MICROSCOPE WITH OVERSIZED ZOOM SYSTEM

Abstract

The invention relates to a microscope (10) that encompasses an objective system (30) having at least two objectives (44, 52) selectably introducible into the beam path of the microscope (10), and a zoom system (32). The zoom system (32) has a total zoom range (90) within which the focal length of the zoom system (32) is settable. A zoom sub-range (96, 98) within the total zoom range (90) is allocated to each of the objectives (44, 52).

Claims

1. A microscope (10), comprising: an objective system (30) that has at least two objectives (44, 52) having different respective focal lengths, wherein a selected one of the at least two objectives (44, 52) is introducible into a beam path of the microscope; and a zoom system (32) that has a total zoom range (90), a respective total magnification of an object to be examined microscopically resulting respectively from the focal length of the selected objective (44, 52) and from a magnification of the zoom system (32) set within the total zoom range (90), wherein a first zoom sub-range (96) within the total zoom range (90) is allocated to a first objective of the at least two objectives (44, 52) and a second zoom sub-range (98) is allocated to a second objective of the at least two objectives (44, 52), wherein at least one of the first and second zoom sub-ranges (96, 98) is narrower than the total zoom range (90), and wherein the microscope further comprises limiting means (46, 48, 54, 56) for limiting adjustability of the zoom system (32) to the zoom sub-range that is allocated to the selected objective (44, 52).

2. The microscope (10) according to claim 1, wherein each of the first and second zoom sub-ranges (96, 98) is narrower than the total zoom range (90), and the first zoom sub-range is different from the second zoom sub-range.

3. The microscope (10) according to claim 1, wherein a respective zoom sub-range is allocated to each of the at least two objectives (44, 52).

4. The microscope (10) according to claim 3, wherein the zoom sub-ranges (96, 98) of all the objectives (44, 52) are respectively narrower than the total zoom range (90).

5. The microscope (10) according to claim 2, wherein the first and second zoom sub-ranges (96, 98) at least partly overlap one another.

6. The microscope (10) according to claim 2, wherein the first zoom sub-range (96) has a zoom factor defined by a lower limit and an upper limit of the first zoom sub-range (96), the second zoom sub-range (98) has a zoom factor defined by a lower limit and an upper limit of the second zoom sub-range (98), and the zoom factor of the first zoom sub-range (96) is equal to the zoom factor of the second zoom sub-range (98).

7. The microscope (10) according to claim 2, wherein a lower limit of the first zoom sub-range (96) corresponds to a lower limit (92) of the total zoom range (90), and an upper limit of the second zoom sub-range (98) corresponds to an upper limit (94) of the total zoom range (90).

8. The microscope (10) according to claim 2, wherein the focal length of the first objective (44) is longer than the focal length of the second objective (52), wherein the first and second zoom sub-ranges (96, 98) are preset such that the first zoom sub-range (96) encompasses magnifications that are lower than a lowest magnification of the second zoom sub-range (98).

9. The microscope (10) according to claim 2, wherein the focal length of the second objective (52) is shorter than the focal length of the first objective (44), wherein the first and second zoom sub-ranges (96, 98) are preset such that the second zoom sub-range (98) encompasses magnifications that are higher than highest magnification of the first zoom sub-range (96).

10. The microscope (10) according to claim 1, wherein the focal length of the second objective (52) is shorter than the focal length of the first objective (44); a lower limit of the first zoom sub-range allocated to the first objective (44) corresponds to a lower limit of the total zoom range; and an upper limit of the second zoom sub-range allocated to the second objective (52) corresponds to an upper limit of the total zoom range.

11. The microscope (10) according to claim 1, wherein the at least two objectives are embodied parfocally.

12. The microscope (10) according to claim 1, wherein at least one stop (46, 48, 54, 56) is provided as the limiting means on each of the first and second objectives (44, 52); and the adjustability of the zoom system (32) is limited by the at least one stop (46, 48, 54, 56) to the respective zoom sub-range (96, 98) of the selected objective (44, 52).

13. The microscope (10) according to claim 1, further comprising an electric drive unit for adjusting the zoom system (32), and a control unit for applying control to the drive unit; wherein the first and second zoom sub-ranges (96, 98) are stored in the control unit; and the control unit applies control to the drive unit such that an adjustment is possible in each case only within the respective zoom sub-range (96, 98) of the selected objective (44, 52).

