Vibration-isolating optical system

A vibration-isolating optical system having an image stabilizing function, comprising: a fixed lens optical system having a plurality of lens groups which are arranged to be stationary in the vertical direction with respect to the optical axis; and a vibration-isolating compensating optical system disposed adjacently to the image of the fixed lens optical system and arranged to be movable in a direction intersecting the optical axis, wherein the vibration-isolating compensating optical system is constituted by, in sequence order from the portion adjacent to the object, a first factor formed by a double convex positive lens, a second factor formed by a negative lens whose concave confronts the object and a third factor formed by a positive lens, the vibration-isolating compensating optical system being arranged so as to meet the following relationships, assuming that the power (the reciprocal of the focal length) of the overall body of the vibration-isolating compensating optical system is .phi., the power of the first factor is .phi., the power of the first factor is .phi..sub.1, the power of the second factor is .phi..sub.2 and the combination power of the first factor and the second factor is .phi. .sub.12 : .vertline..phi..sub.12 .vertline..ltoreq.0.3 .phi.; -0.5.ltoreq.(.phi./.phi..sub.2)+1.ltoreq.1.0; and -0.3.ltoreq.(.phi..sub.2 /.phi..sub.1)+1.ltoreq.0.3.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a vibration-isolating optical system 
having a so-called vibration isolating function capable of optically 
compensating blurring of a photographed image due to vibrations. More 
particularly, the present invention relates to a vibration-isolating 
optical system capable of compensating image blurring due to the shaking 
of the camera when an image is photographed through the imaging optical 
system and also of compensating image blurring when an image to 
photographed by the imaging optical system loaded on a portion such as an 
automobile or a helicopter which is being vibrated. 
2. Related Background Art 
Hitherto, a system of the type capable of optically compensating image 
blurring has been known as disclosed in (1) Japanese Patent Publication 
No. 56-23125 in which it is employed in an automatic vertical optical 
device. According to this disclosure, the optical axis is vertically 
compensated by causing a prism effect to be changed by relatively rotating 
the positive and negative lenses in an optical system along the 
interacting lens surfaces. Another system has been disclosed in (2) 
Patent Publication No. 41-8558 in which the nodal Japanese point is shifted 
and the image formation point is thereby compensated by causing a portion 
of the lenses in the optical system to be eccentric with respect to the 
optical axis. 
However, the structure disclosed in the above-described Japanese Patent 
Publication (1) encounters a problem in the deterioration in the imaging 
performance because the aberration excessively deteriorates when the 
positive lens and the negative lens have been made eccentric to each other 
and the aberration change is too large to serve as an ordinary imaging 
optical system. As a result, it has not been put into practical use as a 
satisfactory imaging optical system. According to the above-described 
Japanese Patent Publication (2), only the principal structure was 
disclosed and there has not been a description of the aberration 
compensation to be made at the time of compensating the eccentricity. 
Another structure has been disclosed in, for example, Japanese Patent 
Laid-Open No. 63-201623 in which the aberration when the eccentric state 
has been realized is compensated to some extent by using the principle 
disclosed in the above-described Japanese Patent Publication (2). 
However, the structure disclosed in it suffers from a problem in that the 
substantial overall length of the eccentricity-compensating optical system 
is too great and the compensating optical system and that of the holding 
mechanism therefor thereby become too heavy. As a result, the actuator for 
operating the compensating optical system and the holding mechanism 
therefor is heavily loaded. 
SUMMARY OF THE INVENTION 
The present invention has been established so as to overcome the 
above-described problems. Therefore, an object of the present invention is 
to provide a vibration-insulating optical system provided with a 
vibration-insulating compensating optical system capable of extremely 
effectively insulating vibrations only with a reduced size and weight and 
maintaining satisfactory imaging performance in any time before and during 
the compensation of the vibration-insulating compensating optical system. 
In order to achieve the above-described object, according to the present 
invention, there is provided a vibration-isolating optical system 
comprising: a fixed lens optical system having a plurality of lens groups 
which are arranged to be stationary in the vertical direction with respect 
to the optical axis; and a vibration-isolating compensating optical system 
disposed adjacently to the image of the fixed lens optical system and 
arranged to be movable perpendicularly to the optical axis, wherein the 
vibration-isolating compensating optical system is constituted by, in 
sequence order from the portion adjacent to the object, a first factor 
formed by a double convex positive lens, a second factor formed by a 
negative lens whose concave confronts the object and a third factor formed 
by a positive lens, the vibration-isolating compensating optical system 
being arranged so as to meet the following relationships, assuming that 
the power (the reciprocal of the focal length) of the overall body of the 
vibration-isolating compensating optical system is .phi., the power of the 
first factor is .phi..sub.1, the power of the second factor is .phi..sub.2 
and the combination power of the first factor and the second factor is 
.phi..sub.12 : 
##EQU1## 
In the above-described case in which "the vibration-insulating compensating 
optical system is movable perpendicularly to the optical axis" includes 
not only a case where the vibration-insulating compensating optical system 
is made eccentric vertically (so-called shifted) with maintaining the 
parallel relationship between the optical axis of the vibration-insulating 
compensating optical system and the optical axis of the overall body of 
the vibration-insulating optical system including the fixed lens group, 
but also a case in which it is made eccentric in such a manner that the 
optical axis of its vibration-insulating compensating optical system is 
tilted with respect to the overall body of the vibration-insulating 
optical system. 
It is preferable that the luminous flux made incident upon the 
vibration-insulating compensating optical system be substantial parallel 
luminous flux. In order to realize this, it is preferable that the fixed 
lens group disposed adjacent to the object in the vibration-insulating 
compensating optical system and stationary in the direction perpendicular 
to the optical axis forms a substantial afocal system. 
According to the present invention, there is provided a 
vibration-insulating compensating optical system capable of maintaining 
satisfactory imaging performance in any time before and during the 
compensation of the vibration-insulating compensating optical system only 
with a reduced size and weight. Since the vibration-insulating 
compensating optical system can be reduced in size and weight with respect 
to the overall body of the imaging optical system, the load of the 
operation device for the vibration-insulating compensating optical system 
can be reduced. Furthermore, it can be formed as so-called a tacking 
device capable of always framing a specific subject to a predetermined 
position. 
