JP6742807B2 - Photographing optical system and imaging device - Google Patents

Description

The present invention relates to a photographing optical system capable of controlling the light amount of a photographing light flux.

In general, it is preferable that the photographing optical system can form a blurred image in which the light amount is not concentrated on the contour of the out-of-focus image (blurred image) and the light amount is smoothly distributed from the central portion to the peripheral portion. However, the appearance of the blurred image changes depending on the distance between the in-focus subject and the subject outside the depth of field from the photographing optical system and the aberration of the photographing optical system. Therefore, it is difficult to form a preferable blurred image in the entire photographing area.

Patent Documents 1 and 2 disclose optical systems including an apodization filter. In Patent Documents 1 and 2, the apodization filter is a transmittance distribution filter configured such that the amount of transmitted light decreases in a direction orthogonal to the optical axis as the distance from the optical axis increases. With such an apodization filter, an intensity distribution can be added to the photographing light flux, and a good defocus image (blurred image) can be formed.

JP-A-09-236740 JP-A-11-231195

In general, it is preferable that the transmittance distribution given to the light flux by the apodization filter be centrosymmetric with respect to the optical axis. In Patent Documents 1 and 2, the apodization filter is arranged in the vicinity of the diaphragm in order to give the luminous flux of each angle of view a transmittance distribution with high central symmetry.

However, the optical systems of Patent Documents 1 and 2 reduce the effect obtained when vignetting occurs. Vignetting means that part of a light beam is vignetting, and is also called vignetting. It is difficult to completely eliminate vignetting in order to improve the imaging performance of the photographing optical system and to reduce the size and weight of the photographing lens system. However, in a photographic optical system with vignetting, the regions passing through the diaphragm do not match between the on-axis light beam and the off-axis light beam. Therefore, the obtained effect differs depending on the angle of view. Generally, the off-axis light beam passes through a narrower range than the on-axis light beam. Therefore, if the transmittance distribution is formed to match the on-axis light flux, the effect of the transmittance distribution cannot be obtained with the off-axis light flux.

Therefore, the present invention provides an image pickup optical system and an image pickup apparatus capable of satisfactorily obtaining an out-of-focus image of a light flux at all angles of view even when vignetting occurs.

An imaging optical system according to one aspect of the present invention includes a diaphragm, a first apodization filter arranged on the object side of the diaphragm, and a second apodization filter arranged on the image plane side of the diaphragm. However, regarding both the first apodization filter and the second apodization filter, distances from the optical axis in the radial direction orthogonal to the optical axis are r1 and r2 (r1<r2), and the distance r1 is from the optical axis. When the transmittances at positions separated by r2 are T(r1) and T(r2),
T(r1)≧T(r2)
And a region on the first apodization filter where the maximum angle of view of the meridional light beam is incident when the diaphragm is opened, and the meridional light beam of the maximum angle of view is incident when the diaphragm is opened. and the region on the second apodization filter, at least one of, wherein the go and such include a point on the optical axis.

Imaging apparatus as another aspect of the present invention comprises said imaging optical system and an imaging element you photoelectrically convert an optical image formed through the photographic optical system.

Other objects and features of the invention are described in the examples below.

According to the present invention, it is possible to provide an image pickup optical system and an image pickup apparatus capable of satisfactorily obtaining an out-of-focus image of a light flux at all angles of view even when vignetting occurs.

It is a cross-sectional view of a photographing optical system in the present embodiment. It is explanatory drawing of conditional expression (4) in this embodiment. 3 is a cross-sectional view of a photographing optical system in Example 1. FIG. 6 is a diagram showing a transmittance distribution of a transmittance distribution filter in Example 1. FIG. 6 is a diagram showing a transmittance distribution given to an off-axis light beam by a transmittance distribution filter in Example 1. FIG. 5 is a diagram showing pupil transmittance distributions of an on-axis light beam and an off-axis light beam in Example 1. FIG. 6 is a cross-sectional view of a photographing optical system in Example 2. FIG. FIG. 9 is a diagram showing a transmittance distribution of a transmittance distribution filter in the second embodiment. FIG. 9 is a diagram showing pupil transmittance distributions of an on-axis light beam and an off-axis light beam in the second embodiment. 7 is a cross-sectional view of a photographing optical system in Example 3. FIG. FIG. 9 is a diagram showing a transmittance distribution of a transmittance distribution filter in Example 3. FIG. 9 is a diagram showing pupil transmittance distributions of an on-axis light beam and an off-axis light beam in the third embodiment. 9 is a cross-sectional view of a photographing optical system in Example 4. FIG. FIG. 8 is a diagram showing a transmittance distribution of a transmittance distribution filter in Example 4. FIG. 9 is a diagram showing pupil transmittance distributions of an on-axis light beam and an off-axis light beam in Example 4. 16 is a cross-sectional view of the taking optical system in Example 5. FIG. FIG. 9 is a diagram showing a transmittance distribution of a transmittance distribution filter in Example 5. FIG. 16 is a diagram showing pupil transmittance distributions of an on-axis light beam and an off-axis light beam in Example 5; 16 is a cross-sectional view of the taking optical system in Example 6. FIG. FIG. 10 is a diagram showing a transmittance distribution of a transmittance distribution filter in Example 6. FIG. 16 is a diagram showing pupil transmittance distributions of an on-axis light beam and an off-axis light beam in Example 6. In this embodiment, it is a figure which shows conditional expression (7). In this embodiment, it is a figure which shows the conditional expression (8) regarding the filter A. In this embodiment, it is a figure which shows the conditional expression (8) regarding the filter B. In this embodiment, it is a figure which shows the conditional expression (8) regarding the filter C. In this embodiment, it is a figure which shows the conditional expression (8) regarding the filter E. It is a block diagram of the imaging device in this embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The photographing optical system of the present embodiment is a photographing lens capable of controlling a blurred image (out-of-focus image) when photographing a stereoscopic subject, and has a plurality of lens groups (optical elements) and a diaphragm. Further, the photographing optical system has at least one transmittance distribution filter (apodization filter) before and after the diaphragm. Here, the three-dimensional subject is a subject including a plurality of portions having different distances, and particularly means a subject having a point separated from the focal plane of the photographing lens by a depth of field or more at the time of photographing. At this time, an out-of-focus image (blurred image) is formed on the image plane (image plane).

Since the blurred image becomes larger as the distance from the focal plane is larger than the depth of field, it is necessary to form the blurred image well. Specifically, when the diameter of the blurred image becomes larger than about 1 to 2% with respect to the radius of the image circle of the photographing optical system, the blurred image can be recognized. Here, the image circle is a circle on which a light ray passing through the effective diameter of the taking lens forms an image. The imaging surface corresponds to the imaging surface of a solid-state imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that receives an image when a taking lens such as a video camera or a digital camera is used. Further, the image forming surface corresponds to the film surface when a taking lens for a silver distant camera is used. The radius of the image circle may be the maximum image height of the image pickup surface or the film surface in the image pickup apparatus.

In the present embodiment, “controlling” a blurred image means giving a transmittance distribution to the light flux of each angle of view using the above-mentioned transmittance distribution filter, and comparing with the case without the transmittance distribution filter, the blurred image Is to change the light intensity distribution of. A blurred image with a large amount of light in the outer peripheral portion (peripheral portion) has a strong contour, which is not preferable. Therefore, it is preferable to make the transmittance of the peripheral portion of the blurred image lower than that of the central portion.