14. The microscope (10) according to claim 1, further comprising a diaphragm for setting a light transmittance as a function of the selected objective (44, 52) and/or of the set magnification of the zoom system (32).

15. The microscope (10) according to claim 1, wherein the zoom system (32) comprises at least two lens groups (34 to 38), at least one of the at least two lens groups being movable along an optical axis (50) in order to set the magnification of the zoom system (32).

16. The microscope (10) according to claim 1, wherein the microscope (10) is a digital microscope that comprises an image capture unit (40) on which an image of the object to be examined microscopically is imageable with the aid of the zoom system (32).

Description

BRIEF DESCRIPTION OF THE DRAWING VIEWS

[0033] Further features and advantages of the invention are evident from the description below, which explains the invention in more detail with reference to exemplifying embodiments in conjunction with the attached Figures, in which:

[0034] FIG. 1 is a schematic perspective depiction of a digital microscope;

[0035] FIG. 2 schematically depicts a magnification system of the microscope according to FIG. 1;

[0036] FIG. 3 schematically depicts a magnification system according to FIG. 2 when a first objective is in use;

[0037] FIG. 4 schematically depicts a magnification system according to FIG. 2 when a second objective is in use;

[0038] FIG. 5 schematically depicts a total zoom range and the zoom sub-ranges of the first and the second objective;

[0039] FIG. 6 is a schematic perspective depiction of a portion of the microscope according to FIG. 1;

[0040] FIG. 7 is a further schematic perspective depiction of the portion according to FIG. 6;

[0041] FIG. 8 schematically depicts a housing of the microscope;

[0042] FIG. 9 is a further schematic perspective depiction of the housing according to FIG. 8;

[0043] FIG. 10 schematically depicts a detail of the microscope;

[0044] FIG. 11 schematically depicts a portion of an objective and of an objective housing;

[0045] FIG. 12 is a schematic perspective depiction of the actuation element of the zoom system in a first rotational position;

[0046] FIG. 13 is a schematic perspective depiction of the actuation element according to FIG. 12 in a second rotational position;

[0047] FIG. 14 schematically depicts the actuation element with a first objective inserted, in a first operating state;

[0048] FIG. 15 schematically depicts the actuation element with a first objective inserted, in a second operating state;

[0049] FIG. 16 schematically depicts the actuation element with a second objective inserted, in a third operating state;

[0050] FIG. 17 schematically depicts the actuation element with a second objective inserted, in a fourth operating state;

[0051] FIG. 18 schematically depicts the actuation element with a third objective inserted, in a fifth operating state; and

[0052] FIG. 19 schematically depicts the actuation element with a third objective inserted, in a sixth operating state.

DETAILED DESCRIPTION OF THE INVENTION

[0053] FIG. 1 is a schematic perspective depiction of a digital microscope. Microscope 10 encompasses a stationary stand body 12 as well as a pivoting unit 14 pivotable relative thereto.

[0054] Pivoting unit 14 encompasses at least one image capture unit with which an image of the objects to be examined microscopically can be acquired. In particular, by way of this image capture unit not only individual images but also videos can be acquired, making it possible to observe the object to be examined microscopically from different angles of view.

[0055] The pivoting unit furthermore comprises an objective and a zoom system with which different magnifications of the objects to be examined microscopically can be set. The objective system has a plurality of objectives, one of which is introduced respectively into the beam path.

[0056] The image capture unit, the objective system, and the zoom system are not visible in FIG. 1, since they are concealed by housing 16 of pivoting unit 14.

[0057] The construction of the objective system and of the zoom system will be described in further detail below in conjunction with FIGS. 2 and 4.

[0058] The objectives of the objective system are embodied, in particular, parfocally, so that no refocusing needs to be performed by the operator upon an objective change. The objectives are matched in particular to the distance between the rotation axis, around which pivoting unit 14 can be rotated, and the interface of the objectives, thus yielding a eucentric system the consequence of which is that refocusing does not need to occur upon pivoting of pivoting unit 14.

[0059] Also arranged on the stand body is a specimen stage 18 on which the objects to be examined microscopically are mounted. This specimen stage 18 can be adjusted, with the aid of positioning wheels 20, relative to stand body 12 in the direction of double arrow P1, thus allowing focusing of the objects to be examined microscopically.

[0060] FIG. 2 shows, entirely schematically, the magnification system arranged in pivoting unit 14 in three different settings. The magnification system encompasses an objective system 30 as well as a zoom system 32, the interaction of which causes the desired total magnification to be achieved. Objective system 30 encompasses at least two objectives 44, 52 having different focal lengths, one of which is respectively pivoted selectably into the beam path of microscope 10.

