WO2019197528A1

WO2019197528A1 - Compact lens

Info

Publication number: WO2019197528A1
Application number: PCT/EP2019/059243
Authority: WO
Inventors: Henning Mehnert; Thomas Steinich
Original assignee: Carl Zeiss Ag
Priority date: 2018-04-13
Filing date: 2019-04-11
Publication date: 2019-10-17
Also published as: DE102018108818A1

Abstract

A lens, in particular for a mirrorless system camera, is provided, wherein the lens (1) comprises a first lens element (7) having positive refractive power, a second lens element (8) having negative refractive power, a third lens element (9) having positive refractive power and a fourth lens element (10) having negative refractive power, wherein the lens elements (7-10) are arranged one after another in the stated order proceeding from the object side along an optical axis (OA) of the lens (1), wherein the first and second lens elements (7, 8) form a first optical unit group (11) having positive refractive power and the third and fourth lens elements (9, 10) form a second optical unit group (12) having positive refractive power, wherein a first stop (13) is arranged between the second and third lens elements (8, 9), and the optical unit groups (11, 12) are displaceable independently of one another, at least one of the lens elements (7-10) is displaceable independently of the other lens elements (7-10) and/or the first stop (13) is displaceable independently of the other lens elements (7-10) along the optical axis (OA) in order to change the focus position and/or the imaging performance.

Description

Compact lens

The present invention relates to a lens, in particular for a mirrorless

System camera. Furthermore, the invention relates to a camera and an optical system, which includes the lens, as well as a use of the lens in different areas.

As compared to SLR cameras in a mirrorless system camera no

Folding mirror is more, in mirrorless system cameras, the focal distance (the distance between the lens of the lens, which is closest to the image sensor, and the image sensor) is lower than in SLR cameras.

It is therefore intended to provide an objective, in particular for a mirrorless system camera, that takes into account this smaller focal length, is as compact as possible and at the same time provides good imaging properties. Furthermore, a mirrorless system camera is to be provided with such a lens.

The invention is defined in independent claims 1, 15, 17 and 18. Advantageous embodiments are specified in the dependent claims.

The objective according to the invention, in particular for a mirrorless system camera, has a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power and a fourth lens with negative refractive power, wherein the lenses in the stated order, starting from the Object side along an optical axis of the lens are arranged one behind the other. The first and second lenses form a first one

Optical group with positive refractive power. The third and fourth lenses form a second optical group with likewise positive refractive power. Disposed between the second and third lenses is a first aperture, the optical groups being independently displaceable, at least one of the lenses independent of the other lenses, and / or the first aperture being displaceable independently of the other lenses along the optical axis about the focus position and / or to change the imaging performance.

With this structure, a very compact objective with good imaging properties can be provided. In particular, the lens may have few lenses (eg, just the four lenses), making the lens compact and lightweight can be. The lenses can have a small lens diameter, which in turn can lead to a reduction in size and weight.

The change of the imaging performance can in particular improve the

Be picture performance. The imaging performance of the objective is understood to mean, in particular, the general ability of the objective to provide an image (or image) of specific quality or quality. The imaging performance is e.g. the higher the lower one or more aberrations, e.g. spherical aberration, astigmatism, coma, field curvature, distortion, lateral chromatic aberration, longitudinal chromatic aberration and / or Gaussian error.

The displaceability of at least two elements of an objective group comprising the lenses, the optics groups and the first diaphragm can in particular be predetermined such that they (for example the two optical groups) are always different in the same direction only

Routes are displaced.

The displaceability of the two optical groups can be provided in particular such that the distance by which the first optical group is shifted to change from a first to a second focus position, is greater than the distance to which the second optical group to change from the first to the second Focusing position is moved.

In the objective according to the invention, at least one of the boundary surfaces of the lenses of the first optical group and / or at least one of the boundary surfaces of the lenses of the second optical group may be aspherically curved. Of course, it is also possible for a plurality of boundary surfaces of the lenses of the first optical group and a plurality of boundary surfaces of the lenses of the second

Optics group be aspherical curved. It is advantageous, for example, if a

Boundary surface of the lenses of the first optical group and two interfaces of the lenses of the second optical group are aspherically curved. An aspherically curved interface is preferably a rotationally symmetric aspherical interface.

The remaining boundary surfaces of the lenses are preferably spherically curved.

The two optical groups are in particular designed such that the respective two lenses are arranged at a distance from one another and their spacing can not be changed. It can also be said that the two optical groups can be free from cemented interfaces.