2. Description of the Related Art Conventionally, as a method for improving a blurred image, a photographing optical system configured by disposing a transmittance distribution filter in the vicinity of a diaphragm is known. By disposing the transmittance distribution filter in the vicinity of the stop, it is possible to match the regions of the light flux of each angle of view that pass through the transmittance distribution filter, and to effectively obtain the apodization effect. However, generally, in the photographing optical system, vignetting occurs with respect to the off-axis light beam, and the off-axis light beam does not pass through the peripheral portion of the diaphragm. At this time, if a transmittance distribution filter is arranged in the vicinity of the diaphragm, the apodization effect cannot be effectively obtained. Therefore, the photographing optical system of the present embodiment has a plurality of lens groups and a diaphragm, and has at least one transmittance distribution filter before and after the diaphragm. With such a configuration, an apodization effect can be effectively obtained even with respect to off-axis light flux.

Hereinafter, with reference to FIG. 1, the passing ranges of the on-axis light flux and the off-axis light flux in the image-taking optical system (shooting lens) will be described. FIG. 1 is a sectional view of a photographing optical system 100 according to this embodiment. The photographic optical system 100 includes a diaphragm SP, a lens 41 (front group, first optical element) arranged on the object side of the diaphragm SP, and a lens 42 (rear group) arranged on the image plane IP side of the diaphragm SP. , A second optical element). A transmittance distribution filter (apodization filter) is arranged on the cross sections 31 and 32 of the photographing optical system 100.

The heights from the optical axis OA through which the on-axis light flux 10 and the off-axis light flux 20 (the most off-axis light flux) pass are different from each other at a position away from the stop SP. The off-axis light beam 20 is a light beam that forms an image outside the optical axis, and in FIG. 1, a light beam that is incident on and passes through the photographing optical system 100 from below the axis (on the optical axis OA) is representatively shown. ing. Conventionally, the transmittance distribution filter is arranged in the vicinity of the stop because the transmittance distribution filter is arranged at a position where the light fluxes at respective angles of view overlap. When the transmittance distribution filter is arranged at a position away from the stop, the off-axis light flux passes through a position away from the optical axis, so that the off-axis light flux is affected by the asymmetric transmittance distribution. The following description will be made on the assumption that the transmittance distribution of the transmittance distribution filter is centrally symmetric (symmetrical with respect to the optical axis OA) and the transmittance is smaller in the peripheral portion than in the central portion.

When the off-axis light beam 20 passes through the transmittance distribution filter, the transmittance becomes lower as the light beam is farther from the optical axis OA. When the transmittance distribution filter is arranged on the cross section 31 in front of the diaphragm SP (on the object side of the diaphragm SP), the light rays 12 and the light rays 13 have the same transmittance with respect to the axial light flux 10. On the other hand, regarding the off-axis light beam 20, the light ray 22 has the highest transmittance, and the lighter the ray 23, the lower the transmittance. On the contrary, when the transmittance distribution filter is arranged on the cross section 32 (on the image plane IP side of the diaphragm SP) behind the diaphragm SP, when the transmittance distribution filter is arranged on the cross section 31 for the axial light flux 10. Similarly, the light ray 12 and the light ray 13 have the same transmittance as each other. On the other hand, regarding the off-axis light flux 20, the transmittance of the light ray 23 is the highest, and the transmittance is lower as it is closer to the light ray 22. This is the reason why the transmittance of the off-axis light flux 20 is asymmetric with respect to the optical axis OA.

Therefore, in the present embodiment, it is utilized that the high and low transmittances of the light ray 22 and the light ray 23 of the off-axis light flux 20 are opposite to each other before and after the stop SP. For example, like the cross section 31 and the cross section 32, by disposing at least one transmittance distribution filter before and after the stop SP, the transmittance distribution (pupil transmittance distribution) of the off-axis light flux 20 is equivalently center-symmetrical. Can be approached to. Further, at positions apart from the stop SP, the passing positions of the on-axis light beam 10 and the off-axis light beam 20 are different from each other. Therefore, the pupil transmittance distributions of the on-axis light beam 10 and the off-axis light beam 20 can be independently determined by changing the arrangement of the transmittance distribution filter and the transmittance distribution.

The photographing optical system 100 of the present embodiment can control a blurred image when photographing a stereoscopic subject, and has a plurality of optical elements including a lens 41 (front group) and a lens 42 (rear group), and a diaphragm SP. .. Further, the photographing optical system 100 has at least one transmittance distribution filter (apodization filter) before and after the diaphragm SP (on the object side and the image plane side). That is, the photographing optical system 100 has a first apodization filter arranged on the object side of the diaphragm SP and a second apodization filter arranged on the image plane IP side of the diaphragm SP. The first apodization filter and the second apodization filter each have a predetermined transmission so as to change the light amount distribution of the blurred image (out-of-focus image) of the subject (stereoscopic subject) (that is, to control the blurred image). Has a rate distribution.

In the present embodiment, each transmittance distribution filter (both the first apodization filter and the second apodization filter) satisfies the following conditional expression (1).

T(r1)≧T(r2) (where r1<r2) (1)
In conditional expression (1), the transmittances at positions separated by distances r1 and r2 (r1<r2) from the center (optical axis OA) of each transmittance distribution filter in the radial direction (direction orthogonal to the optical axis OA) are respectively calculated. Let T(r1) and T(r2). That is, each transmittance distribution filter has a transmittance distribution in which the transmittance decreases as the distance from the optical axis OA increases. However, each transmittance distribution filter may have a transmittance distribution that does not satisfy the conditional expression (1) in a part of its area, and if the conditional expression (1) is satisfied as a whole, It suffices if it has an evaluated transmittance distribution.

In the present embodiment, the blurred image (out-of-focus image) is not an image that is blurred due to camera shake or subject shake, but is an image formed by an object point separated from the focal plane of the photographing optical system 100 by a depth of field or more on the image plane IP ( Defocused image). As described above, control of a blurred image generated when a stereoscopic object is photographed can be realized by arranging at least one transmittance distribution filter (apodization filter) before and after the aperture stop SP to form a highly symmetrical transmittance distribution. Is.

In the present embodiment, the transmittance distribution filter (apodization filter) forms a predetermined transmittance distribution on a transparent glass plate or lens surface, so that an absorbing substance or a reflecting substance is vapor-deposited or a photosensitive material is applied to form a predetermined transmittance distribution. It is obtained by exposing so that the density becomes. Further, a concave lens made of a light absorbing material (ND glass) can be used, or a flat plate having a light absorption distribution may be used. Further, the transmittance distribution may be made variable by utilizing an electrochromic material or the like.

Conditional expression (1) relates to the transmittance distribution of the transmittance distribution filter. In order to improve the edge-blurring in which the amount of light is large in the peripheral portion (area away from the optical axis OA), the pupil transmittance in the peripheral portion of the light flux is set lower than that in the central portion of the light flux (area near the optical axis OA). There is a need to. If the conditional expression (1) is not satisfied, the amount of light at the peripheral portion of the light flux is made stronger than that at the central portion of the light flux, resulting in a dirty blur with more edges. The transmittance may be constant within a predetermined range. By not lowering the transmittance within a predetermined range from the central portion (optical axis OA), it is possible to increase the amount of light taken in by the photographing optical system 100. In addition, for example, when a transmittance distribution filter using an electrochromic material is used and it is difficult to create a transmittance distribution that changes smoothly, the transmittance may be changed stepwise.