Other and further objects, features and advantages of the invention will be 
appear more fully from the following description made with reference to 
the drawings

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will now be described in 
detail with reference to the drawings. 
Each of the embodiments comprises, in sequence order from the portion 
adjacent to the object, a lens group GF which is arranged to be stationary 
in the vertical direction with respect to the optical axis, and a 
vibration-isolating compensating optical system Gv arranged to be movable 
perpendicularly to the optical axis. The vibration-isolating compensating 
optical system Gv is constituted by, in sequence order from the portion 
adjacent to the object, a first factor L.sub.1 formed by a double convex 
positive lens, a second factor L.sub.2 formed by a negative lens whose 
concave confronts the object and a third factor L.sub.3 formed by a single 
positive lens or a combination or a laminated positive lens of a negative 
lens and a positive lens. The vibration-isolating compensating optical 
system is arranged so as to meet the following relationships, assuming 
that the power (the reciprocal of the focal length) of the overall body of 
the vibration-isolating compensating optical system is .phi., the power of 
the first factor is .phi..sub.1 : the power of the second factor is 
.phi..sub.2 and the combination of the power of the first factor and the 
second factor is .phi..sub.12 : 
##EQU2## 
In this state, the vibration-insulating compensating optical system Gv may 
be moved in such a manner that the optical axis of the 
vibration-insulating compensating optical system Gv is made eccentric (a 
so-called "shift") in parallel to the optical axis of the overall body of 
the vibration-insulating optical system including the fixed lens group GF. 
Alternatively, it may be eccentrically moved (a so-called "tilted") in 
such a manner that the optical axis of the vibration-insulating 
compensating optical system Gv is tilted with respect to the optical axis 
of the overall body of the vibration-insulating optical system. It is 
preferable that the luminous flux to be made incident upon the 
vibration-insulating compensating optical system Gv be made substantially 
parallel flux. In order to realize this, it is preferable that the fixed 
lens group GF be arranged to be a substantially afocal optical system. In 
the case where the vibration-insulating compensating optical system Gv is 
not made eccentric, it is effective to compensate the aberration generated 
in the vibration-insulating compensating optical system Gf is compensated 
in the forward fixed lens group GF so as to satisfactorily compensate the 
aberration as the overall body of the optical system. The reason for this 
lies in that the fixed lens group GF adjacent to the object and the 
vibration-insulating compensating optical system Gv are disposed coaxially 
to each other and it cannot thereby be moved perpendicularly to the 
optical axis. The vibration-insulating optical system of a type according 
to the present invention is constituted in such a manner that the optical 
axis of the fixed lens group GF positioned adjacent to the object and that 
of the rearward vibration-insulating compensating optical system Gv are 
made coaxial at the time of the ordinary photographing However, the 
vibration-insulating compensating optical system Gv is made eccentric with 
respect to the optical axis of the vibration-insulating optical system by 
being vertical moved or rotary moved when the image blurring is 
compensated Taking this state into consideration, the balance established 
between the fixed lens group GF and the vibration-insulating compensating 
optical system Gv is caused to be lost significantly. Therefore, the 
obtainable aberration as the overall body of the optical system becomes 
insufficient. Therefore, the fixed lens group GF adjacent to the object 
and the vibration-insulating compensating optical system Gv must be 
independently aberration-compensated in order to reduce the aberration 
change due to the eccentricity compensation operation by eliminating the 
aberration dependency between the fixed lens group GF and the 
vibration-insulating compensating optical system Gv. 
Therefore, according to the present invention, the vibration-insulating 
compensating optical system Gv is constituted by, in sequence order from 
the portion adjacent to the object, a first factor L.sub.1 formed by a 
double convex positive lens, a second factor L.sub.2 formed by a negative 
lens whose concave confronts the object and a positive lens third factor 
L.sub.3 formed by a single lens or a combination of a positive lens and a 
negative lens As a result, the aberration compensation operation of the 
vibration-insulating compensating optical system can be extremely 
satisfactorily performed and its size can be reduced significantly. That 
is, assuming that light made incident, in parallel to the optical axis, 
upon the lens surface adjacent to the object is called "Rand light", the 
Rand light made incident upon the first factor L.sub.1 of the 
vibration-insulating compensating optical system Gv is made substantially 
run parallel to the optical axis since the fixed lens group GF of the 
forward optical system is arranged to be substantially an afocal system. 
Therefore, the shape of the first factor L.sub.1 must be in the form of a 
double convex shape because there is a necessity for the shape so as not 
to be considerably different from the shape which makes the minimal 
deflection angle to the Rand light considering the lens is a set of small 
prisms. It is most effective to compensate the aberration generated in the 
first factor L.sub.1 of the positive lens by arranging the negative lens 
serving as the second factor L.sub.2 to be positioned next to the first 
factor L.sub.1 of the positive lens. 
Since the overall body of the vibration-isolating compensating optical 
system Gv is arranged to be a positive lens group, it is therefore 
necessary for the structure to be arranged in such a manner that the 
largest number of lenses have positive power in order to prevent 
generation of the positive higher aberration factor from the 
vibration-isolating compensating optical system Gv. A structure arranged 
in such a manner that the third factor L.sub.3 is constituted by a 
negative lens and a positive lens as an alternative to the sole positive 
lens will cause the vibration compensating optical system Gv to 
satisfactorily compensate various aberrations with a reduced size 
maintained. 