The first diaphragm (which is, for example, an aperture stop) may be part of the first or the second optical group and with this along the optical axis to be displaced. In particular, the distance between the first diaphragm and the third lens can not be changed. Furthermore, a second diaphragm can be arranged in the objective for optimizing the imaging performance. In the embodiment to be presented, the second diaphragm is designed as a comblade end and is the component of the second optical group and can be displaced along the optical axis with it. The distance of the coma end to the third lens may be changeable or not changeable. The Komablende can also belong to the first optical group. Furthermore, in addition to at least one of the lenses, in addition to at least one of the optical groups and / or next to the first diaphragm, a second or further diaphragm may be arranged.

The aperture diaphragm can be designed such that its diameter can be changed. The

Comablende is preferably designed so that its diameter is not changeable. Of course, the first aperture, the second aperture, and any further aperture may be formed either with changeable diameter or non-changeable diameter.

Furthermore, the objective according to the invention can be designed with a fixed focal length and the focal length can be chosen so that in a state of the objective mounted on the system camera having an image sensor, the ratio of intercept, that of the distance of the image sensor facing the interface of the fourth lens to the image sensor of the

System camera, the following inequality is satisfied: 0.2 <focal length / focal length <0.55.

In particular, the following inequality can be satisfied: 0.2 <focal length / focal length <0.4.

The lens may be designed so that half the diagonal angle of view is greater than or equal to 20 ° and less than or equal to 30 °.

The objective may include a first actuator for moving the first optical group and a second actuator for moving the second optical group and a control unit for

Control of the actuators, wherein the control unit always controls the actuators to change the focus position so that both optical groups are moved only in the same direction but by different distances. Thus, both optics groups are moved either to the image sensor or away from the image sensor.

The lens may have an actuator for moving the corresponding element of the lens group for each moving element of a lens group comprising the lenses, the optical groups and the first diaphragm, wherein the control unit or the actuators for changing the focus position and / or the Imaging performance. The objective can be configured such that the possible positions of the two optical groups are stored in a memory (for example in a memory of the control unit) and the control unit carries out the corresponding shift for changing the focal position based thereon.

The lenses of the objective according to the invention can be designed as glass lenses or plastic lenses.

The objective according to the invention can be designed such that it has exactly four lenses.

Furthermore, a camera (in particular a mirrorless system camera) with an objective according to the invention (including all further developments) and an image sensor is provided.

The mirrorless system camera is characterized in particular in that the area between the objective and the image sensor is free from a folding mirror (or a fold-away mirror), as is provided, for example, in the case of SLR cameras. Thus, no folding mirror is provided between the lens and the image sensor. Alternatively, if needed, the lens may be coupled to a SLR camera by means of a mating adapter. In this case, the adapter may have an optical arrangement with additional optical elements, such as e.g. Lenses, mirrors (including dichroic), prisms, apertures and / or diffractive optical elements include.

It is understood that the features mentioned above and those yet to be explained not only in the specified combinations, but also in others

Combinations or alone can be used without departing from the scope of the present invention.

The invention will be explained in more detail by means of embodiments with reference to the accompanying drawings, which also disclose features essential to the invention. These embodiments are merely illustrative and are not to be construed as limiting. For example, a description of one

Embodiment with a plurality of elements or components not to be construed as that all these elements or components are necessary for implementation. Rather, other embodiments may include alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of various embodiments may be combined with each other unless otherwise specified. Modifications and modifications, which are described for one of the embodiments may also be applicable to other embodiments. To avoid repetition, the same or corresponding elements in different figures are denoted by the same reference numerals and not explained several times. From the figures show:

1 shows a schematic view of a mirrorless system camera 3 according to the invention with an objective 1 according to the invention;

FIG. 2 shows a schematic lens section of the objective 1 according to the invention, wherein the objective 1 is focused to infinity; FIG.