In the present embodiment, the conditional expression (1) may be satisfied in one cross section passing through the optical axis OA. However, if necessary, the conditional expression (1) may be satisfied in a region (entire region) symmetrical with respect to the optical axis OA, that is, the transmittance distribution may be center-symmetrical. It should be noted that, due to manufacturing variations and the like, the point having the highest transmittance may be displaced from the optical axis OA, or the transmittance distribution may be uneven. In such a case, the transmittance error is preferably within 5 to 10%.

In the present embodiment, the transmittance of at least one transmittance distribution filter (at least one of the first apodization filter and the second apodization filter) preferably satisfies the following conditional expression (2).

T1/T0≦0.5 (2)
In the conditional expression (2), T0 is the maximum transmittance within the effective diameter of the transmittance distribution filter (the first apodization filter or the second apodization filter), and T1 is the minimum transmittance within the effective diameter.

Conditional expression (2) relates to the transmittance distribution of the transmittance distribution filter. When the value exceeds the upper limit of the conditional expression (2), it becomes difficult to improve the blurring with an edge and reduce the light amount in the peripheral portion.

In the present embodiment, the distance on the optical axis between the two transmittance distribution filters is e, and the distance from the apex of the most object-side lens surface of the photographing optical system 100 to the image plane (paraxial image plane). When L is L, it is preferable to satisfy the following conditional expression (3).

e/L>0.1 (3)
Conditional expression (3) relates to the distance between the two transmittance distribution filters arranged in the photographing optical system 100. When the value goes below the lower limit of the conditional expression (3), the distances between the two transmittance distribution filters become close to each other, so that it is difficult to independently determine the pupil transmittance distributions of the on-axis light flux 10 and the off-axis light flux 20. become. Therefore, it is difficult to properly set the pupil transmittance distributions of the on-axis light beam 10 and the off-axis light beam 20. More preferably, the conditional expression (3) is set so as to satisfy the following conditional expression (3a).

e/L>0.2 (3a)
In the conditional expressions (3) and (3a), when three or more transmittance distribution filters are arranged in the photographing optical system, the distance e is the position on the optical axis of the plurality of transmittance distribution filters. It is the distance between the two most distant transmittance distribution filters.

In a state where the aperture stop SP is opened (fully opened), a perpendicular line (a perpendicular line of the optical axis OA) passing through an intersection of the upper line of the most off-axis light beam and the upper line of the on-axis light beam intersects with the optical axis OA (foot of the perpendicular line) Is Hb. Similarly, a point (leg of a perpendicular line) where a perpendicular line (a perpendicular line of the optical axis OA) passing through an intersection point between the underline of the most off-axis light beam and the underline of the on-axis light beam intersects with the optical axis OA is defined as Hf. Further, the distance on the optical axis between one of the first apodization filter and the second apodization filter and the stop SP is dj (j=1, 2). Further, the distance on the optical axis between the stop SP and a point near one of the first apodization filter and the second apodization filter on the optical axis of the points Hf and Hb is Dj (j=1, 2). And At this time, it is preferable that the j-th transmittance distribution filter (first apodization filter and second apodization filter) satisfy the following conditional expression (4).

-0.2<(dj-Dj)/L<0.3 (where j=1, 2) (4)
FIG. 2 is an explanatory diagram of conditional expression (4). The transmittance distribution filters F1 and F2 are arranged in the taking optical system 100 of the present embodiment. The transmittance distribution filter F1 is a first (j=1) transmittance distribution filter (first apodization filter) arranged on the object side (front side) of the aperture stop SP. The transmittance distribution filter F2 is a second (j=2) transmittance distribution filter (second apodization filter) arranged on the image plane IP side (rear side) of the diaphragm SP.

The upper line of the on-axis light beam and the upper line of the most off-axis light beam correspond to the light beam 12 and the light beam 22 in FIG. 2, respectively, and indicate the uppermost light beam of the light beam on the ray diagram. Similarly, the underline of the on-axis light flux and the underline of the most off-axis light flux correspond to the light ray 13 and the light ray 23 in FIG. 2, respectively, and indicate the lowest ray of the light flux in the ray diagram. The most off-axis light flux is a light flux having an angle of view for forming an image at a point farthest from the optical axis OA on the image plane IP (imaging surface). The point Hb is a foot of a perpendicular line drawn from the intersection of the light ray 12 and the light ray 22 to the optical axis OA. The point Hf is a foot of a perpendicular line drawn from the intersection of the light ray 13 and the light ray 23 to the optical axis OA. In this embodiment, the first transmittance distribution filter F1 is the first lens surface (the lens surface closest to the object side), and the second transmittance distribution filter F2 is the lens final surface (the lens surface closest to the image plane IP side). ) Are formed respectively.

Conditional expression (4) relates to the arrangement of the transmittance distribution filters F1 and F2. When the value goes below the lower limit of conditional expression (4), the transmittance distribution filters F1 and F2 are too close to the aperture stop SP, which makes it difficult to independently determine the pupil transmittance distributions of the on-axis light flux 10 and the off-axis light flux 20. Become. On the other hand, when the value exceeds the upper limit value of the conditional expression (4), the light flux of each angle of view is separated too much at the positions of the transmittance distribution filters F1 and F2, which makes it difficult to give an appropriate pupil transmittance distribution to every light flux. Become. More preferably, the conditional expression (4) is designed to satisfy the following conditional expression (4a).

-0.1<(dj-Dj)/L<0.2 (4a)
When focusing at infinity, assuming that the focal length of the photographing optical system 100 is f (mm) and the open F value is Fno, it is preferable to satisfy the following conditional expression (5).

10 mm≦f/Fno≦75 mm (5)
Conditional expression (5) relates to the entrance pupil diameter of the photographing optical system 100. If the lower limit of conditional expression (5) is not reached, the area occupied by each blurred image on the image plane IP (imaging plane) becomes too small. At this time, since the transmittance distribution given to the blurred image becomes too small on the imaging surface, the effect of improving the blurred image by the transmittance distribution filter is reduced. Also, since the blur is small, dirty blur is less likely to cause a problem during shooting. On the other hand, when the value exceeds the upper limit of conditional expression (5), the blurred image becomes large, and the area occupied by each blurred image on the imaging surface becomes too large. At this time, since the transmittance distribution given to the blurred image becomes too large, the effect of improving the blurred image by the transmittance distribution filter is reduced. Note that the blurred image with an edge is formed corresponding to the aberration of the photographing optical system. However, in a large blurred image that exceeds the upper limit of conditional expression (5), the influence of aberration on the light amount distribution of the blurred image is small, and dirty blurring is unlikely to be a problem during shooting. More preferably, the conditional expression (5) is designed to satisfy the following conditional expression (5a).

12 mm≦f/Fno≦70 mm (5a)
Further, in the present embodiment, it is preferable that the focal length f (mm) of the photographing optical system 100 satisfies the following conditional expression (6).