In particular, the structure must be arranged in such a manner that the 
combined power .phi..sub.12 of the first component factor L.sub.1 and that 
of the second factor L.sub.2 are arranged to meet the relationship 
expressed by the above-described Inequality (1). Inequality (1) expresses 
a fact that the power of the absolute value .phi..sub.12 is smaller than 
that of the overall body of the vibration-isolating compensating optical 
system Gv. That is, a fact is shown that the power distribution of the 
vibration-isolating compensating optical system Gv is arranged in such a 
manner that the absolute value of the power of the third factor L.sub.3 is 
sufficiently larger than the combined power .phi..sub.12 of the power of 
the first factor L.sub.1 and that of the second factor L.sub.2. Therefore, 
a large portion of the overall power is distributed to the third factor 
L.sub.3 and the non-axial aberration generated in the third factor L.sub.3 
can be compensated by a pair consisting of the first factor L.sub.1 and 
the second factor L.sub.2 each of which has small power. The reason for 
this lies in that the third factor L.sub.3 having large power contributes 
to the aberration of the Rand light, while the first factor L.sub.1 and 
the second factor L.sub.2 each of which has small power considerably 
contribute to the non-axial aberration. Similarly, the aberration change 
of the non-axial light due to the lens group of the third factor L.sub.3 
caused from the eccentricity compensation can be satisfactorily 
compensated by the first factor L.sub.1 and the second factor L.sub.2. 
Furthermore, since the combined power of the first factor L.sub.1 and the 
second factor L.sub.2 is power of a relatively low level, width D.sub.2 of 
the air layer between the second factor L.sub.2 and the third factor 
L.sub.3 can be relatively freely arranged. Therefore, the overall length 
of the vibration-isolating compensating optical system Gv can be shortened 
by reducing the width D.sub.2 of the air layer. Furthermore, since the 
divergence effect is a relatively low level even if the combination of the 
first factor L.sub.1 and the second factor L.sub.2 is negative power and 
since the width D.sub.2 of the air layer is a small value, the effective 
diameter of the third factor L.sub.3 can be made a similar diameter as 
that of the factor L.sub.1 and that of the second factor L.sub.2. 
Therefore, it is necessary for the power of the first factor L.sub.1 and 
that of the second factor L.sub.2 to be reduced in the region which meets 
Inequality (1). As described above, the aberration change at the time of 
the eccentricity compensation can be controlled and the size of the 
vibration-insulating compensating optical system Gv can be reduced by 
arranging the power distribution of the vibration-insulating compensating 
optical system Gv to meet Inequality (1). 
Then, the conditions for the above-described Inequalities (2) and (3) 
relating to the power .phi. of the overall body of the 
vibration-insulating compensating optical system Gv, power .phi..sub.1 of 
the first factor L.sub.1 and the power .phi..sub.2 of the second factor 
L.sub.2 will be described. Inequality (2) shows a proper range for 
.phi..sub.2 with respect to .phi. for the purpose of compensating the 
aberration of the positive lens generated in the third factor L.sub.3, the 
aberration being compensated by the negative lens of the second factor 
L.sub.2. If the power .phi..sub.2 exceeds the upper limit of Inequality 
(2), the aberration is excessively compensated by the lens having negative 
power, causing a necessity of a lens factor to be provided for the purpose 
of compensating the excessive aberration compensation. As a result, the 
structure of the vibration-insulating compensating optical system Gv 
cannot be simplified. If the power .phi..sub.2 is lowered below the lower 
limit shown in Inequality (2), the aberration compensation performed by 
the lens having negative power becomes insufficient. Therefore, an 
additional lens having negative power must be provided for the purpose of 
compensating the lacking for the aberration compensation. As a result, it 
is difficult to simplify the structure of the vibration-insulating 
compensating optical system Gv. 
Inequality (3) shows the relationship between the power of the first factor 
L.sub.1 and that of the second factor L.sub.2 in the power distribution 
determined in accordance with Inequalities (1) and (2). Since the first 
factor L.sub.1 and the second factor L.sub.2 are combined with each other 
and form an optical system approximating to an afocal system, Inequality 
(3) means the afocal magnification realized by the first factor L.sub.1 
and the second factor L.sub.2 is made approximate to -1 considering that 
.phi..sub.2 /.phi..sub.1 is an afocal magnification, where a fact that the 
value is lowered below the lower limit shown in Inequality (3) represents 
a fact that the afocal magnification exceeds -1.3. This means a fact that 
.phi..sub.1 is made smaller than .vertline..phi..sub.2 .vertline.. 
Therefore, when the first factor L.sub.1 and the second factor L.sub.2 are 
arranged to be a system approximating to an afocal system, the distance 
between the principal point of the first factor L.sub.1 and that of the 
second factor L.sub.2 is widened. As a result, the overall length of the 
combined system of the first factor L.sub.1 and the second factor L.sub.2 
is inevitably lengthened. Therefore, the size of the structure cannot be 
reduced. On the other hand, a fact that the value exceeds the upper limit 
shown in Inequality (3) represents a fact that the afocal magnification is 
lowered below -1.3. Accordingly, the third factor L.sub.3 must have power 
1.43 times or more the power of the overall body of the 
vibration-insulating compensating optical system Gv. Therefore, the 
structure of the third factor L.sub.3 cannot be reduced. 
It is preferable that the power distribution for each of the factors be 
arranged in such a manner that the width D.sub.2 of the air layer between 
the second factor L.sub.2 and the third factor L.sub.3 meets the following 
relationship: 
EQU 0.ltoreq..phi..multidot.D.sub.2 .ltoreq.0.1 (4) 
As a result, as in the description made about the conditions for Inequality 
(1), the length of the vibration-insulating compensating optical system Gv 
can be shortened, and the overall size can thereby be reduced. That is, if 
the value exceeds the upper limit shown in Inequality (4), the distance 
between the second factor L.sub.2 and the third factor L.sub.3 becomes too 
large, causing the overall length of the vibration-insulating compensating 
optical system Gv to be made too large. As a result, the weight of the 
mechanism for holding the vibration-insulating compensating optical system 
is made too heavy, causing the actuator is loaded heavily. Therefore, the 
aberration compensation cannot be performed quickly. 