3 shows a sectional view of the objective 1 according to the invention in the same way as in FIG. 2, wherein the objective 1 is focused in the near range; Fig. 4 is a diagram for explaining the field curvature of the invention

Objektivsl for the focus position shown in Figure 2;

5 shows a diagram for explaining the distortion of the objective 1 according to the invention for the focus position shown in FIG. 2;

Fig. 6 is a diagram for explaining the spherical aberration of the objective 1 according to the invention for the focus position shown in Fig. 2;

7 shows a diagram for explaining the image curvature of the objective 1 according to the invention for the focal position shown in FIG. 3;

8 is a diagram for explaining the distortion of the objective 1 according to the invention for the focus position shown in FIG. 3; 9 is a diagram for explaining the spherical aberration of the objective 1 according to the invention for the focus position shown in FIG. 3;

10 shows a schematic lens section of the objective 1 according to the invention in accordance with a further exemplary embodiment, wherein the objective 1 is focused to infinity; 11 shows a schematic view of a mirrorless system camera 3 according to the invention with a further embodiment of the objective 1 according to the invention; 12 shows a schematic view of a mirrorless system camera 3 according to the invention with a further embodiment of the objective 1 according to the invention;

13 shows a schematic view of a mirrorless system camera 3 according to the invention with a further embodiment of the objective 1 according to the invention;

14 shows a sectional view of a further embodiment of the objective 1 according to the invention in the same way as in the representation according to FIG. 2;

FIG. 15 is a sectional view of a further embodiment of the objective 1 according to the invention in the same way as in the representation according to FIG. 2; FIG.

Fig. 16 is a diagram for explaining the field curvature of the invention

Lens 1 of Fig. 15;

Fig. 17 is a diagram for explaining the distortion of the lens 1 according to the invention shown in FIG. 15, and

18 is a diagram for explaining the spherical aberration of the objective 1 according to the invention shown in FIG. 15.

In the exemplary embodiment shown in FIG. 1, an objective 1 according to the invention is mounted on a housing 2 of a mirrorless system camera 3. On the top of the housing 2, a trigger 4 and at the back of a screen 5 is arranged. In the housing 2, a schematically indicated image sensor 6 is arranged.

In the mirrorless system camera 3 no folding mirror is no longer provided between the lens 1 and the image sensor 6, as is the case with SLR cameras, so that the mirrorless system camera 3 no longer has an optical viewfinder. The function of the viewfinder is realized via the screen 5, which represents the image of the image sensor 6. Due to the omission of the folding mirror, the depth of the mirrorless system camera 3 is smaller than in a single-lens reflex camera, so that this can be taken into account in the design of lenses for mirrorless system cameras 3.

FIG. 2 shows a schematic lens section of the objective 1 for focusing adjustment infinite. As can be seen from the illustration in FIG. 2, the objective 1 has a first, a second, a third and a fourth lens 7, 8, 9, 10 which, in this order, proceed from the object side along an optical axis OA of the Lens 1 are arranged one behind the other.

The first and third lenses 7, 9 each have positive refractive power and the second and fourth lenses

8, 10 each have negative refractive power.

The first and second lenses 7, 8 are arranged at a distance from each other and form a first optical group 1 1, which is displaceable along the optical axis OA, wherein the distance between the two lenses 7, 8 remains constant. The third and fourth lenses 9, 10 form a second optical group 12 and are spaced from each other. The second optical group 12 is slidably disposed along the optical axis OA, wherein the distance of the third and fourth lens

9, 10 remains constant. Between the second and third lenses 8 and 9 is a

Aperture aperture 13 with adjustable diameter and a coma end 14 arranged with a constant diameter.

The aperture 13 is spaced from the coma end 14 and the coma end 14 is spaced from the third lens 9. Both the aperture stop 13 and the coma end 14 are part of the second optical group 12 and are also moved during the movement of the second optical group 12, the spacings of the aperture stop 13 and the coma end 14 of the third lens 9 remaining constant.

Both the first optical group 1 1 and the second optical group 12 each have positive refractive power.

The four lenses 7 - 10 each have two interfaces which, starting from the object side along the optical axis OA to the image sensor 6, are denoted by the reference symbols G1, G2,... G8. The boundary surface G4 of the second lens 8 and both boundary surfaces G7 and G8 of the fourth lens 10 are each aspherically curved. The remaining interfaces G1, G2,

G3, G5 and G6 are each spherically curved.

In the following Table 1, the distances of the interfaces G1 -G8, the apertures 13, 14 relative to the sensor 6 along the optical axis OA and the radii of curvature and the refractive indices and the Abbe numbers are given. Alternatively, the lenses can be made, for example, from the following materials: polystyrene, polyvinyl acetate, polypropylene,

Polycarbonate, polymethyl methacrylate or cycloolefin copolymer can be produced. Table 1 :

In the following tables for the aspherically curved interfaces G4, G7 and G8, the values of the coefficients a of the aspheric equation are

where z is the fleas of the asphere, c is the curvature (at the vertex), r is the radial distance, and ai are aspheric coefficients. All coefficients ai not given in the tables are zero.