10 mm≦f≦140 mm (6)
Conditional expression (6) relates to the focal length f of the photographing optical system. When the value goes below the lower limit of conditional expression (6), the area occupied by each blurred image on the imaging surface becomes too small. At this time, since the transmittance distribution given to the blurred image becomes too small on the imaging surface, the effect of improving the blurred image by the transmittance distribution filter is reduced. Also, since the blur is small, dirty blur is less likely to cause a problem during shooting. On the other hand, when the value exceeds the upper limit of conditional expression (6), the blurred image becomes large, and the area occupied by each blurred image on the imaging surface becomes too large. At this time, since the transmittance distribution given to the blurred image becomes too large, the effect of improving the blurred image by the transmittance distribution filter is reduced. The blurred image with an edge is formed in correspondence with the aberration of the photographing optical system 100. At this time, in a taking optical system that exceeds the upper limit of conditional expression (6), aberrations that deteriorate the light amount distribution of a blurred image are easily suppressed during design. Therefore, dirty blur is unlikely to occur, and the effect of the transmittance distribution filter is reduced. When the upper limit value of the conditional expression (6) is satisfied, a small dot-shaped or thin linear light source or subject is likely to occur in the background due to the background compression effect by the perspective of the photographing optical system 100. For such a subject, the contour of the blurred image is easily noticeable, and the transmittance distribution filter is more effective.

Further, in the present embodiment, regarding at least one transmittance distribution filter (at least one of the first and second apodization filters), when compared at the same position, the transmittance difference in the wavelength range of 430 nm or more and 700 nm or less is: It is preferably within 20%. This condition relates to wavelength dispersion of transmittance. If this condition is not satisfied, the peripheral portion of the blurred image is colored, and the effect of improving the blurred image is reduced.

Further, in the present embodiment, when the effective diameter of at least one transmittance distribution filter (at least one of the first and second apodization filters) is rmax and the distance from the optical axis OA in the radial direction is r, the following conditions are satisfied. It is preferable to satisfy the formula (7).

min(0.9, max(0,-1.6r+1))≤T(r/rmax)≤min(1,-5r+5.5) (7)
In conditional expression (7), min (A, B) means that the smaller value of A and B is taken, and max (A, B) means that the larger value of A and B is taken. ..

Conditional expression (7) relates to the transmittance distribution of the transmittance distribution filter. When the value goes below the lower limit of conditional expression (7), the light amount taken in by the photographing optical system 100 becomes small because the transmittance is low. At this time, the exposure time at the time of shooting becomes long, and camera shake and subject shake easily occur. More preferably, all the transmittance distribution filters are designed so as to satisfy the conditional expression (7).

With respect to at least one transmittance distribution filter (at least one of the first and second apodization filters), when the diameter of the transmittance T0/√e is r0*rmax, within the range of r<0.8*rmax It is preferable that the following conditional expression (8) is satisfied.

0.8*exp(-(1/2)*(r/(0.8*r0)) ² )≤T(r/rmax)≤1.2*exp(-(1/2)*(r/ (1.2*r0)) ² ) (8)
Conditional expression (8) relates to the transmittance distribution of the transmittance distribution filter. When the conditional expression (8) is satisfied, the transmittance distribution becomes close to the Gaussian distribution. In general, the transmittance distribution filter preferably has a Gaussian distribution type transmittance distribution. When the transmittance distribution filter is arranged on the object side of the stop SP, the transmittance distribution on the underline side can be approximated to a Gaussian distribution. On the other hand, when the transmittance distribution filter is arranged on the image side (image surface IP side) of the stop SP, the transmittance distribution on the upper line side can be approximated to a Gaussian distribution.

More preferably, at least one transmittance distribution filter that satisfies the conditional expression (8) is arranged before and after the stop SP. At this time, with respect to the transmittance distribution filters arranged before and after the diaphragm SP, the pupil transmittance distribution of each angle-of-view light beam by combining the transmittance distribution filters can be approximated to a Gaussian distribution. Further, when the transmittance distributions of the transmittance distribution filters arranged before and after the stop SP are not Gaussian distributions, even if the transmittance distributions of the transmittance distribution filters are centrosymmetric, the off-axis light flux 20 obtained by the combination is obtained. The pupil intensity distribution of is not symmetrical about the center (optical axis OA). By designing the transmittance distribution filters before and after the aperture stop SP so as to satisfy the conditional expression (8), it is possible to give a pupil transmittance distribution that is nearly symmetrical with respect to the center with respect to a light flux of any angle of view.

In the present embodiment, with the diaphragm open, in one of the two transmittance distribution filters (apodization filters), the transmittance of the upper line of the maximum angle of view of the luminous flux is higher than the transmittance of the underline thereof, and the maximum angle of view of the other one is used. The transmittance of the lower line of the light flux is preferably higher than the transmittance of the upper line. Here, the maximum angle-of-view light flux is a light flux that forms an image on the outermost side of the image circle. In the image pickup apparatus, the light flux may be a light flux that forms an image at the maximum image height of the image plane IP (image pickup plane or film plane). This condition relates to the relationship between the transmittance distribution filter and the light flux that passes through the transmittance distribution filter. If this condition is not satisfied, the asymmetry of the transmittance distribution given to the maximum angle-of-view light flux by the two transmittance distribution filters becomes stronger, and the transmittance of only one of the upper line and the lower line becomes smaller. On the other hand, if this condition is satisfied, the asymmetry of the transmittance distribution given to the maximum angle of view light flux by the two transmittance distribution filters is weakened, and a pupil transmittance distribution with higher central symmetry can be obtained.

In the present embodiment, with the diaphragm open, in one of the two transmittance distribution filters (apodization filter), the transmittance of the upper line of the meridional light flux at the maximum angle of view is the maximum transmittance, and the transmittance of the lower line of the meridional light flux is The minimum transmittance is preferable. On the other hand, it is preferable that the transmittance of the underline of the meridional luminous flux having the maximum angle of view is the maximum transmittance, and the upper line of the meridional luminous flux is the minimum transmittance. This condition relates to the relationship between the transmittance distribution filter and the light flux that passes through the transmittance distribution filter. This condition is equivalent to the meridional light flux not passing through a point on the optical axis of the transmittance distribution filter. If this condition is not satisfied, the asymmetry of the transmittance distribution given to the maximum angle of view light flux by the two transmittance distribution filters becomes stronger, and the transmittance of only one of the upper line and the lower line becomes smaller. On the other hand, if this condition is satisfied, the asymmetry of the transmittance distribution given to the maximum angle of view light flux by the two transmittance distribution filters is weakened, and a pupil transmittance distribution with higher central symmetry can be obtained. By satisfying this condition, the transmittance distribution filter can be arranged at a position where the on-axis light flux and the off-axis light flux are further separated, and the pupil transmittance distributions of the on-axis light flux and the off-axis light flux are independently controlled. It will be easy.

In the present embodiment, the meridional light flux with the maximum angle of view passes through the optical path that does not include at least one of the points on the optical axis of the two transmittance distribution filters (first and second apodization filters) with the diaphragm open. It is preferable. When the meridional light flux with the maximum angle of view passes through the optical path that does not include both points on the optical axis of the two transmittance distribution filters, the asymmetry of the transmittance distribution that the two transmittance distribution filters give to the maximum angle of view light beam is weakened. .. Therefore, a pupil transmittance distribution with high central symmetry can be obtained. Further, the transmittance distribution filter can be arranged at a position where the on-axis light flux and the off-axis light flux are separated, and it becomes easy to control the pupil transmittance distributions of the on-axis light flux and the off-axis light flux independently.