It is preferable that the structure according to the present invention be 
arranged in such a manner that the shape of the negative lens serving as 
the second factor L.sub.2 is arranged such that the form factor q.sub.2 
meets the following relationship: 
EQU 0.6&lt;q.sub.2 &lt;6 (5) 
Assuming that the curvature radius of the surface of the lens factor 
confronting the object is ra and the curvature radius of it confronting 
the image is rb, the form factor q is expressed by: 
EQU q=(rb+ra) / (rb-ra) 
The principal point of the second factor L.sub.2 can be approached to the 
principal point of the first factor L.sub.1 positioned in the lens of the 
first factor L.sub.1 by arranging the shape of the second factor L.sub.2 
from a negative meniscus shape whose concave confronting the object to a 
double concave approximated to a plane concave. Therefore, a substantially 
afocal small size optical system formed by combining the first factor 
L.sub.1 and the second factor L.sub.2 can be constituted. If the value is 
lowered below the lower limit shown in Inequality (5), the compensation of 
the non-axial aberration of the third factor L.sub.3 by the first factor 
L.sub.1 and the second factor L.sub.2 becomes insufficient. In particular, 
the upper comatic aberration is reduced to an excessively large negative 
value. As a result, asymmetry is inevitably made excessive. In order to 
satisfactorily reduce the distance between the principal point of the 
first factor L.sub.1 and that of the second factor L.sub.2 so as to reduce 
the size, it is preferable that the lower limit of the above-described 
condition be 1. 
In the case where the value exceeds the upper limit shown in Inequality 
(5), the degree of bending of the second factor L.sub.2 is made too large. 
As a result, the compensation of the aberration of the third factor 
L.sub.3 is performed excessively. In particular, the degree of astigmatism 
is inevitably made an excessive positive value. Furthermore, higher 
aberration is excessively generated, and the aberration compensation 
cannot be maintained in a satisfactory state. 
Assuming that the curvature radius of the surface of the third factor 
L.sub.3 serving as the final component of the vibration insulating 
compensating optical system Gv which is nearest to the object is R.sub.l, 
it is preferable that the following relationship be held: 
##EQU3## 
The Inequality (6) shows the relationship between the combined power 
.phi..sub.12 of the first factor L.sub.1 and the second factor L.sub.2 and 
R.sub.l. Since, the third factor L.sub.3 mainly contributes to the 
aberration of the Rand light, the shape of plane S.sub.1 must be arranged 
so as to reduce the aberration of the Rand light generated in the third 
factor L.sub.3 depending upon the incidental angle (divergent light or 
convergent light) of light made incident upon the third factor L.sub.3. 
Therefore, in the case where the incidental light upon the third factor 
L.sub.3 is divergent light, the plane S.sub.1 must be, in principle, a 
concave or a plane approximated to a plane in order to bent the light at 
an angle approximated to the minimal deflection angle when it is provided 
that the lens is a set of small prisms. 
In the contrary case in which the incidental light upon the third factor 
L.sub.3 is convergent light, the shape must be a convex confronting the 
object or a plane approximated to a plane. If the plane S.sub.1 is not 
arranged to be a plane with which light is refracted at an angle near the 
minimal deflection angle, it is difficult to reduce the aberration of the 
Rand light generated in the third factor L.sub.3. Therefore, it is 
difficult to simplify the structure of the third factor L.sub.3 and to 
simultaneously reduce the aberration change due to the eccentricity. 
The lower limit of Inequality (6) lies in the direction in which R.sub.l 
and .phi..sub.12 have different signs and R.sub.l increases, that is, the 
direction in which the incidental angle of the Rand light upon the third 
factor L.sub.3 becomes enlarged and the generation of aberration is 
enlarged. Therefore, if the value is lower than the lower limit shown in 
Inequality (6), the aberration of the Rand light tends to be enlarged. As 
a result, the aberration compensation by the vibration-insulating 
compensation optical system Gv cannot be satisfactorily conducted with the 
number of the lenses forming the third factor L.sub.3 reduced 
simultaneously. If the value exceeds the upper limit shown in Inequality 
(6), the comatic aberration can be generated or astigmatism or comatic 
aberration can be generated when the eccentric state has been realized. 
In the case where the third factor L.sub.3 is formed by only one positive 
lens, the vibration-isolating compensating optical system Gv is formed by 
only three lenses. Assuming that the refractive index of the second factor 
L.sub.2 and that of the third factor L.sub.3 are respectively N.sub.2 and 
N.sub.3, and the abbe's number of the first factor L.sub.1 and that of the 
second factor L.sub.2 are respectively .nu..sub.1 and .nu..sub.2, it is 
preferable that the following relationship be held: 
##EQU4## 
In order to compensate chromatic aberration, it is preferable that the 
first factor L.sub.1 employs a low divergent glass and the second factor 
L.sub.2 employs a high divergent glass since the vibration-isolating 
compensating optical system Gv can be simply structured by three sections. 
Specifically, since the power of the third factor L.sub.3 is the main 
portion of the power of the overall body of the vibration-insulating 
compensating optical system Gv, the curvature radius of the lens of the 
third factor L.sub.3 tends to be reduced. In order to reduce the higher 
aberration generated in the third factor L.sub.3, it is preferable that 
the structure is formed by moderate curved surfaces with arranging the 
refraction index N.sub.3 of the third factor L.sub.3 to be 1.71 or more so 
as to meet the conditions shown in Inequality (8). However, if the 
refraction index of the positive lens serving as the third factor L.sub.3 
is raised, the Petzval's sum is made a large negative value. Therefore, it 
is preferable that the refraction index N.sub.2 of the second factor 
L.sub.2 be 1.75 or more, so that the Petzval's sum is compensated to a 
certain positive value. 
In order to obtain further improved aberration, it is preferable that the 
combined power .phi..sub.12 of the first factor L.sub.1 and the second 
factor L.sub.2 be a negative value, that is .phi..sub.12 .ltoreq.0. 
Therefore, an excellent aberration balance can be established with the 
third factor L.sub.3 formed only one positive lens by causing aberration 
to be generated as a negative lens system by the first factor L.sub.1 and 
the second factor L.sub.2 of the vibration-isolating compensating optical 
system Gv. 
