JP2020008823A - Color separation optical system and television camera using the same - Google Patents

Abstract

Provided is a color separation prism and a filter device that enable a special effect filter to be arranged in a television camera body without damaging a part or all of an existing ND filter, color temperature conversion filter, and the like.
By using a high refractive index glass for a prism 504a, one filter can be added to a conventional two-piece filter disk device without changing the distance (air conversion length) from a photographing lens mount surface to an image sensor surface. And a filter disk device 512a having three components.
[Selection diagram] FIG.

Description

  The present invention relates to a color separation optical system having a filter disk and a television camera using the same.

  2. Description of the Related Art Conventionally, in an imaging system such as a television camera system, two filter disks containing various filters such as a color temperature conversion filter and an ND filter used for imaging are arranged in the television camera body. However, when a special effect filter such as a cross filter or a soft focus filter is to be built in, some or all of the color temperature conversion filter and the ND filter in the filter disc are replaced with these special effect filters.

  FIG. 1 illustrates the “camera-side optical system” of “Interface between 2 / 3-type 4K sensor-equipped camera and lens” described in technical document ARIB TR-B37.

  FIG. 2 illustrates the glass unit 101 and the glass unit 102 illustrated in FIG. 1 as an example of a three-color separation prism optical system used in a television camera. Behind the imaging lens, an optical low-pass filter 201, a color temperature conversion filter 202, an ND filter 203, an IR cut filter 204, a color separation prism 205, a trimming filter 206, and an imaging device 207 are sequentially arranged.

  An optical low-pass filter 201, a color temperature conversion filter 202, an ND filter 203, and an IR cut filter 204 correspond to the glass unit 101 in FIG. 1, and the color separation prism 205 corresponds to the glass unit 102 in FIG. , A trimming filter 206.

  FIG. 2 shows a configuration in which a two-filter disk configuration including a color temperature conversion filter 202 and an ND filter 203 is arranged.

  FIG. 8 shows a state in which the ND filter disk is viewed from the imaging lens side, and four types of a transparent glass filter 801, an ND25 [%] filter 802, an ND6.3 [%] filter 803, and an ND1.6 [%] filter 804. This is an example in which filters are arranged.

  FIG. 12 shows a state in which the ND filter disk is viewed from the imaging lens side, and includes a transparent glass filter 1201, an ND25 [%] filter 1202, an ND12.5 [%] filter 1203, an ND6.3 [%] filter 1204, and ND1. This is an example in which five types of filters of 6 [%] filter 1205 are arranged.

  The shape of the color separation prism 205 shown in FIG. 2 is determined by the specifications such as the refractive index n and Fno of the glass material of the prism used, as described in JP-A-60-42701.

  As shown in FIG. 3, the color separation prism 312 includes a first prism, a second prism, and a third prism from the photographing lens 313 side, and an air gap 308 is provided between the first prism and the second prism. The second prism and the third prism are joined by bonding. The taking lens 313 collects a light beam from a subject (not shown) and guides the light beam to the color separation prism 312.

  The first prism has an incident surface 301 facing the photographing lens, and reflects light from the photographing lens incident from the incident surface 301 on the blue reflecting dichroic film applied to the transmitting surface 302, and reflects only blue light. Permeate the rest. The reflected blue light is totally reflected on the incident surface 301, exits the emission surface 305, and travels to the image sensor 309. The light transmitted through the transmission surface 302 passes through the air gap 308 and enters from the entrance surface 303 of the second prism.

  The red reflecting dichroic film provided on the transmission surface 304 of the second prism reflects only red light and transmits remaining green light. The reflected red light is totally reflected on the entrance surface 303 of the second prism in contact with the air gap 308, exits the exit surface 306, and travels toward the image sensor 310.

  The green light transmitted through the transmission surface 304 enters the third prism, exits the emission surface 307, and travels toward the image sensor 311. Thus, the color separation prism separates the light beam.

Here, assuming that the angle between the incident surface 301 of the first prism and the dichroic film surface 302 of the transmitting surface is α, and the angle between the incident surface 303 of the second prism and the dichroic film surface 304 of the transmitting surface is β. The following conditional expressions (1), (2), and (3) must be satisfied.

  However, conditional expression (1) is that the wavelength region light to be transmitted on the dichroic surface 302 is not totally reflected, and conditional expression (2) is that the wavelength region light reflected on the dichroic surface 302 is totally reflected on the incident surface 301. The conditional expression (3) is necessary for the wavelength region light reflected on the dichroic surface 304 to be totally reflected on the incident surface 303.