When the degree of vignetting with respect to the off-axis light flux is largely different before and after the stop SP, the asymmetry of the blurred image becomes strong. In this case, the meridional light flux with the maximum angle of view may pass through the optical path that does not include one of the points on the optical axis of the two transmittance distribution filters. As a result, it is possible to improve the asymmetry by controlling the blurred image of the off-axis light flux while suppressing the influence of the axial light flux on the blurred image.

When the image height of the photographic optical system 100 is y and the maximum image height is Ymax with the stop SP open, the peripheral light amount ratio R at the image height y satisfying y=0.9Ymax is expressed by the following conditional expression (9). ) Is preferably satisfied. Here, the peripheral light amount ratio R is a light amount ratio of an off-axis light beam to an on-axis light beam, and is a peripheral light amount ratio when only vignetting is considered without considering the transmittances of the first and second apodization filters. is there.

R≦0.5 (9)
Conditional expression (9) relates to peripheral dimming of the photographing optical system 100. When the conditional expression (9) is satisfied, vignetting is large, so that the on-axis light flux and the off-axis light flux are further separated. At this time, the transmittance distribution filter can be arranged at a position where the on-axis light flux and the off-axis light flux are separated, and it becomes easy to control the pupil transmittance distributions of the on-axis light flux and the off-axis light flux independently.

Next, with reference to FIG. 3 to FIG. 6, a photographing optical system in Embodiment 1 of the present invention will be described. FIG. 3 is a sectional view of the taking optical system 100a in this embodiment. The imaging optical system 100a includes a lens 41 (front group, first optical element), a lens 42 (rear group, second optical element), and a diaphragm SP. In the photographing optical system 100a, the transmittance distribution filter F1 (first apodization filter) is arranged on the fifth surface (the lens surface closer to the diaphragm SP than the diaphragm SP). Further, in the photographing optical system 100a, the transmittance distribution filter F2 (second apodization filter) is arranged on the seventh surface (lens surface on the image plane IP side of the diaphragm SP and closest to the diaphragm SP). With the transmittance distribution filters F1 and F2, a pupil intensity distribution can be given to the light flux of all angles of view from the on-axis light flux 10 to the off-axis light flux 20 (the most off-axis light flux) to improve the blurred image.

FIG. 4 is a diagram showing the transmittance distributions of the transmittance distribution filters F1 and F2. The outer peripheral portion in FIG. 4 represents the effective diameter of each transmittance distribution filter. The effective diameter of the transmittance distribution filter is the maximum diameter from the optical axis OA of the region through which the light flux passes. 5A and 5B are diagrams showing pupil transmittance distributions given to the off-axis light flux 20 by the transmittance distribution filters F1 and F2, respectively. As can be seen from FIGS. 5A and 5B, the pupil intensity distribution given to the off-axis light flux 20 by each of the transmittance distribution filters F1 and F2 has low symmetry. FIGS. 6A and 6B are diagrams showing pupil transmittance distributions given to the on-axis light flux 10 and the off-axis light flux 20, respectively, in a state where the transmittance distribution filters F1 and F2 are combined. As can be seen from FIGS. 6(A) and 6(B), pupil transmission with high symmetry not only for the on-axis light flux 10 (FIG. 6(A)) but also for the off-axis light flux 20 (FIG. 6(B)). The rate distribution is given.

Next, with reference to FIG. 7 to FIG. 9, an image pickup optical system in Embodiment 2 of the present invention will be described. FIG. 7 is a sectional view of the taking optical system 100b in this embodiment. FIG. 8 is a diagram showing the transmittance distributions of the transmittance distribution filters F1 and F2. 9A and 9B are diagrams showing pupil transmittance distributions given to the on-axis light flux 10 and the off-axis light flux 20, respectively, in a state where the transmittance distribution filters F1 and F2 are combined.

The taking optical system 100b of the present embodiment is different from the taking optical system 100a of the first embodiment described with reference to FIG. 3 in that the transmittance distribution filters F1 and F2 have different transmittance distributions. Other configurations of the photographing optical system 100b are the same as those of the photographing optical system 100a. The transmittance distribution filters F1 and F2 are arranged on the fifth surface and the seventh surface, respectively, similarly to the photographing optical system 100a. As can be seen from FIGS. 9A and 9B, not only the on-axis light beam 10 but also the most off-axis light beam is arranged, although the transmittance distribution filters F1 and F2 are arranged at positions distant from the stop SP. A pupil transmittance distribution with high symmetry is also given to 20.

Next, with reference to FIG. 10 to FIG. 12, a photographing optical system in Embodiment 3 of the present invention will be described. FIG. 10 is a sectional view of the photographing optical system 100c in this embodiment. FIG. 11 is a diagram showing the transmittance distributions of the transmittance distribution filters F1 and F2. 12A and 12B are diagrams showing pupil transmittance distributions given to the on-axis light flux 10 and the off-axis light flux 20, respectively, in a state where the transmittance distribution filters F1 and F2 are combined.

In the photographing optical system 100c of the present embodiment, the transmittance distribution filter F1 is arranged on the tenth surface and the transmittance distribution filter F2 is arranged on the twenty-second surface. With the transmittance distribution filters F1 and F2, it is possible to give a pupil intensity distribution to the luminous flux of all angles of view from the axial luminous flux 10 to the most off-axis luminous flux 20 to improve the blurred image. As can be seen from FIGS. 12(A) and 12(B), not only the on-axis light beam 10 but also the most off-axis light beam is arranged, although the transmittance distribution filters F1 and F2 are arranged at positions distant from the stop SP. A pupil transmittance distribution with high symmetry is also given to 20.

Next, with reference to FIG. 13 to FIG. 15, an image pickup optical system in Embodiment 4 of the present invention will be described. FIG. 13 is a cross-sectional view of the taking optical system 100d in this embodiment. The imaging optical system 100d has three transmittance distribution filters F1, F2, and F3. In the photographing optical system 100d, a transmittance distribution filter F1 (first apodization filter) is arranged on the first surface (lens surface closest to the object). Further, a transmittance distribution filter F2 (second apodization filter) is arranged on the 17th surface. Further, a transmittance distribution filter F3 (third apodization filter) is arranged on the thirteenth surface (between the lens surface closest to the diaphragm SP and closer to the image surface IP than the diaphragm SP). There is.

In the present embodiment, the transmittance distribution filter F3 forms the transmittance distribution on the 13th surface, but it may be an ND filter having a distribution in the amount of light absorption as described above. With the transmittance distribution filters F1, F2, and F3, the pupil intensity distribution can be given to the luminous flux of all angles of view from the on-axis luminous flux 10 to the off-axis luminous flux 20 (the most off-axis luminous flux) to improve the blurred image.

FIG. 14A is a diagram showing the transmittance distributions of the transmittance distribution filters F1 and F2. FIG. 14B is a diagram showing the transmittance distribution of the transmittance distribution filter F3. FIGS. 15A and 15B are diagrams showing pupil transmittance distributions given to the on-axis light flux 10 and the off-axis light flux 20, respectively, in a state where the transmittance distribution filters F1, F2, and F3 are combined. As can be seen from FIGS. 15(A) and 15(B), not only the on-axis light beam 10 but also the off-axis light beam 20 is provided, although the transmittance distribution filters F1 and F2 are arranged at positions distant from the stop SP. A pupil transmittance distribution having high symmetry is also given to (the most off-axis light flux). In addition, in the present embodiment, the contours of the blurred image can be improved by using the transmittance distribution filters F1 and F2, and the light amount distribution of the entire blurred image can be made an appropriate distribution by using the transmittance distribution filter F3.