In the case where the third factor L.sub.3 is formed by two lenses: a 
negative lens L.sub.31 and a positive lens L.sub.32, it is preferable that 
the negative lens be positioned adjacent to the object, while the positive 
lens be positioned adjacent to the image. The reason for this lies in that 
the characteristic of the spherical aberration of the structure formed by 
the first factor L.sub.1 and the second factor L.sub.2 to become a 
negative value is cancelled by the characteristic of the third factor 
L.sub.3 to become a positive value in which the concave and the convex are 
arranged in this order, the structure formed by the first factor L.sub.1 
and the second factor L.sub.2 being structured by arranging a convex and a 
concave in this order. In order to obtain further improved aberration, it 
is preferable that the negative lens L.sub.31 in the third factor L.sub.3 
be a concave confronting the image and the positive lens L.sub.32 in the 
third factor L.sub.3 be a convex confronting the object. Thus, the upper 
comatic aberration which tends to become a negative value on the lens 
surface of the negative lens L.sub.31 of the third factor L.sub.3 adjacent 
to the image can be compensated toward the positive direction. 
Furthermore, the tendency of the aberration of the Rand light to become a 
positive value in this case is compensated by arranging the lens surface 
of the positive lens L.sub.32 disposed next to be a convex confronting the 
object. When the negative lens L.sub.31 and the positive lens L.sub.32 of 
the third factor L.sub.3 are laminated to each other, generation of 
asymmetric aberration due to the vibrations caused from the compensation 
of the eccentricity can be reduced. Therefore, the aberration change of 
the third factor L.sub.3 due to the vibrations, that is, the eccentricity 
can be further reduced. 
The compensation of image blurring by the vibration-insulating compensating 
optical system is applied to the overall image plane. Therefore, although 
the image blurring can be compensated at the central portion of the image 
plane by a single lens, the peripheral portion of the image blurring 
cannot be sufficiently compensated because aberration is generated due to 
the vibration-insulating compensation operation. Therefore, the 
vibration-insulating compensating optical system Gv must be formed by at 
least a positive lens and at least a negative lens so as to cause the 
aberration generated in the positive lens to be compensated by the 
negative lens. 
In the case where the eccentricity of the vibration-insulating compensating 
optical system Gv at the time of compensating image blurring is realized 
by rotationally tilting the optical axis of the vibration-insulating 
compensating optical system Gv with respect to the coaxial optical axis of 
the vibration-insulating optical system, the center of rotation must be 
rotationally tilted relative to at least a point on the coaxial optical 
axis of the vibration-insulating optical system which is brought to a 
stationary state. If the center of rotation is positioned outside the 
coaxial optical axis of the vibration-insulating optical system, the locus 
of the movement of the vibration-insulating compensating optical system Gv 
for compensating image blurring can be made symmetric with respect to the 
optical axis. Therefore, the structure for the mechanical control becomes 
too complicated. In the structure in which the number of the center of 
rotation is arranged to be one, the vibration-insulating compensating 
optical system Gv describes only a circular locus which is symmetric with 
respect to the optical axis. However, when the structure is arranged in 
such a manner that the center of rotation can move to a plurality of 
points on the coaxial optical axis, design of the optical structure can be 
conducted further freely. 
Assuming that the center of rotation of the vibration-insulating optical 
system on the coaxial optical axis is P, the distance from the rotation 
center P to the position of the rear principal point of the vibration 
insulating compensating optical system Gv is Lp, the overall length of the 
vibration-insulating compensating optical system Gv is l and the maximum 
vibration insulating compensated quantity on the image surface is 
.DELTA.y, it is preferable that the distance Lp meets the following 
relationship: 
EQU .vertline.Lp.vertline.&gt;.vertline..DELTA.y.vertline..multidot.l(9) 
If the position of the rotation center P, that is the distance from the 
rotation center P to the rear principal point of the vibration-insulating 
compensating optical system Gv deviates from the above-described 
relationship (9), the rotational tilting angle on the image plane with 
respect to the maximal vibration-insulating compensating quantity .DELTA.y 
becomes too large. Because of an additional reason that the 
vibration-insulating compensating optical system Gv is formed in a thick 
structure, the optical path in the vibration-insulating optical system Gv 
changes significantly from the optical path in the state in which the 
vibration-insulating compensation has not been performed as yet. As a 
result, the more the view angle becomes, the more the aberration at the 
stationary state and the aberration at the time of vibration-insulating 
compensation excessively differ from each other. Therefore, it is 
preferable that the position of the rotation center P meets Inequality 
(9). 
In particularly, in order to effectively perform the vibration-insulating 
compensation, it is preferable that the position of the rotation center P 
of the vibration-insulating compensating optical system Gv be positioned 
opposite to the rear principal point of the vibration-insulating 
compensating optical system Gv with respect to the middle point of the 
overall length of the vibration-insulating compensating optical system Gv. 
The reason for this lies in that the rear principle point of the 
vibration-insulating compensating optical system Gv with which the 
vibration-insulating compensation can be performed most effectively is 
necessary to be displaced by a relatively large degree. On the other hand, 
the displacement of the lens disposed away from the rear principal point 
must be made smaller. As a result, the vibration-insulating compensation 
can be performed only in a small space in the vertical direction with 
respect to the optical axis of the vibration-insulating optical system. 
Therefore, the shape of the mechanism for holding the lens and the 
arrangement of it can be freely determined when the overall structure of 
the optical system is designed. 
In order to maintain a satisfactory aberration by a small size and light 
weight vibration-insulating compensating optical system Gv for performing 
the vibration-insulating compensation by rotational tilting of the optical 
axis, it is preferable that the structure be formed by a double convex 
lens, a negative meniscus lens whose concave faces the object and one or a 
plurality of positive lenses in sequence order from the portion adjacent 
to the object. 