  Here, focusing on the angle α, the range in which the angle α can exist is determined from the refractive index of the glass material and Fno from the conditional expressions (1) and (2).

The graph of FIG. 4 illustrates this matter, and shows the relationship between Fno and the angle α using the refractive index ne of the glass material as a parameter.
For example, a graph 401 with the refractive index ne = 1.5 is a graph of the conditional expression (1), and a graph 402 is a graph of the conditional expression (2). From this graph, it can be seen that the range of the angle α that satisfies the conditional expressions (1) and (2) at the same time is limited to a range where Fno is substantially larger than F1.4, regardless of the refractive index ne of the glass material. . That is, in the color separation optical system constituted by three prism systems, the vicinity of F1.4 is the limit.

JP-A-10-271385 JP 2001-159705 A JP-A-60-42701

ARIB TR-B37 "Interface between camera and lens equipped with 2/3 type 4K sensor" Modern Electronic Information and Telecommunications Selection Book

  By changing the conventional two-filter disc device to a three-filter filter device, a special effect filter such as a cross filter or a soft focus filter can be used without damaging a part or all of a color temperature conversion filter, an ND filter, and the like. It is an object to dispose it on the main body.

Further, conventionally, when only one ND filter disk is used, the problem that the degree of freedom in selecting the ND filter and the color temperature conversion filter is insufficient is solved.

  Therefore, according to the present invention, the refractive index is as high as 1.70 or more (1.70 ≦ refractive index ≦ 1.75 in the standard of “Interface between 2/3 type 4K sensor-equipped camera and lens” of ARIB TR-B37). By using the refractive index glass, one filter disk device is added to the conventional two-disk filter disk device without changing the distance (air conversion length) from the photographing lens mount surface to the imaging device surface, and the three-disk filter disk device is used. To

  In the ARIB TR-B37 standard of “Interface between 2 / 3-type 4K sensor-equipped camera and lens”, the distance (air conversion length) from the imaging lens mount surface to the imaging element surface, that is, the air conversion length is defined. The flange back length Lf is 47.99 [mm] ≦ Lf ≦ 48.01 [mm] for a green light component prism, and the optical path length (glass length) Lp of the color separation prism is 33.0 ± 4.0. 0 [mm], that is, 29.0 [mm] ≦ Lp ≦ 37.0 [mm].

  Here, increasing the refractive index of the color separation prism means that when the optical path length of the color separation prism is fixed, the value obtained by dividing the optical path length by the refractive index, that is, the air conversion length becomes shorter, the filter disk becomes smaller. Additional space is created. For example, when the optical path length of the color separation prism is 33.0 [mm], the air conversion length is 21.71 [mm] for the refractive index ne = 1.52 and 19.41 for the refractive index ne = 1.70. [Mm]. By utilizing the difference of 2.30 [mm] of the air conversion length as a space for adding one filter disk, it is possible to configure three filter disks.

1.20 [mm] obtained by subtracting 1.10 [mm] of the air gap between the filter disks from the difference 2.30 [mm] of the air conversion length, and the length obtained by multiplying the refractive index 1.52 of the filter by 1.20 [mm]. 82 [mm] is the filter thickness of the filter disk to which one sheet is added.

  Thereby, the special effect filters such as the cross filter and the soft focus filter can be arranged on the television camera body without damaging a part or all of the color temperature conversion filter, the ND filter, and the like.

  In addition, a filter disk with an ND filter and a color temperature conversion filter can be added instead of the special effect filter disk, and the combination of two filters can be used to expand the freedom of selecting the ND filter and the color temperature conversion. it can.

  According to the present invention, by using a high-refractive-index prism, one sheet is added to the conventional two-filter disk structure without changing the distance (air conversion length) from the photographing lens mount surface to the image sensor surface, A color separation optical system having a three-filter disk configuration can be realized. Thereby, the special effect filters such as the cross filter and the soft focus filter can be arranged on the television camera body without damaging a part or all of the color temperature conversion filter and the ND filter.

  In addition, a filter disk with an ND filter and a color temperature conversion filter can be added instead of the special effect filter disk, and the combination of two filters can be used to expand the freedom of selecting the ND filter and the color temperature conversion. it can.