Next, with reference to FIG. 16 to FIG. 18, a photographing optical system in Embodiment 5 of the present invention will be described. FIG. 16 is a sectional view of the taking optical system 100e in this embodiment. FIG. 17 is a diagram showing the transmittance distributions of the transmittance distribution filters F1 and F2. 18A and 18B are diagrams showing pupil transmittance distributions given to the on-axis light flux 10 and the off-axis light flux 20, respectively, in a state where the transmittance distribution filters F1 and F2 are combined.

In the photographing optical system 100e of the present embodiment, the transmittance distribution filter F1 is arranged on the seventh surface, and the transmittance distribution filter F2 is arranged on the twenty-first surface (lens final surface, that is, the lens surface closest to the image plane IP). It is arranged. With the transmittance distribution filters F1 and F2, it is possible to give a pupil intensity distribution to the luminous flux of all angles of view from the axial luminous flux 10 to the most off-axis luminous flux 20 to improve the blurred image. As can be seen from FIGS. 18(A) and 18(B), not only the on-axis light beam 10 but also the off-axis light beam 20 is provided, even though the transmittance distribution filters F1 and F2 are arranged at positions distant from the stop SP. A pupil transmittance distribution with high symmetry is also given to.

Next, with reference to FIG. 19 to FIG. 21, a photographing optical system in Embodiment 6 of the present invention will be described. FIG. 19 is a sectional view of the taking optical system 100f in this embodiment. FIG. 20 is a diagram showing the transmittance distributions of the transmittance distribution filters F1 and F2. 21A and 21B are diagrams showing pupil transmittance distributions given to the on-axis light flux 10 and the off-axis light flux 20, respectively, in a state where the transmittance distribution filters F1 and F2 are combined.

In the photographing optical system 100f of the present embodiment, the transmittance distribution filter F1 is arranged on the first surface (lens surface closest to the object side), and the 21st surface (lens final surface, that is, the lens surface closest to the image plane IP side). ) Is provided with the transmittance distribution filter F2. With the transmittance distribution filters F1 and F2, the pupil intensity distribution can be given to the light flux of all angles of view from the on-axis light flux 10 to the off-axis light flux 20 (the most off-axis light flux) to improve the blurred image. As can be seen from FIGS. 21(A) and 21(B), not only the on-axis light beam 10 but also the off-axis light beam 20 despite the transmittance distribution filters F1 and F2 being arranged at the positions distant from the stop SP. A pupil transmittance distribution with high symmetry is also given to.

Numerical Examples 1 to 6 corresponding to the above-described Examples 1 to 6 will be shown below. In each numerical example, r is the radius of curvature of the i-th surface from the object side (mm), d is the surface spacing (mm) on the i-th and i+1-th axes from the object side, and nd and vd are respectively. The refractive index and the Abbe number of the i-th optical member. The focal length f, the F number Fno, and the angle of view 2ω (degrees) are values when an object at infinity is focused. BF is the back focus. The total lens length represents the distance from the first surface to the image plane.

Further, the aspherical surface is represented by adding a symbol "*" after the surface number. As for the aspherical shape, X is the amount of displacement from the surface vertex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, A4, A6, When A8, A10, and A12 are aspherical surface coefficients, they are represented by the following expression (10).

Further, for example, the display of “e±Z” means “10 ^±Z ”.

(Numerical Example 1)
Unit mm
Surface data Surface number rd nd vd Effective diameter
1 35.778 2.93 1.80100 35.0 29.78
2 80.155 0.49 28.89
3 22.367 5.02 1.69680 55.5 24.75
4 ∞ 1.01 1.62588 35.7 22.98
5 15.375 8.35 19.20
6 (aperture) ∞ 8.91 17.99
7 -16.157 3.86 1.71736 29.5 16.42
8 -252.032 0.53 23.30
9 -85.452 3.95 1.77250 49.6 23.31
10 -22.034 0.10 24.59
11 190.588 4.69 1.77250 49.6 30.11
12 -40.055 36.00 30.67
Image plane ∞

Various data

Focal length 50.00
F number 2.00
Angle of view 23.40
Image height 21.64
Lens total length 75.84
BF 36.00


Entrance pupil position 21.21
Exit pupil position -37.27
Front principal point position 37.09
Rear principal point position -14.00

Single lens Data lens Start surface Focal length
1 1 78.37
2 3 32.10
3 4 -24.57
4 7 -24.23
5 9 37.42
6 11 43.23

(Numerical example 2)
Unit mm

Surface data Surface number rd nd vd Effective diameter
1 35.778 2.93 1.80100 35.0 29.78
2 80.155 0.49 28.89
3 22.367 5.02 1.69680 55.5 24.75
4 ∞ 1.01 1.62588 35.7 22.98
5 15.375 8.35 19.20
6 (aperture) ∞ 8.91 17.99
7 -16.157 3.86 1.71736 29.5 16.42
8 -252.032 0.53 23.30
9 -85.452 3.95 1.77250 49.6 23.31
10 -22.034 0.10 24.59
11 190.588 4.69 1.77250 49.6 30.11
12 -40.055 36.00 30.67
Image plane ∞

Various data

Focal length 50.00
F number 2.00
Angle of view 23.40
Image height 21.64
Lens total length 75.84
BF 36.00

Entrance pupil position 21.21
Exit pupil position -37.27
Front principal point position 37.09
Rear principal point position -14.00

Single lens Data lens Start surface Focal length
1 1 78.37
2 3 32.10
3 4 -24.57
4 7 -24.23
5 9 37.42
6 11 43.23

(Numerical example 3)
Unit mm

Surface data Surface number rd nd vd Effective diameter
1 61.880 2.99 1.83481 42.7 54.05
2 27.026 8.34 43.43
3 71.747 3.00 1.58313 59.4 43.00
4* 25.706 6.93 38.64
5 92.706 4.95 1.88300 40.8 38.40
6 -127.713 0.70 37.98
7 -97.467 2.50 1.49700 81.5 37.74
8 39.023 5.83 1.83481 42.7 34.40
9 -1070.546 3.79 33.54
10 46.333 5.98 1.83481 42.7 27.33
11 -47.248 1.90 1.54814 45.8 25.69
12 21.482 5.07 23.10
13 -53.687 1.40 1.65412 39.7 23.15
14 197.561 0.15 23.88
15 29.239 6.73 1.43387 95.1 25.17
16 -44.333 2.59 25.22
17 (Aperture) ∞ 7.21 24.21
18 -17.904 3.78 1.60311 60.6 23.58
19 -15.383 2.15 1.80518 25.4 24.59
20 -48.206 0.25 28.74
21 97.922 8.54 1.61800 63.3 31.70
22 -29.308 0.25 33.27
23* -162.434 5.28 1.80400 46.6 34.68
24 -36.488 38.80 36.15
Image plane ∞

Aspherical data 4th surface
K = 0.00000e+000 A 4=-5.57660e-006 A 6=-9.40593e-009
A 8= 5.84881e-012 A 10=-3.17028e-014