Then, preferred embodiments, in which the vibration-insulating compensating 
optical system according to the present invention is applied to so-called 
an inner focus telephoto lens, will be described with reference to the 
drawings. The structure of each of the embodiments is formed by arranging, 
in sequence order from the portion adjacent to the object, a first lens 
group G.sub.1 having positive refractive power, a second lens group 
G.sub.2 having negative refractive power and a third lens group having 
positive refractive power. The third lens group serves as the 
vibration-insulating compensating optical system Gv according to the 
present invention so as to be made eccentric with respect to the optical 
axis of the overall system. As a result, the deviation of the overall 
system or image blurring can be compensated. In the above-described 
structure, the fixed lens group GF forms a substantial afocal system by 
the first lens group G.sub.1 having positive refractive power and the 
second lens group G.sub.2 having negative refractive power. Its short 
range focusing can be realized by the movement of the second lens group 
G.sub.2 having negative refractive power along the optical axis. 
FIGS. 1, 2, 3, 4 and 5 illustrate the structures of the lens according to 
the embodiments of the present invention. 
According to each of the embodiments, the first lens group G.sub.1 having 
positive refractive power comprises, in sequence order from the portion 
adjacent to the object, two positive lenses L.sub.11 and L.sub.12 whose 
stronger surface confronts the object, double concave negative lens 
L.sub.13 and laminated meniscus lens disposed with a relatively wide air 
layer interposed and consisting of a negative meniscus lens L.sub.14 and a 
positive meniscus lens L.sub.15. The second lens group G.sub.2 having 
negative refractive power comprises, in sequence order from the portion 
adjacent to the object, a negative lens formed by laminating a double 
convex lens L.sub.21 and a double concave lens L.sub.22, and a double 
concave negative lens L.sub.23. A parallel flat plate F disposed in the 
vibration-insulating compensating optical system Gv adjacent to the image 
is a filter acting to permit only light having a predetermined wavelength 
band to pass through and also acting to prevent invasion of dust from the 
rear direction to the lens due to the vibrations of the 
vibration-insulating compensating optical system. 
Then, the embodiments will be respectively described. 
First Embodiment 
The first embodiment according to the present invention and shown in FIG. 1 
comprises, as described above, the vibration-insulating compensating 
optical system Gv formed by three lens factors L.sub.1, L.sub.2 and 
L.sub.3, in order from a position adjacent to the fixed lens group GF 
toward the image. Specifically, the third factor L.sub.3 is formed by a 
single positive meniscus lens whose concave faces the object. Image 
blurring due to variations of the overall body of the optical system is 
compensated by making the three factors integrally eccentric with respect 
to the optical axis with the parallel relationship maintained. That is, 
the vibration-insulating compensating optical system Gv compensates image 
blurring by its eccentric movement performed in such a manner that an 
image, which tends to move vertically with respect to the optical axis due 
to the vibrations of the overall body of the optical system, is shifted in 
the inverse direction. The principle of this action has been disclosed in 
detail in Japanese Patent Publication No. 41-8558. The quantity of 
compensation according to this embodiment is 1 mm and the quantity of 
eccentricitY of the vibration-insulating compensating optical system Gv 
required to perform the compensation is also 1 mm. The details of the 
first embodiment is shown in Table 1. 
According to the first embodiment, vibration insulation can be achieved by 
making the vibration-insulating compensating optical system Gv eccentric 
in such a manner that it is rotated by a small angle so as to change the 
inclination with respect to the optical axis as an alternative to making 
the vibration-insulating compensating optical system Gv eccentric with the 
parallel relationship maintained. That is, as shown in FIG. 1A, image 
blurring due to the variations of the overall body of the optical system 
can be compensated by tilting, by a small angle, the overall body of the 
vibration-insulating compensating optical system Gv relative to point P on 
the optical axis. Image blurring due to the vertical movement of an image 
with respect to the optical axis due to the vibrations of the overall body 
of the optical system is compensated by the eccentric movement in which 
the vibration-insulating compensating optical system Gv is tilted. 
As shown in FIG. 1A, image blurring by 0.5 mm on the image plane can be 
compensated by arranging the position of the rotation center P of the 
vibration-insulating compensating optical system Gv to be the apex of the 
lens surface of the vibration-insulating compensating optical system Gv 
which is nearest to the object and by tilting the optical axis of the 
vibration-insulating compensating optical system Gv by 1.125.degree. with 
respect to the optical axis of the overall body of the optical system. 
It is preferable to obtain a further improved compensation effect that the 
position of the rotation center P of the vibration-insulating compensating 
optical system Gv be determined at a position relatively away from the 
diaphragm S than the central position of the vibration-insulating 
compensating optical system Gv. The position of the rotation center P of 
the vibration-insulating compensating optical system Gv may be determined 
outside the vibration-insulating compensating optical system Gv as an 
alternative to the inner portion of the same. 
Second Embodiment 
As shown in FIG. 2, the second embodiment structured in such a manner that 
the third factor L.sub.3 of the vibration-insulating compensating optical 
system Gv is constituted by two elements that is, in sequence order from 
the portion adjacent to the object, a negative meniscus lens L.sub.31 
whose convex faces the object and a double convex positive lens L.sub.32 
positioned away from each other. The details of the second embodiment are 
shown in Table 2. 
Third Embodiment 
As shown in FIG. 3, the structure according to the third embodiment is 
formed in such a manner that the third factor L.sub.3 is constituted by 
laminating the negative meniscus lens L.sub.31 whose convex faces the 
object and double convex positive lens L.sub.32. As a result of the 
structure in which the two elements forming the third factor L.sub.3 are 
laminated to each other, the supporting can be easily conducted and the 
durability against vibrations can be improved. The details of the third 
embodiment are shown in Table 3. 
Fourth Embodiment 
As shown in FIG. 4, the structure according to the fourth embodiment is 
formed by laminating the first factor L.sub.1 of the vibration-insulating 
compensating optical system Gv and the second factor L.sub.2 of the same 
are laminated to each other. The structure according to this embodiment 
exhibits the most simple structure but exhibits a further durability 
against vibrations. The details of the fourth embodiment are shown in 
Table 4. 
