US20010024570A1

US20010024570A1 - Optical auxiliary system for a camera

Info

Publication number: US20010024570A1
Application number: US09/739,430
Authority: US
Inventors: Wolfgang Weigel; Wolfgang Roessel
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-06-17
Filing date: 2000-12-18
Publication date: 2001-09-27
Also published as: EP1088251B1; BR9911352A; AU5406499A; DE59901075D1; WO1999066362A1; US6212334B1; EP1088251A1; DE19927577A1; CA2336197A1; DE19927730A1; CA2270451A1

Abstract

What is described here is an optical auxiliary system for a camera, which is arranged between a recording lens and a camera body and which comprises a relay system for projecting the image of the recording lens onto the film or the video pick-up.

The invention is characterised by the provision that the relay system is so structured that it produces more than one image and that the lens disposed directly on the camera body is a zoom lens.

Description

This is a continuation of pending International Applcation PCT/DE99/01785 filed Jun. 17, 1999, which designates the United States.[0001]

DESCRIPTION

1. Field of the Invention

The present invention relates to an optical auxiliary system for a camera in accordance with the introductory clause of

Patent claim

1.

The camera may be a photographic device, a film camera, particularly for professional applications, or a video camera.

2. Prior Art

An optical auxiliary system, which was taken as the basis when the introductory clause was worded, is known from the European Patent EP-A-0 690 327. Other auxiliary systems of the claimed general type are known from the U.S. Pat. Nos. 5,469,236 or 4,867,549. For an explanation of all the features which are not described here in details explicit reference is made to these prior art references.

All the known optical auxiliary systems have the feature in common that the normal recording lens, which is “directly on the camera body in all other cases”, is attached to the auxiliary system so that—depending on the configuration of the auxiliary system—it will be spaced from the camera body by a more or less wide distance. As a result, the operation is rendered more difficult for the operator, particularly when the recording lens is a zoom lens, because the operator must handle the lens for adjusting the focal length and actuate various elements for operating the camera, both over a comparatively long distance.

The known systems involve the further disadvantage that they cannot be adapted to different tasks in a simple manner. For instance, it is not possible to use one and the same system as a “straight” system and after simple retrofitting as a “bent” system.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is based on the problem of improving an optical auxiliary system for a camera in accordance with the introductory clause of

Patent claim

1 in such a way that handling will be facilitated and that the system can be retrofitted for different applications in a simple manner.

One inventive solution to this problem is defined in

Patent claim

1. Improvements of the invention are the subject matters of claims 2 et seq.

In accordance with the invention the relay system is so structured that it produces more than one image and that the lens disposed on the camera body directly is a zoom lens.

As a result it is not only possible to realise focusing and a possible rotation of the image “close to the camera” but also to select the section or window of the image. In particular, the zoom lens may be a varifocal lens, i.e. a lens in which focussing is not varied when the focal length is changed.

On account of this configuration it is moreover possible to retrofit the optical auxiliary system in a comparatively simple manner. It is possible, in particular, to select the object distance between the image of the recording lens and the first image at a distance so wide that it is possible to insert further systems such as path-folding units into this range.

It is particularly preferable that the path-folding unit is disposed between the recording lens and the relay system because in such a case the optical system, which is arranged in the recording path ahead of the path-folding unit is comparatively small and hence of light weight.

In another embodiment the path-folding unit comprises two elements whereof at least one deflects the light path by 90°. With this embodiment in particular an “offset” of the optical axis is possible which is suitable to solve also complex recording situations such as those occurring in macro pictures by means of the inventive auxiliary system. It is furthermore possible to achieve an amplification of the depth of focus.

In particular, the aforementioned one element may be a front-surface reflector whilst the other element is a path-folding element with image inversion so that a non-reversed image is obtained in an intermediate frame.

The aforedescribed configuration does not only permit an offset of the optical axis but also the pivoting of the offset optical axis. To this end an element is pivotable together with the recording lens in such a way that the respective pivoting angle of the recording lens corresponds to twice the pivoting angle of the pivotable element. The pivotable element may be the front-surface reflector in particular in this configuration.