The figure which shows the relationship between the lens flange back length of a 2/3 type television camera, and a standard glass structure Configuration diagram of three-color separation prism optical system Prism diagram illustrating the relationship between Fno and apex angle of a three-color separation prism Graph showing total reflection conditions and air layer transmission conditions for explaining the relationship between Fno and apex angle of a three-color separation prism. (A) Schematic diagram of a camera system having a color separation optical system with three filter disks of the present invention. (B) Schematic diagram of a conventional camera system having a two-filter disc color separation optical system. Schematic configuration diagram of the color separation prism of the present invention Ghost development of the color separation prism of the present invention Schematic diagram of a conventional filter disk (with four types of filters) Schematic diagram of three filter disks of the present invention (four types of filters are arranged on each filter disk) Schematic diagram of two ND filter discs built in three filter discs of the present invention (four types of filters are arranged on each filter disc) ND filter density combination diagram with two ND filter disks built into three filter disks of the present invention (four types of filters are arranged on each filter disk) Schematic diagram of conventional filter disk (5 types of filters are arranged) Schematic diagram of three filter disks of the present invention (five types of filters are arranged on each filter disk) Schematic diagram of two ND filter discs built in three filter discs of the present invention (five types of filters are arranged on each filter disc) ND filter concentration combination diagram with two ND filter disks built into three filter disks of the present invention (five types of filters are arranged on each filter disk) Schematic diagram of two color temperature conversion filter disks incorporated in the three filter disks of the present invention (four types of filters are arranged on each filter disk). Combination diagram of color temperature conversion filter by two color temperature conversion filter disks built into three filter disks of the present invention (four types of filters are arranged on each filter disk)

  An embodiment according to the present invention will be described below in detail with reference to the drawings.

  First, a side view of a camera system (imaging apparatus) having a conventional two-filter disk color separation optical system is shown in FIG. In FIG. 5B, reference numeral 501b denotes a photographing lens, 502b denotes a television camera, and 503b denotes a lens mount surface. The main body of the television camera 502b contains an optical low-pass filter 507b and an IR cut filter 508b, and a turret-type two filter disk 511b of a color temperature conversion filter 509b and an ND filter 510b. A color separation prism 504b, a trimming filter 505b, and an image sensor 506b are arranged behind the two filter disks in the optical axis direction.

Next, FIG. 5A shows a side view of a camera system (imaging device) having a color separation optical system of a three-filter disk of the present invention.
In FIG. 5A, the distance (air) from the lens mount surface 503a of the photographing lens 501a to the image sensor surface 506a is increased by making the shape and glass length of the color separation prism the same and increasing the refractive index of the glass. Without changing the conversion length, one filter disk device is added to the conventional two-disk filter disk device to form a three-disk filter disk device 512a.

  In the ARIB TR-B37 standard of “Interface between a camera equipped with a 2 / 3-type 4K sensor and a lens”, the distance (air conversion length) from the imaging lens mount surface to the imaging element surface, that is, the air conversion length is defined. The flange back length Lf is 47.99 [mm] ≦ Lf ≦ 48.01 [mm] for a green light component prism, and the optical path length (glass length) Lp of the color separation prism is 33.0 ± 4.0. 0 [mm], that is, 29.0 [mm] ≦ Lp ≦ 37.0 [mm].

  Here, increasing the refractive index of the color separation prism means that when the optical path length of the color separation prism is fixed, the value obtained by dividing the optical path length by the refractive index, that is, the air conversion length becomes shorter, the filter disk becomes smaller. Additional space is created. For example, when the optical path length of the color separation prism is 33.0 [mm], the air conversion length is 21.71 [mm] for the refractive index ne = 1.52 and 19.41 for the refractive index ne = 1.70. [Mm]. The difference of 2.30 [mm] of the air conversion length is used as a space for adding one filter disk, thereby forming three filter disks.

1.20 [mm] obtained by subtracting 1.10 [mm] of the air gap between the filter disks from the difference 2.30 [mm] of the air conversion length, and the length obtained by multiplying the refractive index 1.52 of the filter by 1.20 [mm]. 82 [mm] is the filter thickness of the filter disk to which one sheet is added.

  Setting the refractive index ne = 1.70 is equivalent to the optical path length and prism shape of the color separation prism configured with the refractive index ne = 1.52. Therefore, the color separation prism unit is replaced with a conventional one. Is possible. This indicates that the positional relationship between the color separation prism section and the image sensor is unchanged, and does not affect the internal structure of the image sensor substrate, electronic circuit, and the like in the television camera body.