Surface 23
K = 0.00000e+000 A 4=-1.09975e-005 A 6=-1.48146e-009
A 8=-9.36205e-012 A 10=-5.31145e-015

Various data

Focal length 24.55
F number 1.45
Angle of view 41.39
Image height 21.64
Total lens length 129.11
BF 38.80

Entrance pupil position 29.97
Exit pupil position -56.16
Front principal point position 48.18
Rear principal point position 14.25

Single lens Data lens Start surface Focal length
1 1 -59.81
2 3 -70.39
3 5 61.48
4 7 -55.73
5 8 45.21
6 10 28.86
7 11 -26.68
8 13 -64.40
9 15 41.76
10 18 115.85
11 19 -28.90
12 21 37.46
13 23 57.46

(Numerical Example 4)
Unit mm

Surface data Surface number rd nd vd Effective diameter
1 131.189 10.84 1.48749 70.2 67.56
2 -264.579 0.90 65.84
3 53.910 9.80 1.49700 81.5 58.70
4 260.718 3.20 56.95
5 -623.694 3.80 1.83400 37.2 56.04
6 105.942 2.53 52.84
7 63.907 8.04 1.49 700 81.5 51.35
8 -609.143 0.20 50.27
9 27.722 3.23 1.71736 29.5 41.72
10 23.809 12.30 37.67
11 (aperture) ∞ 3.00 35.48
12 ∞ 0.70 1.48749 70.2 33.33
13 ∞ 0.50 33.00
14 -1002.290 5.00 1.84666 23.9 32.66
15 -65.695 1.78 1.72000 50.2 31.52
16 39.690 21.66 28.82
17 -34.937 2.72 1.74077 27.8 25.91
18 130.139 8.68 1.77250 49.6 30.42
19 -43.302 0.50 33.58
20 97.410 5.67 1.83400 37.2 37.12
21 -205.341 53.99 37.55
Image plane ∞

Various data

Focal length 130.98
F number 2.06
Angle of view 9.38
Image height 21.64
Total lens length 159.05
BF 53.99


Entrance pupil position 74.80
Exit pupil position -102.26
Front principal point position 95.99
Rear principal point position -76.99

Single lens Data lens Start surface Focal length
1 1 181.54
2 3 134.63
3 5 -108.33
4 7 116.84
5 9 -358.95
6 12 0.00
7 14 82.83
8 15 -34.12
9 17 -36.92
10 18 43.00
11 20 79.90

(Numerical Example 5)
Unit mm

Surface data Surface number rd nd vd Effective diameter
1 400.000 2.80 1.58313 59.4 52.58
2 40.544 6.91 45.50
3 606.181 2.30 1.58313 59.4 45.32
4 50.282 10.31 43.04
5 61.687 6.50 1.71300 53.9 43.03
6 -188.040 5.20 42.59
7 47.477 5.06 1.71300 53.9 35.38
8 -490.980 0.20 34.36
9 31.299 3.00 1.51633 64.1 31.66
10 25.382 9.27 29.20
11 -72.820 3.77 1.83481 42.7 27.77
12 -27.213 1.50 1.63980 34.5 27.70
13 -1242.161 3.70 26.64
14 (aperture) ∞ 7.07 25.33
15 -18.961 1.60 1.80518 25.4 24.41
16 759.560 3.30 1.83481 42.7 27.71
17* -65.346 0.20 28.81
18 -172.700 5.94 1.77250 49.6 29.37
19 -30.321 0.20 30.66
20 -160.598 6.81 1.77250 49.6 33.22
21 -32.418 38.65 34.86
Image plane ∞

Aspheric surface data surface 17
K = 2.39046e+000 A 4= 1.36838e-005 A 6= 3.28097e-010
A 8=-1.14450e-011

Various data focal length 34.30
F number 1.45
Angle of view 32.25
Image height 21.64
Total lens length 124.29
BF 38.65

Entrance pupil position 35.68
Exit pupil position -39.73
Front principal point position 54.97
Rear principal point position 4.36

Single lens Data lens Start surface Focal length
1 1 -77.59
2 3 -94.17
3 5 65.86
4 7 60.96
5 9 -314.29
6 11 50.16
7 12 -43.51
8 15 -22.95
9 16 72.21
10 18 46.76
11 20 51.39

(Numerical Example 6)
Unit mm

Surface data Surface number rd nd vd Effective diameter
1 131.189 10.84 1.48749 70.2 67.56
2 -264.579 0.90 65.84
3 53.910 9.80 1.49700 81.5 58.70
4 260.718 3.20 56.95
5 -623.694 3.80 1.83400 37.2 56.04
6 105.942 2.53 52.84
7 63.907 8.04 1.49 700 81.5 51.35
8 -609.143 0.20 50.27
9 27.722 3.23 1.71736 29.5 41.72
10 23.809 12.30 37.67
11 (aperture) ∞ 3.00 35.48
12 ∞ 0.70 1.48749 70.2 33.33
13 ∞ 0.50 33.00
14 -1002.290 5.00 1.84666 23.9 32.66
15 -65.695 1.78 1.72000 50.2 31.52
16 39.690 21.66 28.82
17 -34.937 2.72 1.74077 27.8 25.91
18 130.139 8.68 1.77250 49.6 30.42
19 -43.302 0.50 33.58
20 97.410 5.67 1.83400 37.2 37.12
21 -205.341 53.99 37.55
Image plane ∞

Various data

Focal length 130.98
F number 2.06
Angle of view 9.38
Image height 21.64
Total lens length 159.05
BF 53.99

Entrance pupil position 74.80
Exit pupil position -102.26
Front principal point position 95.99
Rear principal point position -76.99

Single lens Data lens Start surface Focal length
1 1 181.54
2 3 134.63
3 5 -108.33
4 7 116.84
5 9 -358.95
6 12 0.00
7 14 82.83
8 15 -34.12
9 17 -36.92
10 18 43.00
11 20 79.90

Table 1 shows numerical values corresponding to the conditional expressions (2) to (6) and the conditional expression (9) for each numerical example. FIG. 22 shows numerical values corresponding to the conditional expression (7) for each numerical example. 23, 24, 25, and 26 show numerical values corresponding to the conditional expression (8) for each numerical example. 22 to 26, the filter A corresponds to F1 and F2 of the first embodiment and F3 of the fourth embodiment. The filter B corresponds to F1 and F2 of the second embodiment and F1 and F2 of the fourth embodiment. The filter C corresponds to F1 and F2 in the third embodiment. The filter D corresponds to F1 and F2 in the fifth embodiment. The filter E corresponds to F1 and F2 in the sixth embodiment. The filter D does not satisfy the conditional expression (8).

Next, with reference to FIG. 27, an image pickup apparatus (camera system) including the photographing optical system (photographing lens) according to the present embodiment will be described. FIG. 27 is a configuration diagram of the image pickup apparatus 200 (single-lens reflex camera) according to the present embodiment.

The lens barrel 110 (interchangeable lens) has a photographing optical system 100 (optical system) as a photographing lens. The photographing optical system 100 is the photographing optical system according to any one of Examples 1 to 6. The taking optical system 100 is held by a lens barrel 110 that is a holding member.