[0061] Zoom system 32 comprises three lens groups 34 to 38, two lens groups 36, 38 of which are adjustable in the direction of optical axis 50. In an alternative embodiment of the invention the zoom system can also encompass only two lens groups 34 to 38, only one lens group 34 to 38 of which is axially adjustable. Zoom systems having more than three lens groups 34 to 38 are also conceivable.

[0062] In the embodiment shown in FIG. 2, the image of the object is imaged via zoom system 32 directly onto an image capture unit 40 that can be, in particular, a camera.

[0063] FIG. 2 shows three settings of zoom system 32. In the left setting, zoom system 32 is set so that it has a maximum focal length and thus produces a maximum magnification. Field angle 42, which indicates the angle of the main beam with respect to optical axis 50 in the region of the interface to objective system 30, is correspondingly minimal.

[0064] The right setting depicted in FIG. 2, conversely, shows the other extreme setting of zoom system 32, namely the setting in which zoom system 32 has a minimum focal length and correspondingly produces a minimum magnification effect. In this case field angle 42 is maximal.

[0065] The middle case shown in FIG. 2 represents an intermediate position in which zoom system 32 achieves a focal length that is longer than the minimum focal length and shorter than the maximum focal length. Field angle 42 is correspondingly between field angles 42 of the other two cases.

[0066] The respective total magnification of microscope 10 results from the quotient of the focal length set for zoom system 32, and the focal length of that objective 44, 52 of objective system 30 which is introduced into the beam path.

[0067] Zoom system 32 has a total zoom range that indicates which focal lengths of zoom system 32 can be set via zoom system 32. This total zoom range is depicted in FIG. 5, by way of example, by arrow 90; lower limit 92 indicates the minimum focal length of zoom system 32 that is produced for the setting shown on the right in FIG. 2. Upper limit 94 of total zoom range 90 correspondingly indicates the maximum focal length of zoom system 32 which is produced for the setting shown on the left in FIG. 2. Total zoom range 90 is thus predefined, in particular, in physically constrained fashion, and indicates the maximum possible range of magnifications of zoom system 32.

[0068] As already described, objective system 32 encompasses several objectives 44, 52 having different focal lengths. A zoom sub-range within total zoom range 90 is allocated to each of these objectives 44, 52, a first zoom sub-range 96 for a first objective 44 and a second zoom sub-range 98 of a second objective 52 being depicted in FIG. 5. The two zoom sub-ranges 96, 98 each cover only a portion of total zoom range 90, and in particular are configured in such a way that they at least partly overlap.

[0069] Microscope 10 is embodied in such a way that zoom system 32 is always adjustable only within the respective zoom sub-range 96, 98 that is allocated to objective 44, 52 currently pivoted into the beam path.

[0070] In the exemplifying embodiment depicted in FIG. 5, first objective 44 to which zoom sub-range 96 is allocated has a longer focal length compared with second objective 52, and thus a lesser magnification effect. First zoom sub-range 96 is correspondingly also selected in such a way that it covers the lower magnifications of total zoom range 90 as compared with second zoom sub-range 98, whereas second zoom sub-range 98 encompasses the higher magnifications of total zoom range 90.

[0071] The result thereby achieved is that for objectives 52 having a high magnification, i.e. a short focal length, high magnifications are also achieved by the zoom system, so that a high total magnification is achieved overall.

[0072] Conversely, with objectives 44 of low magnification, i.e. having a wide field angle, zoom sub-range 96, for which range zoom system 32 again has low magnification and thus a wide field angle, is allocated.

[0073] The sub-range of zoom system 32 which is used is thus always matched to the properties of the respective objective 44, 52.

[0074] FIG. 3 schematically depicts the magnification system of FIG. 2 in two states, first objective 44 of objective system 30 being introduced into the beam path. With first objective 44, which has a relatively long focal length, i.e. low magnification, the adjustability of zoom system 32 is limited by limiting elements 46, 48 in such a way that, compared with the maximum adjustment range shown in FIG. 2, adjustment is possible down to the minimum focal length (FIG. 3, right) but not up to the maximum focal length. An adjustment of zoom system 32 is correspondingly possible only within first zoom sub-range 96. The movement of lens groups 36, 38 toward one another is limited, via limiting elements 46, 48, to the state shown on the left in FIG. 3. Limiting elements 46, 48 are, in particular, stops that are coupled to first objective 44, so that upon introduction of first objective 44 into the beam path, stops 46, 48 are also automatically moved so that they are arranged in such a way that they are arranged in the movement region of lens groups 34 to 38.