Fifth Embodiment 
As shown in FIG. 5, the structure according to the fifth embodiment of the 
present invention is, similarly to the vibration-insulating optical system 
according to the first embodiment as shown in FIG. 1A, arranged to perform 
the vibration-insulating compensation by rotationally tilting the position 
of the rotation center P of the vibration-insulating compensating optical 
system Gv as the apex P.sub.4 of the surface of the lens of the 
vibration-insulating compensating optical system Gv which is the nearest 
to the object. Also according to the fifth embodiment, image blurring of 
0.5 mm on the image plane can be compensated by tilting the optical axis 
of the vibration-insulating compensating optical system Gv by 
1.125.degree. with respect to the optical axis of the overall body of the 
optical axis. 
The details of the fifth embodiment are shown in Table 5. Table 6 shows the 
position of each of the rotational centers and the maximal rotational 
angles at the rotational centers when it is assumed that an optional 
position of the rotational center on the optical axis of the overall body 
of the optical system with which the maximal image blurring compensation 
quantity .DELTA.y on the image plane becomes 0.5 mm is Pn (where n=1 to 
8). According to the above-described embodiments, although only the fixed 
filter having no power is provided in the portion of the 
vibration-insulating compensating optical system Gv adjacent to the image, 
a lens group substantially having refractive power may be provided in the 
above-described portion. As the lens group GF disposed more adjacently to 
the object than the vibration-insulating compensating optical system Gv, 
either lens group having a positive refractive power or that having a 
negative refractive power may be employed. It is preferable, as described 
above, that it may be a substantial afocal system having weak refractive 
power. Furthermore, not only the above-described first embodiment, but 
also the other embodiments, of course, is able to perform the compensation 
by the rotational tilting of the vibration-insulating compensating optical 
system Gv. 
The details of each of the embodiments are shown in Tables 1 to 5, where 
symbol r represents the curvature radius of each of the lens surfaces, 
symbol d represents the interval between lens surfaces, symbols Abbe and 
symbol n respectively represent the Abbe's number and the refractive index 
with respect to the line d (.lambda.=487.6 nm), numeral positioned at the 
left ends represent the order from the object, symbol f represents the 
focal distance of the overall body of the system, symbol FNO represents 
the F-number and symbol 2.omega. represents the field angle. 
TABLE 1 
______________________________________ 
(First embodiment) 
f = 297.0 FNo = 2.8 2.omega. = 8.3.degree. 
r d Abbe n 
______________________________________ 
1 109.927 15.60 82.6 1.49782 
2 13476.664 .30 
3 114.120 16.50 82.6 1.49782 
4 -473.430 3.70 
5 -370.500 4.50 35.2 1.74950 
6 307.534 35.98 
7 83.463 2.30 53.9 1.71300 
8 37.445 12.90 69.9 1.51860 
9 179.291 3.01 
10 221.841 7.60 33.9 1.80384 
11 -81.907 1.90 60.7 1.60311 
12 89.196 5.40 
13 -140.000 1.90 52.3 1.74810 
14 70.483 14.84 
15 135.437 6.90 82.6 1.49782 
16 -72.013 1.60 
17 -51.654 6.50 28.6 1.79504 
18 -207.775 5.50 
19 -336.248 5.60 31.6 1.75692 
20 -66.780 38.35 
21 .infin. 2.00 64.1 1.51680 
22 .infin. Bf = 78.50 
______________________________________ 
TABLE 2 
______________________________________ 
(Second Embodiment) 
f = 297.0 FNo = 2.8 2.omega. = 8.3.degree. 
r d Abbe n 
______________________________________ 
1 118.435 12.80 82.6 1.49782 
2 943.895 .30 
3 110.718 16.80 82.6 1.49782 
4 -478.068 3.70 
5 -401.348 4.50 28.3 1.72825 
6 404.516 39.09 
7 81.287 2.30 51.1 1.73350 
8 37.600 12.90 64.1 1.51680 
9 184.094 2.94 
10 225.947 7.10 25.4 1.80518 
11 -90.000 1.90 54.6 1.51454 
12 83.993 5.40 
13 -126.890 1.90 45.4 1.79668 
14 71.318 15.17 
15 120.509 6.90 82.6 1.49782 
16 -83.026 1.70 
17 -55.175 3.50 38.8 1.67163 
18 -360.867 5.50 
19 90000.000 3.00 45.0 1.74400 
20 228.368 1.00 
21 262.612 7.00 50.8 1.65844 
22 -70.796 35.21 
23 .infin. 2.00 64.1 1.51680 
24 .infin. Bf = 78.99 
______________________________________ 
TABLE 3 
______________________________________ 
(Third Embodiment) 
f = 297.0 FNo = 2.8 2.omega. = 8.3.degree. 
r d Abbe n 
______________________________________ 
1 110.846 15.60 82.6 1.49782 
2 6000.000 .30 
3 117.512 16.50 82.6 1.49782 
4 -437.495 3.70 
5 -351.000 4.50 35.2 1.74950 
6 348.474 36.13 
7 105.163 2.30 53.9 1.71300 
8 35.896 14.40 67.9 1.59319 
9 200.588 3.01 
10 224.264 7.60 33.9 1.80384 
11 -81.000 1.90 58.5 1.61272 
12 91.256 5.40 
13 -141.300 1.90 52.3 1.74810 
14 70.821 14.85 
15 103.002 6.90 82.6 1.49782 
16 -108.000 5.60 
17 -60.197 3.00 32.2 1.67270 
18 -413.521 5.50 
19 1607.481 3.50 45.0 1.74400 
20 60.000 9.20 42.0 1.66755 
21 -71.253 38.35 
22 .infin. 2.00 64.1 1.51680 
23 .infin. Bf = 70.06 
______________________________________ 
TABLE 4 
______________________________________ 
(Fourth Embodiment) 
f = 297.0 FNo = 2.8 2.omega. = 8.3.degree. 