  FIG. 4 shows that even if a glass material having a refractive index of 1.70 ≦ ne ≦ 1.75 is selected for the color separation prism, the Fno limit value of the color separation prism composed of three prisms is the refractive index ne = As in the case of 1.52, it shows that it is almost F1.4. For example, a graph 403 of the refractive index ne = 1.7 is a graph of the conditional expression (1), and a graph 404 is a graph of the conditional expression (2). From this graph, it can be seen that the range of the angle α that satisfies the conditional expressions (1) and (2) at the same time is limited to a range where Fno is substantially larger than F1.4 regardless of the refractive index of the glass material.

  Here, based on conditional expressions (1) and (2), the vertex angle α of the first prism is 26.5 degrees, and based on conditional expression (3), the vertex angle β of the second prism is 39.75 degrees. Is desirable.

  For the Abbe number νe of the color separation prism, a glass material of 42.5 ≦ νe ≦ 50.5 is selected based on the standard of ARIB TR-B37 “Interface between a camera equipped with a 2 / 3-type 4K sensor and a lens”. I do.

  Thus, the special effect filter disk 511a such as a cross filter or a soft focus filter can be arranged on the television camera body without damaging a part or all of the color temperature conversion filter 509a and the ND filter 510a.

  FIG. 9 shows a state in which three filter discs each including four types of filters are viewed from the photographing lens side, and the three filter discs are color temperature conversion filter discs 901, ND filter discs 902, This is an example when the special effect filter disk 903 is assigned.

  The color temperature conversion filter disk 901 is an example in which four types of filters, a transparent glass filter 901a, a color temperature conversion A filter 901b, a color temperature conversion B filter 901c, and a color temperature conversion C filter 901d are arranged.

  The ND filter disk 902 is an example in which four types of filters, a transparent glass filter 902a, an ND-A filter 902b, an ND-B filter 902c, and an ND-C filter 902d, are arranged.

  The special effect filter disk 903 is an example in which four types of filters, a transparent glass filter 903a, a special effect A filter 903b, a special effect B filter 903c, and a special effect C filter 903d are arranged.

  In addition, a filter disk with an ND filter and a color temperature conversion filter can be added instead of the special effect filter disk, and the combination of two filters can be used to expand the freedom of selecting the ND filter and the color temperature conversion. it can.

  In addition, the ND filter and the color temperature conversion filter are also arranged in the special effect filter disk, and a two-filter disk configuration can be used to increase the degree of freedom of the combination of the ND filter and the color temperature conversion filter.

  FIG. 10 shows an example of a built-in ND filter disk 1001 and ND filter disk 1002 when two of the three filter disks are used for an ND filter.

  The ND filter disk 1001 is an example in which four types of filters of a transparent glass filter 1001a, an ND-A filter 1001b, an ND-B filter 1001c, and an ND-C filter 1001d are arranged.

  The ND filter disk 1002 is an example in which four types of filters, a transparent glass filter 1002a, an ND-E filter 1002b, an ND-F filter 1002c, and an ND-G filter 1002d, are arranged. By using filters having different ND densities in combination, 15 types of ND filters having different densities can be realized as shown in FIG.

  FIG. 16 shows an example of a built-in color temperature conversion filter disk 1601 and a color temperature conversion filter disk 1602 when two of the three filter disks are used for a color temperature conversion filter.

  The color temperature conversion filter disk 1601 is an example in which four types of filters, a transparent glass filter 1601a, a CC-3400K filter 1601b, a CC-4300K filter 1601c, and a CC-5800K filter 1601d, are arranged.

  The color temperature conversion filter disk 1602 is an example in which four types of filters of a transparent glass filter 1602a, a CC-3700K filter 1602b, a CC-2300K filter 1602c, and a CC-1900K filter 1602d are arranged. By using filters having different color temperatures in combination, as shown in FIG. 17, 15 different color temperature conversion filters can be realized.

  Generally, a television camera is designed to express a normal color with respect to a light source having a color temperature of 3200 Kelvin of studio lighting. Therefore, when the color temperature changes, a color temperature conversion filter that converts the color temperature to 3200 Kelvin is used. use.