[0075] FIG. 4 shows the case in which second objective 52 is pivoted into the beam path. This objective 52 as well in turn encompasses stops 54, 56 with which the adjustment of zoom system 32 can be limited to second zoom sub-range 98. With this second objective 52, stops 54, 56 prevent lens groups 36, 38 from being moved farther apart from one another than the state shown on the right in FIG. 4, so that setting of the minimum magnification is prevented.

[0076] Limiting elements 46, 48, 54, 56 are depicted merely schematically in FIGS. 3 and 4. In the concrete embodiment as shown in FIGS. 6 to 19, limiting elements 46, 48, 54, 56 are arranged in particular not in zoom system 32 but instead, as will be explained below in detail, as adjustable pins 130 to 136 at the interface between objective system 30 and zoom system 32.

[0077] As depicted in FIG. 5, zoom sub-ranges 96, 98 in which zoom system 32 is respectively operated are thus configured to be narrower than the maximum zoom range 90, and for that reason zoom system 32 is also referred to as overdimensioned or oversized.

[0078] Compared with known microscopes in which the entire zoom range is always used, and the maximum and minimum magnification is brought about by corresponding selection of the objectives, the objectives that are used now no longer need to have such different focal lengths for the same total magnification range, as the following quantitative example is intended to illustrate:

[0079] In order to achieve a magnification range of between 0.15 and 30 with two objectives in a microscope according to the existing art, for example, a first objective having a focal length of 20 and a second objective having a focal length of 250 are used. The zoom system has an adjustable focal length of between 38 and 600. The maximum magnification of 30 is achieved by using the first objective and setting the maximum focal length of the zoom system. In this case a magnification of 30 is obtained using the calculation formula b=f zoom/f objective, therefore 600/20=30.

[0080] The minimum magnification of 0.15 is correspondingly obtained using the second objective and the minimum focal length of the zoom system, as the quotient of 38 and 250.

[0081] In order to achieve the same magnification range of 0.15 to 30 with the microscope according to the embodiment of the invention, a zoom system 32 having an adjustable focal length of between 21 and 600 is now used. The zoom sub-range of first objective 44 is 38 to 600; the zoom sub-range of the second objective is 21 to 336. First objective 44 has a focal length of 140; second objective 52 has a focal length of 20.

[0082] For a maximum magnification of 30, once again second objective 52 is used together with the maximum focal length of zoom system 32. For a minimum magnification, first objective 44 is used together with the minimum focal length of zoom system 32, once again yielding the factor 0.15 as the quotient of 21 and 140.

[0083] The same total magnification range can thus be achieved, but the resulting focal length difference between objectives 44, 52 that are used is considerably smaller.

[0084] This has the advantage that objectives 44, 52 can be substantially more compact and of simple construction. In particular, a parfocal objective system 30 can be realized by way of the smaller spread between the focal lengths of objectives 44, 52. A further result is that the zoom factor selectable by the operator is the same for each objective 44, 52, i.e. in the aforementioned example a zoom factor of 16 (336/21 and 600/38).

[0085] The allocation of zoom sub-ranges to different objectives can be used not only with digital microscopes but also, alternatively, with any other microscopes having an objective system and a zoom system.

[0086] FIGS. 6 and 7 are respective schematic perspective depictions of a detail of microscope 10 of FIG. 1, depicting a portion of zoom system 32 and of objective system 30. The emphasis with respect to the depiction in FIGS. 6 and 7 and also the subsequent Figures is on explaining how the limitation of the adjustability of zoom system 32 to the respective zoom sub-ranges 96, 98 of the various objectives 44, 52 is accomplished entirely mechanically.

[0087] Objective system 30 comprises a housing 100 in which is provided a receiving region 102 in which the respective objective 44 currently introduced into the beam path is received. In the depiction of FIG. 7, no objective is received in this receiving region 102. In the depiction of FIG. 6, conversely, an objective 44 is slid into receiving region 102. Objective 44 is mounted here on a plate 104 and surrounded by a housing 106, and plate 104 can be fastened onto housing 100 of objective system 30.