r d Abbe n 
______________________________________ 
1 114.835 17.60 82.6 1.49782 
2 2387.746 .30 
3 105.979 18.10 82.6 1.49782 
4 -393.398 3.50 
5 -328.200 4.70 35.2 1.74950 
6 386.924 30.50 
7 83.383 2.20 55.6 1.69680 
8 38.417 15.00 70.4 1.48749 
9 203.746 2.52 
10 412.244 8.40 33.9 1.80384 
11 -81.738 2.00 60.7 1.60311 
12 94.919 5.10 
13 -190.000 2.00 52.3 1.74809 
14 65.477 14.10 
15 172.821 9.50 82.6 1.49782 
16 -43.803 6.50 33.9 1.80384 
17 -498.867 5.50 
18 425.192 5.60 31.6 1.75692 
19 -85.107 37.70 
20 .infin. 2.00 64.1 1.51680 
21 .infin. Bf = 80.97 
______________________________________ 
TABLE 5 
______________________________________ 
(Fifth Embodiment) 
f = 297.0 FNo = 2.8 2.omega. = 8.3.degree. 
r d Abbe n 
______________________________________ 
1 112.780 17.60 82.6 1.49782 
2 2634.455 .30 
3 108.261 18.10 82.6 1.49782 
4 -397.703 3.50 
5 -332.243 4.70 35.2 1.74950 
6 383.650 28.87 
7 84.625 2.20 55.6 1.69680 
8 38.764 15.00 70.4 1.48749 
9 210.869 4.00 
10 471.818 8.40 33.9 1.80384 
11 -78.537 2.00 60.7 1.60311 
12 98.621 5.10 
13 -159.458 2.00 52.3 1.74810 
14 69.682 13.90 
15 146.361 6.90 69.9 1.51860 
16 -69.719 1.60 
17 -50.689 6.50 25.4 1.80518 
18 -200.551 5.50 
19 -295.108 5.60 28.2 1.74000 
20 -64.433 39.20 
21 .infin. 2.00 64.1 1.51680 
22 .infin. Bf = 77.67 
______________________________________ 
TABLE 6 
______________________________________ 
Positions of Rotation 
Mamimal Rotary 
Center Pn Angle 
Pn (mm) (degree) 
______________________________________ 
P.sub.1 -200.0 .+-.0.127 
P.sub.2 -50.0 .+-.0.380 
P.sub.3 -10.0 .+-.0.807 
P.sub.4 0.0 .+-.1.125 
P.sub.5 +8.5 .+-.1.642 
P.sub.6 +76.1 .+-.0.566 
P.sub.7 +126.1 .+-.0.285 
P.sub.8 +1026.1 .+-.0.285 
______________________________________ 
As is shown from the above-described tables, according to each of the 
above-described embodiments, the reduction in the aberration change due to 
the eccentricity compensation and the shortening of the overall length of 
the vibration-insulating compensating optical system Gv can be realized 
simultaneously such that: 
26.1 mm according to the first embodiment 
28.6 mm according to the second embodiment 
33.7 mm according to the third embodiment 
27.1 mm according to the fourth embodiment 
26.1 mm according to the fifth embodiment 
All of the above-described embodiments are able to meet the conditions of 
the present invention. Table 7 shows data corresponding to each of the 
conditions. 
TABLE 7 
______________________________________ 
(Data Corresponding to the Conditions) 
Conditions 
for Present 
Embodiments 
Invention 1 2 3 4 5 
______________________________________ 
(1) .phi..sub.12 /.phi. 
-7.6 .times. 
6.0 .times. 
9.5 .times. 
-2.8 .times. 
-6.5 .times. 
10.sup.-2 
10.sup.-2 
10.sup.-3 
10.sup.-1 
10.sup.-2 
##STR1## 0.262 0.117 0.183 0.493 0.277 
##STR2## -0.09 -0.02 -0.03 -0.18 -0.07 
(4) .phi. .multidot. D.sub.2 
4.6 .times. 
4.6 .times. 
4.6 .times. 
4.6 .times. 
5.5 .times. 
10.sup.-2 
10.sup.-2 
10.sup.-2 
10.sup.-2 
10.sup.-2 
(5) q.sub.2 
1.66 1.34 1.36 1.19 1.68 
(6) .phi..sub.12 /R1 
1.91 .times. 
3.15 .times. 
8.86 .times. 
-5.57 .times. 
1.85 .times. 
10.sup.-6 
10.sup.-7 
10.sup.-10 
10.sup.-6 
10.sup.-6 
______________________________________ 
According to the embodiments of the present invention, the lens group GF of 
the vibration-insulating compensating optical system Gv adjacent to the 
object comprises the first lens group G.sub.1 of so-called an inner focus 
telephoto lens and having positive refractive power and the second lens 
group G.sub.2 serving as the focusing group and movable along the optical 
axis. However, the present invention is not limited to the above-described 
group structure. A zoom lens may be structured by the overall body of the 
vibration-insulating photographing optical system in such a manner that a 
magnification system movable on the optical axis is employed. For example, 
as shown in FIG. 6, the vibration-insulating compensating optical system 
Gv according to the present invention may be disposed in the positive lens 
group IV serving as the relay system of so-called a four-group afocal zoom 
lens structured by, in sequence order from the portion adjacent to the 
object, a positive, a negative, a positive and a positive group. 
Furthermore, a magnification system formed by three groups consisting of a 
positive first lens group I, a negative second lens group II and a 
positive third lens group III may be provided in the forward fixed lens 
group GF. According to the vibration-insulating zoom lens shown in FIG. 6, 
the positive first lens group I is arranged to be moved along the optical 
axis so as to perform the focusing and the second lens group II and the 
third lens group III are relatively moved so as to perform the zooming. 
The portion between the third lens group III and the fourth lens group IV 
is arranged to cause the Rand light to run substantially parallel. 
Although the invention has been described in its preferred form with a 
certain degree of particularly, it is understood that the present 
disclosure of the preferred from has been changed in the details of 
construction and the combination and arrangement of parts may be resorted 
to without departing from the spirit and the scope of the invention as 
hereinafter claimed.