  In FIG. 17, for example, CC-5800K means a filter that converts the color temperature of daytime sunlight, 5800 Kelvin, into the color temperature of studio lighting of 3,200 Kelvin. CC-1900K means a filter that converts 1900 Kelvin, which is the color temperature immediately before sunrise and sunset, to 3200 Kelvin, which is the color temperature of studio lighting. Further, for example, by combining the filters of CC-5800K and CC-3700K, a filter that converts 7700 Kelvin, which is a color temperature of a sunny shade, to 3200 Kelvin of studio lighting color temperature can be realized.

  FIG. 13 shows a state in which three filter discs each including five types of filters are viewed from the photographing lens side, and the three filter discs are color temperature conversion filter discs 1301, ND filter discs 1302, This is an example of a case where a special effect filter disk 1303 is assigned.

  The color temperature conversion filter disk 1301 is an example in which five types of filters, a transparent glass filter 1301a, a color temperature conversion A filter 1301b, a color temperature conversion B filter 1301c, a color temperature conversion C filter 1301d, and a color temperature conversion D filter 1301e, are arranged. is there.

  The ND filter disk 1302 is an example in which five types of filters of a transparent glass filter 1302a, an ND-A filter 1302b, an ND-B filter 1302c, an ND-C filter 1302d, and an ND-D filter 1302e are arranged.

  The special effect filter disk 1303 is an example in which five types of filters, a transparent glass filter 1303a, a special effect A filter 1303b, a special effect B filter 1303c, a special effect C filter 1303d, and a special effect D filter 1303e are arranged.

  In addition, a filter disk with an ND filter and a color temperature conversion filter can be added instead of the special effect filter disk, and the combination of two filters can be used to expand the freedom of selecting the ND filter and the color temperature conversion. it can.

  In addition, the ND filter and the color temperature conversion filter are also arranged in the special effect filter disk, and a two-filter disk configuration can be used to increase the degree of freedom of the combination of the ND filter and the color temperature conversion filter.

  FIG. 14 shows an example of a built-in ND filter disk 1401 and ND filter disk 1402 when two of the three filter disks are used for an ND filter.

  The ND filter disk 1401 is an example in which five types of filters of a transparent glass filter 1401a, an ND-A filter 1401b, an ND-B filter 1401c, an ND-C filter 1401d, and an ND-D filter 1401e are arranged.

  The ND filter disk 1402 is an example in which five types of filters, a transparent glass filter 1402a, an ND-E filter 1402b, an ND-F filter 1402c, an ND-G filter 1402d, and an ND-H filter 1402e, are arranged. By using filters having different ND densities in combination, 24 types of ND filters having different densities can be realized as shown in FIG.

  Similarly, as for the color temperature conversion filters, 24 types of color temperature conversion filters having different color temperatures can be realized by combining the filters between the two color temperature conversion filter disks in which five types of filters are arranged.

  FIGS. 6A and 6B show the shape of the color separation prism when the refractive index ne = 1.70 and the refractive index ne = 1.52 when the same air-equivalent length is used. The optical path length when the air separation length of the color separation prism is 19.41 [mm] and the refractive index ne = 1.70 is the length obtained by multiplying the refractive index ne = 1.70 by the air conversion length 19.41. Of 33.0 [mm]. Similarly, when the air separation length of the color separation prism is 19.41 [mm] and the refractive index ne = 1.52, the optical path length is obtained by multiplying the refractive index ne = 1.52 by the air conversion length 19.41. 29.5 [mm].

  FIGS. 7A and 7B show the refractive index ne = 1.70 and the refractive index ne = 1.52 when the same air-converted length shown in FIGS. 6A and 6B is used. FIG. 9 is a development view for judging a state of occurrence of a ghost due to internal reflection of the first prism for the color separation prism of FIG. When the refractive index ne = 1.70 and the optical path length is 33.0 [mm], the ghost ray 703a due to the internal reflection of the first prism 701a and the refractive index ne = 1.52 and the optical path length is 29.5 [mm] A ghost light beam 703b due to internal reflection of one prism 701b is shown. As can be seen from this figure, in the case of the refractive index ne = 1.70 and the optical path length of 33.0 [mm], the ghost ray 703a is out of the image sensor 702a, whereas the refractive index ne = 1. .52 and an optical path length of 29.5 [mm] indicate that the ghost light beam 703b reaches the surface of the image sensor 702b. That is, the refractive index ne = 1.70 indicates that it is superior to the ghost as compared with the refractive index ne = 1.52.