[0088] Objective system 32 comprises a rotary wheel 108 that can be rotated by the operator of microscope 10. For better handling, knurling 110 is provided in particular on the peripheral surface of rotary wheel 108. Rotary wheel 108 has, on the side facing away from knurling 110, a tooth set 112 by way of which rotary wheel 108 is in engagement, with the aid of a gear system 114, with a spindle 116. Spindle 116 is correspondingly rotated by rotating rotary wheel 108.

[0089] Lens groups 36, 38 are mounted via holders 118, 120 on spindle 116. Lens groups 36, 38 are correspondingly moved toward or away from one another upon rotation of spindle 116.

[0090] FIGS. 8 and 9 are respective schematic perspective depictions of housing 100 of objective system 30. A total of four pins 130 to 136 are arranged in housing 100, movably, in particular vertically, in the direction of double arrow P2. Pins 130 to 136 are movable between an activated or deactivated position; in the depiction of FIG. 8, pins 130, 134 are shown in the activated position and pins 132, 136 in the deactivated position. In the activated position, pins 130 to 136 project a predetermined distance out from surface 138 of housing 100 toward rotary wheel 108. In the deactivated position, pins 130 to 136 are arranged within housing 100 and, in particular, do not project out of it. Alternatively, they can also project slightly out of housing 100 in the deactivated position, but not as far as in the activated position.

[0091] As shown in FIG. 10, pins 130 to 136 are each preloaded in the activated position via a spring 140.

[0092] Each of pins 130 to 136 is furthermore connected to a respective pin 142 to 148. As shown in FIG. 9, these pins 142 to 146 project into receiving region 102 and are each guided in an elongated hole of housing 100.

[0093] A movement of pins 142 to 148 allows pins 130 to 136 to be moved, against the return force of spring 140, from the activated into the deactivated position. Pins 142 to 148 must be moved for this purpose downward in the direction of arrow P3. In the depiction of FIG. 9, pins 144, 148 are moved downward against the return force of the respective spring so that, as shown in FIG. 8, the associated pins 132, 136 are correspondingly arranged in the deactivated position.

[0094] Pins 142, 148 are moved, with the aid of the respective objective 44 introduced into receiving region 102, by contact with the corresponding objective housing 106. FIG. 11 schematically depicts a portion of first objective 44. Two contact elements 150, 152 are provided on housing 106 of objective 44 on opposite sides of housing 102. The two contact elements 150, 152 each have a stepped contact surface 154. When objective 44 is slid into receiving region 102, pins 142 to 148 are then moved downward as shown in FIG. 10, provided the respective contact element 150, 152 comprises, in the region of the respective pin 142 to 148, a corresponding step on contact surface 154 which moves the corresponding pin 142 to 148 downward and holds it in that position. Pins 130 to 136 are correspondingly adjusted between the activated and deactivated position via pins 142 to 148.

[0095] Contact elements 150, 152 are configured differently depending on the objective 44, so that other pins 130 to 136 are arranged respectively in the activated or deactivated position.

[0096] FIGS. 12 and 13 are respective perspective depictions of zoom system 32 depicting different rotational positions.

[0097] A gated disk 160 is arranged nonrotatably on rotary wheel 108 on the side facing toward objective system 30 and thus toward housing 100 of objective system 30. Two gates 162, 164 in the shape of circular segments, into which pins 130 to 136 can engage if they are respectively arranged in the activated position, are provided in this gated disk 160. Gated disk 160 furthermore comprises a protrusion 166 with which the rotatability of rotary wheel 108 is limited to a maximum rotation range. For that purpose, two stops 172, 174 are provided on a nonrotatable housing part 170 that is not rotated together with rotary wheel 108.

[0098] In the rotational position shown in FIG. 12, projection 166 abuts against first stop 172 so that the handwheel can be rotated only in the direction of arrow P4. This position is referred to in particular as the 0 rotational position.

[0099] In FIG. 13, conversely, projection 166 abuts against second stop 174 so that the handwheel can be rotated only in the direction of arrow P5, that rotation direction P5 being opposite to rotation direction P4. In this second state, rotary wheel 108 is maximally rotated with respect to the 0 position shown in FIG. 12. This corresponds in particular to a rotation through an angle of 130. The maximum rotation range of the handwheel is thus 130. The total zoom range is predefined by this maximum rotation range.

[0100] Because of the arrangement of pins 130 to 136 in the activated position, and the engagement thereby produced into one of the two gates 162, 164, the rotatability of rotary wheel 108 can be limited depending on the objective 44 used, so that depending on the objective 44, handwheel 108 can be rotated only in a rotation sub-range that represents a sub-range of the maximum rotation range. The zoom sub-range is thus correspondingly set via these rotation sub-ranges, since a limitation of the rotation range of the handwheel automatically signifies a limitation of the available zoom range.

