens |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19960103 |