Area G4:

Area G7:

Area G8:

The objective 1 has a fixed focal length, which is chosen in particular such that half the diagonal angle of view is less than or equal to 30 ° and greater than or equal to 20 °.

The described optical construction is chosen such that the ratio of the intersecting distance S (distance of the interface G8 from the image sensor 6 along the optical axis OA) to the

Focal length meets the following condition:

0.2 <focal length / focal length <0.55.

In particular, the following condition can be met:

0.2 <focal length / focal length <0.4.

In the position of the two optical groups 1 1 and 12 shown in FIG. 2, this is

Objective 1 of the invention focused to infinity. In order to allow focusing for shorter distances, the two optical groups 11 and 12 are moved along the optical axis OA in the same direction. However, the two optical groups 11 and 12 are not moved by the same distance, but by different distances.

For moving the optical groups 11, 12, two actuators 15, 16 are provided in the lens 1, wherein the first actuator 15 moves the first optical group 1 1 and the second actuator 16 moves the second optical group 12. The two actuators 15, 16 are controlled by means of a control unit 17. The control unit 17 can be arranged in the objective 1 or in the camera housing 2.

In order to refocus from the focusing to infinity shown in FIG. 2 into the near range (in this case the distance from the objective 1 which is the lowest in which it can still be sharply imaged, for example up to 1: 8), both optical groups 11 and 12 along the optical axis OA away from the image sensor 6. The first optics group will be here

described embodiment by 7.05 mm and the second optical group 12 is hereby shifted by 5.69 mm. The image sensor 6 is here as a small image sensor with a

Semi-diagonal of 21, 63 mm formed.

The maximum length of the first interface G1 to the image sensor 6 is in the focus position to infinity according to FIG. 2 and is 49.8 mm in the embodiment described here. The minimum cutting distance S is in the focus position shown in Fig. 3 and is 18.2 mm.

The performance of the objective according to the invention is excellent, as shown by the field curvature diagram (Figure 4), distortion (Figure 5) and spherical aberration (Figure 6) for the infinity focus position shown in Figure 2.

The diagrams are known to the expert representations.

The field curvature in FIG. 4 is shown in millimeters for the wavelengths 436 nm, 546 nm, and 656 nm for sagittal and tangential rays for the focus position from FIG. Here, it essentially depends on all the curves being in a range of -0.05 to +0.21 mm. The field curvature is in a range of not more than 0.26 mm in width for an image circle diameter of 43 mm, and approximately changes in direct proportion to the scale of the entire system (sensor-sized lens). In addition, the field curvature changes depending on the sensor diagonal according to the course of the curves in Figure 4.

In Fig. 5, the F-tan (theta) designation is shown in percent.

In Fig. 6, the spherical aberration is shown for the same wavelengths as in Fig. 4 in millimeters. Significantly, the longitudinal aberration for rays (e.g., for a pupil radius of 8.7 mm) is in the range of -0.06 to +0.2 mm.

The spherical aberration is in a range of not more than 0.26 mm in width for an image circle diameter of 43 mm, and approximately changes in direct proportion to the scale of the entire system (sensor-diagonal lens).

The corresponding diagrams for field curvature, distortion and spherical aberration for the focus position of the near field according to FIG. 3 are shown in FIGS. 7 to 9.

The field curvature in Fig. 7 is shown in millimeters for the wavelengths 436 nm, 546 nm, and 656 nm for sagittal and tangential rays. Here it essentially depends on all the curves being in a range of -0.03 to +0.30 mm. These values apply to an image circle diameter of 43 mm and change with other sensor diagonals. In Fig. 8, the F-tan (theta) designation is shown in percent.

In Fig. 9, the spherical aberration for the same wavelengths as in Fig. 7 is shown in millimeters. Significantly, the longitudinal aberration for rays (e.g., for a pupil radius of 8.7 mm) is in the range of -0.07 to +0.22 mm. These values apply to an image circle diameter of 43 mm and change with other sensor diagonals.

It can be clearly seen from the illustrations of FIGS. 4 to 9 that a very high imaging performance can be achieved for both focal positions.