Reference numeral 220 denotes a camera body (imaging device body). The camera body 220 includes a quick return mirror 203, a focusing screen 204, a penta roof prism 205, and an eyepiece lens 206. The quick return mirror 203 reflects upward the light flux formed via the photographing optical system 100. The focusing screen 204 is arranged at the image forming position of the photographing optical system 100. The penta roof prism 205 converts the reverse image formed on the focusing screen 204 into an erect image. The user can observe the erected image through the eyepiece lens 206. Reference numeral 207 denotes a photosensitive surface. On the photosensitive surface 207, a photoelectric conversion element (imaging element) such as a CCD sensor or a CMOS sensor that receives an image and a silver salt film are arranged. At the time of photographing, the quick return mirror 203 is retracted from the optical path, and the photographing optical system 100 forms an image (optical image) on the photosensitive surface 207. In this way, the image sensor photoelectrically converts the optical image formed by the photographing optical system 100 and outputs image data.

By applying the lens barrel 110 of this embodiment to the image pickup apparatus 200 such as a single-lens reflex camera, an optical device having high optical performance can be realized. Further, although the lens barrel 110 is an interchangeable lens configured to be attachable to and detachable from the camera body 220, this embodiment is also applicable to an image pickup apparatus in which the lens barrel 110 and the camera body 220 are integrally configured. Is. The lens barrel 110 can also be applied to a mirrorless single-lens reflex camera (mirrorless camera) without a quick return mirror.

In this way, by applying the taking optical system of each embodiment to an image pickup device such as a camera for photography, a video camera, a digital still camera, etc., an image pickup device capable of obtaining a good defocus image for a light flux of all angles of view. Can be realized. According to each of the embodiments, it is possible to provide an imaging optical system and an imaging device that can satisfactorily obtain an out-of-focus image of a light flux at all angles of view even when vignetting occurs.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof.

100 Photographing optical system F1 Transmittance distribution filter (first apodization filter)
F2 Transmittance distribution filter (second apodization filter)
SP aperture

Claims (17)

Aperture,
A first apodization filter arranged on the object side of the diaphragm,
A second apodization filter arranged on the image plane side of the diaphragm,
For both the first apodization filter and the second apodization filter, distances from the optical axis in the radial direction orthogonal to the optical axis are r1 and r2 (r1<r2), and only the distances r1 and r2 are from the optical axis. When the transmittances at distant positions are T(r1) and T(r2),
T(r1)≧T(r2)
Satisfy the relationship
The second apodization meridional light beam of the maximum angle of view in an open state the previous SL diaphragm and the region on the first apodization filter incident, meridional light beam of the maximum angle in the opened state of the aperture is incident an area on the filter, at least one of the photographing optical system, characterized in go and that contains a point on the optical axis. The photographing optical system according to claim 1, wherein the relationship between the transmittances T(r1) and T(r2) is satisfied in one cross section passing through the optical axis. The photographing optical system according to claim 1, wherein the relationship between the transmittances T(r1) and T(r2) is satisfied in a region symmetrical with respect to the optical axis. Regarding at least one of the first apodization filter and the second apodization filter, when the maximum transmittance within the effective diameter is T0 and the minimum transmittance within the effective diameter is T1,
T1/T0≦0.5
The photographing optical system according to any one of claims 1 to 3, wherein: The distance on the optical axis between the first apodization filter and the second apodization filter is e, and the distance from the surface apex of the lens surface closest to the object side of the photographing optical system to the paraxial image formation surface. When we say L,
e/L>0.1
The photographic optical system according to any one of claims 1 to 4, characterized in that: In the state where the diaphragm is opened, Hb is a point where a perpendicular line of the optical axis that passes through an intersection of an upper line of the most off-axis light beam and an upper line of the on-axis light beam intersects the optical axis, and an underline of the most off-axis light beam and the axis. Hf is a point at which a perpendicular line of the optical axis passing through an intersection with the underline of the upper light flux intersects with the optical axis, and on the optical axis between one of the first apodization filter and the second apodization filter and the diaphragm. The distance is dj (j=1, 2), and the light between the stop and the point near one of the first apodization filter and the second apodization filter on the optical axis of the points Hf and Hb. When the distance on the axis is Dj (j=1, 2),
-0.2<(dj-Dj)/L<0.3
(However, j=1, 2)
The photographing optical system according to any one of claims 1 to 5, characterized in that: When focusing at infinity, when the focal length of the photographing optical system is f (mm) and the open F value of the diaphragm is Fno,
10≦f/Fno≦75
The photographic optical system according to any one of claims 1 to 6, which satisfies the following condition. When the focal length of the photographing optical system is f (mm),
10≦f≦140
The photographic optical system according to any one of claims 1 to 7, characterized in that: Regarding at least one of the first apodization filter and the second apodization filter, a difference in transmittance in a wavelength range of 430 nm or more and 700 nm or less when compared at the same position is within 20%. Item 9. The photographing optical system according to any one of items 1 to 8. For at least one of the first apodization filter and the second apodization filter, when the effective diameter is rmax and the distance from the optical axis in the radial direction is r,
min(0.9,max(0,-1.6r+1))≤T(r/rmax)≤min(1,-5r+5.5)
The photographic optical system according to any one of claims 1 to 9, characterized in that: Regarding at least one of the first apodization filter and the second apodization filter, the effective diameter is rmax, the maximum transmittance within the effective diameter is T0, and the diameter at which the transmittance is T0/√e is r0×rmax. Then, within the range of r<0.8×rmax,
0.8×exp(−(1/2)×(r/(0.8×r0)) ² )≦T(r/rmax)≦1.2×exp(−(1/2)×(r/ (1.2*r0)) ² ) is satisfy|filled, The imaging optical system of any one of Claim 1 thru|or 10 characterized by the above-mentioned. With the diaphragm open,
In one of the first apodization filter and the second apodization filter, the transmittance of the upper line of the maximum field angle light flux is higher than the transmittance of the underline thereof,
12. The other of the first apodization filter and the second apodization filter, wherein the transmittance of the underline of the maximum angle of view light flux is higher than the transmittance of the upper line. Or the photographic optical system according to item 1. With the diaphragm open,
In one of the first apodization filter and the second apodization filter, the transmittance of the upper line of the meridional light flux is the maximum transmittance, the transmittance of the underline of the meridional light flux is the minimum transmittance,
In the other of the first apodization filter and the second apodization filter, the transmittance of the underline of the meridional light flux is the maximum transmittance, and the upper line of the meridional light flux is the minimum transmittance. Item 12. The photographing optical system according to item 12. When the image height is y and the maximum image height is Ymax in the state where the diaphragm is open, y=0 when the photographing optical system does not include the first apodization filter and the second apodization filter. The peripheral light amount ratio R at the image height y of 9.9Ymax is
R≦0.5
The photographing optical system according to any one of claims 1 to 13, characterized in that: A front group consisting of a lens arranged on the object side of the diaphragm;
A rear group consisting of lenses arranged on the image plane side of the diaphragm,
The first apodization filter is provided in the front group,
The photographing optical system according to any one of claims 1 to 14, wherein the second apodization filter is provided in the rear group. 16. The photographing optical system according to claim 1, further comprising a third apodization filter between the first apodization filter and the second apodization filter. A photographing optical system according to any one of claims 1 to 16,
An image pickup device comprising: an image pickup device that photoelectrically converts an optical image formed via the photographing optical system.