In a preferred embodiment the relay system comprises three lenses and the zoom lens, with a prism for image rotation being disposed between the first and the second lens in particular. The two lenses which are arranged between the prism for image rotation and the zoom lens present preferably the same design and are disposed in symmetry relative to the centre plane therebetween.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will be described in the following by exemplary embodiments, without any restriction of the general inventive idea, with reference to the drawing to which explicit reference is made, by the way, with respect to the disclosure of all the inventive details which are not disclosed more exhaustively in the text. In the drawing: [0019]
FIG. 1 shows the fundamental structure of a first embodiment; [0020]
FIG. 2 is a view of a second embodiment which involves a modification of the embodiment according to FIG. 1, including an offset of the optical axis of the recording lens and the relay system; [0021]
FIG. 3 illustrates the structure of a roof prism employed in the invention; [0022]
FIGS. 4 and 5 are illustrations explaining the increase of the depth of focus in a modification of the second embodiment, and [0023]
FIG. 6 shows an embodiment of the gearing employed for a compensation of the image position. [0024]

DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a first embodiment of the invention wherein the relay system is so structured that it provides more than one intermediate image. [0025]
To this end, optical relay means [0026] 3, 4 and 6 as well as an optical zoom means 7 are arranged between an optical recording system 1 and an image plane 8 in which a film or a video pick-up may be provided. The optical recording system 1 creates an image in a first intermediate image plane 2. This image is projected into the second intermediate image plane 5 by the first relay system, which consists of the optical relay means 3 and 4 that constitute a tandem system.
The image created in the [0027] image plane 5 is projected into the film or video pick-up plane 8, respectively, by the second relay system, which consists of the optical relay means 6 with invariable focal length and the zoom lens 7. The zoom lens permits here an adjustment of the image section without the operator being bound to operate a recording lens, which is far remote due to the relay system.
The zoom lens [0028] 7 may be configured particularly in such a way that the image is enlarged or reduced in dependence on the focal length of the zoom lens 7.
FIG. 2 shows a second embodiment wherein elements identical with those of FIG. 1 are identified by the same reference numerals so that a repeated discussion thereof may be dispensed with. [0029]
In this embodiment elements are provided between the first [0030] intermediate image plane 2 and the first relay system, which consists of the optical relay means 3 and 4, which elements offset an optical axis 9 of the optical recording system 1 from a common optical axis 10 shared by the optical means 3, 4, 6 and 7.
The elements deflecting the path of rays are a front-[0031] surface reflector 11 and a roof prism 13 with image inversion. One embodiment of the roof prism 13 is illustrated in FIG. 3 which is referred to explicitly for an explanation of all the details.
In the embodiment shown in FIG. 2 it is possible to pivot the [0032] lens 1 about an axis 12 orthogonal on the drawing plane. To this end, the front-surface reflector 11 is rotatable about the axis 12. The optical recording system 1 is here pivotable together with the front-surface reflector 11 in such a way that the respective pivoting angle of the optical recording system 1 is twice the angle of rotation of the front-surface reflector 11 about the axis 12.
It is furthermore possible - in a manner known per se—to pivot the [0033] lens 1 about the section of the optical axis between the elements 11 and 13. It is also possible to perform a rotation about the optical axis 10, equally in a manner known per se.
When the [0034] lens 1 is pivoted about the section of the optical axis between the elements 11 and 13 the image on the image plane 8 would rotate without compensation. Therefore a prism 14 for image rotation is arranged between the optical relay means 3 and 4. The function of this prism will be explained in more details in the following with reference to FIG. 6.
The front-[0035] surface reflector 11 may be used not only for performing a pivoting motion of the recording lens 1 but also for the purpose of sharply projecting an object plane on the image plane 8, which defines an angle different from 90° relative to the optical axis. This will be explained below with reference to the FIGS. 4 and 5.
FIG. 4 is a schematic view of a section from a modification of the second embodiment. Here elements identical with those illustrated in FIG. 2 are identified by the same reference numerals so that a repeated discussion may be dispensed with here. With the normal position of the front-[0036] surface reflector 11, the recording lens 1 creates a sharp image of the object plane B, which is orthogonal on the optical axis 9, in the image plane B′. The intermediate image B′ is projected into the second intermediate image plane B″ by the relay lens 3. As a result the optical path is deflected by the elements 11 and 13—as has been explained above with reference to FIG. 2.
When the object a-b to be recorded is located in the plane B[0037] _s, which is “oblique” relative to the optical axis 9, rather than in the orthogonal plane, an image of this object is produced in the equally “oblique” planes B_s′ or B_s″, with the normal position of the front-surface reflector 11, so that it cannot be sharply focussed into the image plane 8.
In accordance with the present invention the front-[0038] surface reflector 11 is now (also) rotatable independently of the recording lens 1. When the angular position of the reflector 11 is varied from the value x1 as indicated in FIG. 4 to the value x2 (FIG. 5) the plane B_s′ is projected onto the plane B″ orthogonal to the optical axis, due to the pivoting angle x3. As a result it is possible to focus a plane inclined relative to the optical axis sharply on the image plane.
As has already been mentioned, FIG. 6 illustrates an embodiment for the compensation of the image position, as provided by the present invention. Elements identical with those shown in the previously discussed figures are again identified by the same reference numerals so that a repeated description may be dispensed with. A [0039] bevel crown gear 16, which is connected to a pivoting head 15, drives the conical gear wheel 17 when the head is pivoted. This conical gear wheel is fixedly connected to a gear 18, which drives the tube 20 via the gearing 19. The prism 14, which is a Pechan-type prism in the illustrated embodiment, is rotated via the differential gear, the gearing 21, the conical gear wheel 22 and the bevel crown gear 23, at half the pivoting rate relative to the rotating speed of the pivoting head 15. Hence the image is not rotated on the plane 5.
It is possible to employ any other gearing instead of the gear set illustrated here, provided that this gearing has a gear transmission ratio correspond to that of the respective prism used. The gear set shown here is, however, particularly space-saving. [0040]