Corresponding values are stored in the control unit 17 for the positions of the two optical groups 11, 12 for focus positions which lie between infinity and the near range. Having usually no analytical function for the positions of the optics groups 11, 12 in

Depending on the focus distance can be set up, for different focal distances values can be simulated as nodes and then by these values in a known manner, for example. a polynomial function are fitted, which is then stored for setting the corresponding position of the two optical groups 11, 12 in the control unit 17 and is used by this to control the actuators 15 and 16.

Since the objective 1 according to the invention has exactly four lenses 7-10, it can be provided with low weight and low costs, although the described high

Imaging services are available.

The lens 1 may be firmly connected to the camera body 2, so that replacement is not possible. However, it is also possible that the lens 1 is designed as a replaceable lens 1, which can be connected to the camera body 2 and released from it. For this purpose, known screw or bayonet connections can be used.

The objective 1 together with the mirrorless system camera 3 represents a camera according to the invention. The mirrorless system camera 3 can be further known to the person skilled in the art

Have features that are necessary for the operation of the system camera 3.

FIG. 10 shows a further exemplary embodiment of the objective 1 according to the invention, which has the same optical structure as the objective 1 described in connection with FIGS. The objective 1 according to FIG. 10 is focused at infinity and, unlike the previously described objective 1, has not two but six actuators 15, 16, 18, 19, 20 and 21. Each actuator 15, 16 and 18-21 can be one of the lenses 7-10 and a of the apertures 13, 14, so that each lens 7-10 and aperture 13, 14 can be displaced by itself and independently of the other lenses 7-10 and apertures 13, 14, respectively, along the optical axis OA For example, to adjust or change the focus position and / or the imaging performance of the lens 1.

Further, the lens may be an element of an optical system, wherein the system additionally comprises at least one accessory element such. Includes macrolenses, USB dock, lens hood, sun visor, extender, zoom adapter, teleconverter and autofocus unit. The autofocus unit may be incorporated into the lens or be part of a camera or function as an external element (e.g., HRLV-MaxSonar-EZ ultrasonic sensor). An extender may e.g. be designed in the form of an adapter for coupling the lens to different cameras with different camera mounts. Alternatively, the extender can be an adapter with an optical arrangement with additional optical elements, e.g. Lenses, mirrors (including dichroic), prisms, apertures, and diffractive optical elements. Furthermore, the invention relates to a use of the objective in at least one of the fields of industrial photography, cinematography, motor vehicles, automation, positioning of objects for machining, machine tools, aerospace,

Medical sensors and electrophotography.

FIG. 11 shows a further exemplary embodiment of the objective 1 according to the invention, which is mounted on the housing 2 of the mirrorless system camera 3. In addition, a front optics 22 is provided, which with the lens 1 on the side facing away from the image sensor 6

Lens 1 is coupled.

FIG. 12 shows a modification in which a relay optic 23 is arranged between the housing 2 and the objective 1.

FIG. 13 shows a modification in which both the front optics 22 and the relay optics 23 are provided. The objective 1 with the attachment optics 22 and / or the relay optics 23 forms / forms a modified objective 1 according to the invention. a telephoto and / or wide-angle lens are provided.

The objective according to the invention can have an adjustable de-click mechanism. When the de-clicking mechanism is set, stepless rotation and / or stepless axial movement of the aperture stop 13, the combo end 14 and / or at least one of the lenses 7-10 can be performed. It is thus a continuous movement without detents possible. When the de-clicking mechanism is turned off, a stepwise adjustment can again be made. The control unit 17 can be used in addition to the already described control of the actuators 15, 16 and 18 - 21 for communication and / or data exchange with a (not shown) control unit in the camera body 2 and / or an external device. The connection required for this can be a wireless connection or a cable-based connection. The external device may be a mobile phone, a portable computer, another computer, a tablet computer or a remote control.

The control unit 17 can generate metadata that can be used in post-processing the recordings. As metadata one can e.g. Distortion, Aperture, Distance, Randlichtabfall, transverse chromatic aberration, focal length, transmission and / or length transmitted. The metadata can be transferred in common data formats. For example, the data format for the XD interface from Carl Zeiss AG (for example the ZEISS CP.3

Object family). One can then speak of an XD-suitable interface.

FIG. 14 shows a further modification of the objective 1 according to the invention. In this case, the lens 1 has a temperature sensor 24 which is connected to the control unit 17. The data of the temperature sensor 24 can be used, for example, to perform image stabilization and / or focus correction.