  As described above, by using the high-refractive-index prism of the present invention, it is possible to reduce the distance (air-equivalent length) from the photographing lens mount surface to the image sensor surface by changing the conventional two-filter disk configuration. With the addition of three, a color separation optical system having a three-filter disk configuration can be realized. As described above, the present invention can be applied to the addition of a special effect filter disk such as a cross filter or a soft focus filter to the conventional two filter disk configuration having a color temperature conversion filter and an ND filter.

  In addition, a filter disk with an ND filter and a color temperature conversion filter is added instead of the special effect filter disk, and it is used in combination as a two-piece configuration to improve the freedom of selection of the ND filter and the color temperature conversion. it can.

Reference Signs List 101 glass part 102 glass part 103 photographing lens 104 lens mount surface 105 image sensor surface 106 flange back length 201 optical low-pass filter 202 color temperature conversion filter 203 ND filter 204 IR cut filter 205 color separation prism 206 trimming filter 207 image sensor 301 first Prism entrance surface 302 Dichroic film surface 303 of the transmission surface of the first prism 303 Incident surface 304 of the second prism Dichroic film surface 305 of the transmission surface of the second prism 305 Exit surface 306 of the first prism 306 Exit surface 307 of the second prism Emission surface 308 of prism Air gap 309 Blue light image sensor 310 Red light image sensor 311 Green light image sensor 312 Color separation prism 313 Photo lens 401 Graph 402 of conditional expression (1) at a refractive index of 1.5 Graph 403 of conditional expression (2) at a refractive index of 1.5 Graph 404 of conditional expression (1) at a refractive index of 1.7 Graph 501a of conditional expression (2) at a refractive index of 1.7 When three filter disks The photographing lens 502a of the TV camera 503a with three filter discs The lens mount surface 504a with three filter discs The color separation prism 505a with three filter discs The trimming filter 506a with three filter discs The image sensor with three filter discs 507a Optical low-pass filter with 3 filter discs 508a IR cut filter with 3 filter discs 509a Color temperature conversion filter with 3 filter discs 510a ND filter with 3 filter discs 511a Special effect filter with 3 filter discs Filter 512a Three filter disk part 501b Shooting lens 502b with two filter disks TV camera 503b with two filter disks Lens mount surface 504b with two filter disks Color separation prism 505b with two filter disks 505b Two filter disks Trimming filter 506b Image sensor 507b with two filter discs Optical low pass filter 508b with two filter discs IR cut filter 509b with two filter discs Color temperature conversion filter 510b with two filter discs 510b with two filter discs ND filter 511b Two filter disk unit 601a First prism 602a with a refractive index of 1.70 Second prism 603a with a refractive index of 1.70 Third prism 604a at 1.70 hour First image sensor 605a at 1.70 refractive index Second image sensor 606a at 1.70 hour refractive index Third image sensor 601b at 1.70 hour refractive index Refractive index 1.52 The first prism 602b at the time The second prism 603b at the refractive index of 1.52 The third prism 604b at the refractive index of 1.52 The first image sensor 605b at the refractive index of 1.52 The second imaging at the refractive index of 1.52 Element 606b Third imaging element 701a with a refractive index of 1.52 First prism 702a with a refractive index of 1.70 First imaging element 703a with a refractive index of 1.70 Ghost ray 701b with a refractive index of 1.70 Refractive index 1 0.51st prism 702b First image sensor 703b with 1.52 refractive index Ghost light 801 with 1.52 refractive index Transparent glass filter 802 ND25 [%] filter 80 3 ND6.3 [%] filter 804 ND1.6 [%] filter 901 Color temperature conversion filter disk 901a Clear glass filter 901b Color temperature conversion A filter 901c Color temperature conversion B filter 901d Color temperature conversion C filter 902 ND filter disk 902a Clear Glass filter 902b ND-A [%] filter 902c ND-B [%] filter 902d ND-C [%] filter 903 Special effect filter disc 903a Transparent glass filter 903b Special effect A filter 903c Special effect B filter 903d Special effect C filter 1001 ND filter disc 1001a Transparent glass filter 1001b ND-A [%] filter 1001c ND-B [%] filter 1001d ND- C [%] filter 1002 ND filter disc 1002a transparent glass filter 1002b ND-E [%] filter 1002c ND-F [%] filter 1002d ND-G [%] filter 1201 transparent glass filter 1202 ND25 [%] filter 1203 ND12. 5 [%] filter 1204 ND6.3 [%] filter 1205 ND1.6 [%] filter 1301 Color temperature conversion filter disk 1301a Transparent glass filter 1301b Color temperature conversion A filter 1301c Color temperature conversion B filter 1301d Color temperature conversion C filter 1301e Color temperature conversion D filter 1302 ND filter disk 1302a Transparent glass filter 1302b ND-A [%] filter 1302c ND-B [ ] Filter 1302d ND-C [%] filter 1302e ND-D [%] filter 1303 Special effect filter disc 1303a Clear glass filter 1303b Special effect A filter 1303c Special effect B filter 1303d Special effect C filter 1303e Special effect D filter 1401 ND filter Disc 1401a Transparent glass filter 1401b ND-A [%] filter 1401c ND-B [%] filter 1401d ND-C [%] filter 1401e ND-D [%] filter 1402 ND filter disc 1402a Transparent glass filter 1402b ND-E [ %] Filter 1402c ND-F [%] filter 1402d ND-G [%] filter 1402e ND-H [%] filter -1601 Color temperature conversion filter disk 1601a Transparent glass filter 1601b CC-3400K filter 1601c CC-4300K filter 1601d CC-5800K filter 1602 Color temperature conversion filter disk 1602a Transparent glass filter 1602b CC-3700K filter 1602c CC-2300K filter 1602d CC-1900K filter