[0101] FIGS. 14 to 19 depict by way of example, for an objective system 30 having three different objectives, the manner in which a different rotation sub-range of rotary wheel 108 is defined for each of the three objectives by way of the different arrangement of pins 130, 132 in the respectively activated or deactivated position due to the differing configuration of contact elements 150, 152 of the various objectives, and thus a different zoom sub-range is allocated to the respective objective.

[0102] FIGS. 14 to 15 depict the situation that results when a first objective is introduced into receiving region 102, such that with this first objective, pin 132 is arranged in the activated position and pins 130 to 136 in the deactivated position. As shown in FIGS. 14 and 15, pin 132 thus engages into gate 162. Handwheel 108 can be rotated here between the 0 rotation position shown in FIG. 14 and the 112 rotation position shown in FIG. 15. A rotation beyond 112 is not possible, since pin 132 strikes against the end region of gate 162.

[0103] Alternatively, the other pins 130, 134, 136 could also be arranged in the activated position. In this case pins 134, 136 would firstly rest on the surface of gated disk 160 and would then, upon a slight rotation out of the 0 position, snap into gate 164. A movement back into the initial position would then not be possible.

[0104] FIGS. 16 and 17 depict the situation that results when a second objective is introduced into receiving region 102 instead of the first objective; with this second objective, pins 130, 136 are arranged in the activated position and pins 132, 134 in the deactivated position. By way of the engagement of pin 136 into gate 164, the rotatability of rotary wheel 108 with the second objective is limited to a minimum rotation angle of 9. Further rotation in direction P5, toward the 0 rotation position, is not possible.

[0105] Rotation in the opposite direction P4 is limited to a rotation angle of 121 by the engagement into gate 164 of pin 130, arranged in the activated position.

[0106] FIGS. 18 and 19 show the situation that results when a third objective is inserted into receiving region 102. With this third objective, contact elements 150 and 152 are embodied in such a way that pin 134 is arranged in the activated position and pins 130, 132, 134 are arranged in the deactivated position. Thanks to the engagement of pin 134 into gate 164, the rotatability of rotary wheel 108 in direction P5 is limited to 18 as a minimum rotation angle. In direction P4, conversely, rotary wheel 108 can be rotated until projection 166 strikes against second stop 174, i.e. to the maximum rotation angle of 130.

[0107] As a result of the above-described arrangement with pins 130 to 136 that engage into the corresponding gates 162, 164, it is thus possible to limit the rotatability of rotary wheel 108 in simple fashion, entirely mechanically, depending on the objective 44, so that a zoom sub-range within the total zoom range can be allocated in simple and reliable fashion to each objective 44.

[0108] In an alternative embodiment, more or fewer than four pins 130 to 136 can also be provided. Alternatively, more or fewer than two gates 162, 164 can also be provided. The number of pins and gates can be adapted in particular to the number of different objectives used, and thus to the number of different zoom sub-ranges required.

PARTS LIST

[0109] 10 Microscope [0110] 12 Stand body [0111] 14 Pivoting unit [0112] 16 Housing [0113] 18 Specimen stage [0114] 20 Positioning wheel [0115] 30 Objective system [0116] 32 Zoom system [0117] 34, 36, 38 Lens group [0118] 40 Image capture unit [0119] 42 Field angle [0120] 44, 52 Objective [0121] 46, 48, 54, 56 Limiting element [0122] 50 Optical axis [0123] 90 Total zoom range [0124] 92 Lower limit [0125] 94 Upper limit [0126] 96, 98 Zoom sub-range [0127] 100 Housing [0128] 102 Receiving region [0129] 104 Plate [0130] 106 Objective housing [0131] 108 Rotary wheel [0132] 110 Knurling [0133] 112 Tooth set [0134] 114 Gear arrangement [0135] 116 Spindle [0136] 118, 120 Holding element [0137] 130 to 136 Pin [0138] 138 Surface [0139] 140 Spring [0140] 142, 148 Pin [0141] 150, 152 Contact element [0142] 154 Contact surface [0143] 160 Gated disk [0144] 162, 164 Gate [0145] 166 Projection [0146] 170 Housing part [0147] 172, 174 Stop [0148] P1 to P5 Direction