Further, the lens 1 may include a focus sensor 25 which is connected to the control unit 17. In this case, every known focus sensor 25 is suitable in principle. It may be, for example, a laser-based distance sensor or a time-of-flight sensor.

Focusing can be done as follows. In a first step, the

Blur detected by an image sensor. This is followed by the detection of the distance by means of the focus sensor 25, which may be a laser-based distance sensor. Based on the measurement data of the sensor 25, the control unit 17 performs an adjustment of the lenses 7 - 10 and / or the diaphragms 13, 14 in such a way that a sharp image is achieved. These

Information about the positions of the optical elements is then provided by the

Control unit 17 to a control unit of the camera 3 transmitted.

The focusing can be done by means of one or two or three distance sensors 25. The distance sensors 25 can emit light in different wavelength ranges. As already mentioned, a time-of-flight sensor can also be installed in the objective 1 in order to measure the distance. Alternatively, the distance information by means of in the Control unit 17 implemented algorithms are determined. In particular, you can

Algorithms of artificial intelligence are emulated. The distance information can then be used to adjust the sharpness level.

Furthermore, the objective 1 according to the invention can detect an image stabilization unit. For this purpose, for example, a position sensor 26, which may be formed as a gyroscope sensor, may be provided. The position sensor 26 can determine a tilting of the objective 1 and then, for example, move the lens 9 along the y axis via the actuator 16 or, for example, via the actuator 21 according to FIG. 10 such that the desired image stabilization is achieved.

The method of performing image stabilization may thus include the following steps.

It detects a movement of the picture. Then, a movement of the optical system (for example, via the position sensor 26) is detected. It is a target position of the lenses 7 - 10 and the aperture 13, 14 determined. Then, an actual position of the lenses 7 - 10 and the aperture 13 and 14 is determined. From the comparison of the desired and actual position, the position of the lens 9 is then adjusted or adjusted via the actuator 16, 21 such that the actual position coincides with the desired position as far as possible. The steps of determining the setpoint and actual position, comparing the setpoint and actual position and setting the position to compensate for the actual position with the setpoint position are carried out until the desired image stabilization is achieved. Of course, it is also possible in principle to adjust or adjust the position of at least one element of the group of lenses 7 - 10 and diaphragms 13, 14 via the actuators 15, 16, 18 - 21 so that the actual position coincides with the desired value - Position matches as possible.

The objective 1 according to the invention can e.g. used as a lens on mobile phones, reversing cameras on vehicles, on-chip systems. The objective 1 according to the invention can also be designed as a macro objective, as shown schematically in FIG. 15. The objective 1 can be focused by β '= 0 to β' = -1, this being true in the case where the mapping for β '= 0 is from the infinite.

In FIGS. 16-18 diagrams for explaining the field curvature, the distortion and the spherical aberration of the objective 1 according to the invention according to FIG. 14 are shown in the same way as in FIGS.

The objective 1 according to the invention can have an adjusting ring for adjusting the coma end 14 in order to be able to achieve a flexibility of the image design. This can be a higher resolution or more light or a significant depth of field and still dark corners are achieved. This can then be used in the post-processing of the recording. For example, the user can choose between a high resolution and darker corners or brighter corners and less resolution for the corners. In addition, as a means of design, it can dim the objective 1 according to the invention by means of the aperture diaphragm 13, in order to achieve a high depth of focus and nevertheless set a high marginal light drop with the darkening of the coma end for dark corners.

In addition to the provision of corresponding adjustment rings for the diaphragm 13, 14, these can be additionally controlled or adjusted accordingly by means of the control unit 17.

Furthermore, the objective 1 can have further optical elements (or optically active elements). These optically active elements can be arranged in front of or behind the first or second optical group 11, 12. Specifically, it may be adjustable image correction elements, e.g. have a free-form surface, such as Alvarez plates, or finite systems, which may consist of several optical elements act.

The optically active elements can be adjusted based on respective control commands and the correction function. This may cause aberrations, such as spherical aberrations and / or differences in refractive indices are reduced / corrected. In a classical system with an Alvarez lens, translational movement of two complementary sub-lenses relative to each other is used. Alternatively, the sub-lenses may be adjusted so that focus adjustment is accomplished by rotating at least one of the lenses. Further, the focus adjustment can be achieved by rotating a mirror that affects the overlap of the two sub-lenses, which together form an effective lens with a refractive power that depends on the angle of rotation of the mirror.