Claims (18)

  A color separation prism disposed between a photographic lens and an image sensor, wherein the refractive index ne of the color separation prism is 1.7 or more, and the first prism and the second prism are arranged from the photographic lens side. A color separation characterized by comprising three prisms in the order of a prism and a third prism to separate three colors, wherein the first and second prisms each have three surfaces of an entrance surface, an exit surface and a transmission surface. Optical system.   The color separation optical system according to claim 1, wherein a refractive index ne of the color separation prism satisfies 1.70 ≦ ne ≦ 1.75.   3. The color separation optical system according to claim 1, wherein an Abbe number ve of the color separation prism satisfies 42.5≤ve≤50.5.   4. The color separation optical system according to claim 1, wherein an optical path length Lp of the color separation prism satisfies 29.0 [mm] ≦ Lp ≦ 37.0 [mm].   The color separation optical system according to any one of claims 1 to 4, wherein a vertex angle between the incident surface and the transmission surface of the first prism of the color separation prism is 26.5 degrees.   The color separation optical system according to any one of claims 1 to 5, wherein a vertex angle between the incident surface and the transmission surface of the second prism of the color separation prism is 39.75 degrees.   The filter according to any one of claims 1 to 6, wherein the color separation prism has a high refractive index, thereby reducing the air-converted length of the color-separating prism and without changing the flange back length defined by the air-converted length. A color separation optical system characterized by adding one disk.   8. The color separation optical system according to claim 7, wherein one filter disk is added without changing the flange back length defined by the air conversion length. A color separation optical system, wherein a back length Lf is a reference green component prism and satisfies 47.99 [mm] ≦ Lf ≦ 48.01 [mm].   The color separation optical system according to claim 7, wherein the filter disk according to claim 7 has a three-piece configuration by adding one filter disk.   10. A color separation optical system, wherein two of the three filter discs according to claim 9 are constituted by discs having an ND filter.   10. A color separation optical system, wherein two of the three filter discs according to claim 9 are constituted by discs having a color temperature conversion filter.   10. The color separation optical system according to claim 9, wherein the three-filter disc includes a disc having a color temperature conversion filter, a disc having an ND filter, and a disc having a special effect filter.   At least one of the three filter disks according to claim 9 is configured by two or more different types of filters among a color temperature conversion filter, an ND filter, and a special effect filter. Color separation optical system.   14. The color separation optics according to claim 7, wherein a filter thickness t of the one additional filter disk according to claim 7 is 1.5 [mm] ≦ t ≦ 2.5 [mm]. system.   15. The degree of freedom in selecting a filter density is increased by using an ND filter in combination between two or more filter disks among the plurality of filter disks according to claim 7. A color separation optical system.   The color temperature conversion can be freely selected by using a color temperature conversion filter in combination between two or more filter disks among the plurality of filter disks according to any one of claims 7 to 14. A color separation optical system characterized by widening the degree.   17. The color separation optical system according to claim 7, wherein each of the filter disks according to claim 7 includes four or five filters.   A television camera and a television camera system incorporating the color separation optical system according to any one of claims 1 to 17.