Claims

1. Optical auxiliary system for a camera, which is inserted between a recording objective (1) and a camera body and which comprises a relay system consisting of the three lenses (3, 4, 6) and the zoom lens (7) for projecting the image from the recording lens onto the film (8) or the video pick-up,

characterised in that the lenses of said relay system (3, 4, 6 and 7) are so structured that they produce more than one image, with the object being projected into a second intermediate image plane (5 or B″), and that the lens disposed directly on said camera body is a zoom lens (7).

2. Optical auxiliary system according to

claim 1

, characterised in that a path-folding unit (11, 13) is disposed between said recording lens (1) and said relay system (3, 4, 6 and 7).

3. Optical auxiliary system according to

claim 2

, characterised in that said path-folding unit (11, 13) comprises two elements whereof at least one deflects the light path by 90°.

4. Optical auxiliary system according to

claim 3

, characterised in that said one element is a front-surface reflector (11) while the other element is a path-folding element (13) with image inversion.

5. Optical auxiliary system according to

claim 4

, characterised in that said front-surface reflector (11) is disposed for rotation about an axis (12) orthogonally on the optical axis (10) of the system and is rotatable relative to said recording lens (1) in such a way that an oblique object plane (Bs) will be sharply focused onto said image plane (8).

6. Optical auxiliary system according to

claim 5

, characterised in that said path-folding element with image inversion is a roof system (13).

7. Optical auxiliary system according to any of the

claims 3

to

6

,

characterised in that an element (11) is rotatable together with said recording lens (1) in such a way that the respective pivoting angle of said recording lens corresponds to twice the pivoting angle of said pivotable element.

8. Optical auxiliary system according to

claim 7

, characterised in that said pivotable element is said front-surface reflector (11).

9. Optical auxiliary system according to

claim 8

, characterised in that a prism (14) is disposed for image rotation between said first lens (3) and said second lens (4).

10. Optical auxiliary system according to

claim 9

, characterised in that said prism (14) is a Pechan-type or Dove-type prism.

11. Optical auxiliary system according to

claim 10

, characterised in that a gearing is provided which drives said prism in such a way that the image position will not be varied.

12. Optical auxiliary system according to any of the

claims 9

to

11

,

characterised in that said two lenses (4, 6), which are disposed between said prism (14) for image rotation and said zoom lens (7), present the same configuration, and that said two lenses are disposed therebetween in symmetry relative to the centre plane.

13. Optical auxiliary system according to any of the

claims 1

to

12

,

characterised in that said zoom lens (7) is a varifocal lens.