There are thus provided adjustable image correction elements for a dynamic adjustment of the frequency (blur effect).

Claims

claims

Lens, especially for a mirrorless system camera, with

a first lens (7) with positive refractive power,

a second lens (8) with negative refractive power,

a third lens (9) with positive refractive power and

a fourth lens (10) with negative refractive power,

wherein the lenses (7-10) in the order mentioned starting from the object side along an optical axis (OA) of the lens (1) are arranged one behind the other, wherein the first and second lens (7, 8) has a first optical group (11) positive refractive power and the third and fourth lenses (9, 10) form a second optical group (12) with positive refractive power,

wherein between the second and third lens (8, 9) a first diaphragm (13) is arranged and

the optical groups (11, 12) independently of one another, at least one of the lenses (7-10) independent of the other lenses (7-10) and / or the first diaphragm (13) independently of the other lenses (7-10) along the optical axis (OA) is displaceable / to change the focus position and / or the imaging performance.

Lens according to claim 1, wherein

the displaceability of at least two elements of a group of lenses, which comprises the lenses (7-10), the optical groups (11, 12) and the first diaphragm (13), is predetermined such that they always differ in the same direction only

Routes are displaced.

Lens according to claim 2, wherein

the displaceability of the two optical groups (1 1, 12) is predetermined so that the distance by which the first optical group (11) is shifted to change from a first to a second focus position, is greater than the distance to which the second optical group (12) is shifted to change from the first to the second focus position.

4. Lens according to one of the above claims, wherein at least one of the boundary surfaces of the lenses (7, 8) of the first optical group (1 1) and / or at least one of the boundary surfaces of the lenses (9, 10) of the second optical group (12) is aspherically curved in each case.

An objective according to any one of the preceding claims, wherein the first and second lenses (7, 8) are spaced apart from each other by an unalterable distance, and third and fourth lenses (9, 10) are spaced apart from each other by a non-changeable distance.

6. Lens according to one of the above claims, wherein the first diaphragm (13) is part of the second optical group (12) and with this along the optical axis (OA) is displaceable.

7. Lens according to one of the above claims, in which a second diaphragm (14) is arranged and which is changeable in its diameter and / or which is displaceable along the optical axis (OA).

8. Lens according to one of the above claims, wherein the diameter of the first panel (13) is changeable.

9. Lens according to one of claims 1 to 7, wherein the diameter of the first diaphragm (13) is not changeable and thus has a fixed value.

10. Lens according to one of the above claims, wherein the lens (1) formed with a fixed focal length and the focal length is selected so that in one of the system camera (3) having an image sensor (6), mounted state of the lens (1 ) the ratio of the focal distance, which is the distance of the image sensor (6) facing interface (G8) of the fourth lens (10) to the image sensor (6) of the system camera (3) following

Inequality fulfilled:

0.2 <focal length / focal length <0.55.

11. Lens according to one of the above claims, wherein the objective (1) is designed so that the half diagonal image angle (w) satisfies the following inequality:

20 ° <w <30 °.

12. Lens according to one of the above claims, wherein the lens (1) is designed so that the F-number satisfies the following inequality: 2.0 <F-number <4.0.

The lens according to any one of the above claims, wherein the lens (1) is designed so that both the field curvature and the spherical aberration are in a range of not more than 0.26 mm in width for an image circle diameter of 43 mm each change in direct proportion to the scaling of the overall system.

14. Lens according to one of the above claims, wherein

for each element of a group of lenses to be moved, comprising the lenses (7-10), the optical groups (11, 12) and the first and second diaphragms (13), an actuator (15,

16) is provided for moving the corresponding element of the lens group, wherein the control unit (17) or the actuators (15, 16) for changing the

Focus position and / or imaging performance.

15. Camera with

a lens (1) according to any one of the above claims and an image sensor (6).

16. A camera according to claim 15, wherein

no fold-away mirror is arranged between the lens (1) and the image sensor (6).

17. Optical system with

a lens (1) according to any one of claims 1-14 and at least one of

Accessories from the following group:

a. macro lens

b. USB dock

c. Aperture especially lens hood and sun visor,

d. Extender

e. Zoom adapter

f. teleconverter

G. Autofocus unit

18. Use of the lens according to one of claims 1 -14 on at least one of the following areas:

a. Industrial photography

b. cinematography

c. motor vehicles

d. Automation, in particular positioning,

e. machine tools

f. Aerospace G. Medical sensors h. electrophotography