JPH0455808A - Conversion lens device - Google Patents

Abstract

PURPOSE:To rapidly and easily attain the wider angle and higher magnification of a zoom lens and to enhance operability by constituting the conversion lens device in such a manner that an afocal lens system is constituted by combination with a micro-wide converter of a negative power and that a teleconverter of a positive power can be mounted on the front face of the micro-wide converter. CONSTITUTION:The macro-wide state much wider in angle that at the wide end in an ordinary zoom region is obtainable if the micro-wide converter 21 is inserted to the front face of the zoom lens 3 at the time of using this lens in the macro region. The afocal optical system (Galilean type telescopic optical system) is constituted by the combination of this teleconverter 23 and the micro- wide converter 21 is the teleconverter 23 is further mounted to the front face of the micro-wide converter 21 in the state of using the micro-wide converter 21. The higher magnification of the zoom lens is promptly and easily attained in this way and the operability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a conversion lens device used to further improve the variable power function of a zoom lens.

[Conventional technology]

Recently, zoom lenses for video cameras are used not only in the normal zoom range from the telephoto end to the wide end, but also with a macro function that allows you to focus on close objects. has been done. Some of these zoom lenses are designed so that when focusing in the macro range, the variable power lens is moved to the wide end, and only the correction lens is moved for focusing. . According to this method, it is possible to focus in the macro range simply by rotating the cam barrel, making it easy to operate.In addition, by combining it with the TTL method-to-focus device, it is possible to focus from the normal zoom range to the macro range. It is also possible to automatically adjust the focus up to that point.

With the above-mentioned zoom lens with a macro function, when used in the macro range, a macro wide converter with negative power is inserted in the front of the zoom lens to further widen the angle of view at the wide end (approximately 0°7x). This macro wide focusing can be performed in exactly the same way as focusing in the macro range by using the correction lens as a focusing lens, so there is no need to provide a new focusing mechanism. , you can easily improve the functionality of your zoom lens.In addition to regular macro photography, when using this macro wide mode, the depth of field is greatly expanded, allowing you to focus on subjects from around 1 meter to infinity. It is also possible to obtain a suitable pan focus state, making it more versatile than using conventional wide conversion lenses.

[Problem to be solved by the invention] By adding the macro wide function described above, it is relatively easy to improve the performance on the wide side of a zoom lens, but conversely, it is difficult to increase the magnification of the zoom lens. Until now, a separately prepared teleconverter had to be attached to the front of the zoom lens. However, until now, the macro wide function by using the macro wide converter mentioned above has not been considered at all, so when using a teleconverter, the macro wide converter must be removed before attaching the teleconverter, and the operation cannot be performed. It had the disadvantage of being bad.

[Purpose of the invention]

The present invention has been made to solve the problems of the prior art described above, and it can quickly and easily widen the angle of a zoom lens.
An object of the present invention is to provide a conversion lens device capable of achieving high magnification.

[Means to solve the problem]

In order to achieve the above object, the present invention attaches a positive power teleconverter to the front of a macro wide converter so that an afocal lens system is constructed by combining it with a negative power macro wide converter used for macro wide converters. It is configured so that it can be done.

[Function] When using a zoom lens in the macro range, inserting a macro wide converter in front of the zoom lens makes it possible to obtain a macro wide state with a wider angle than the wide end in the normal zoom range. If you attach a teleconverter to the front of the macro wide converter while using the macro wide converter, the combination of the teleconverter and the macro wide converter will form an afocal optical system (Galilean telescope optical system). , it becomes possible to immediately achieve high magnification of a zoom lens.

Hereinafter, the present invention will be explained according to the illustrated embodiments.

〔Example〕

In FIG. 1, a video camera 2 has a built-in zoom lens 3 as a photographic lens, and can change magnification by driving a zoom motor by operating a seesaw lever 4 and rotating a cam barrel. Figure 3 (A), (B
) schematically shows the position of each lens at the tele end and wide end in the normal variable power range, and the arrows PI and Ql indicate the positions of the variable power lens 5. in the optical axis direction, respectively. The amount of movement of the correction lens 6 is shown. Focusing in a normal zoom range is performed by moving the front lens 7, and its movement is controlled by a TTL autofocus device. In the figure, reference numeral 8 indicates an iris, reference numeral 9 indicates a master lens, reference numeral 10 indicates an optical low-pass filter, and reference numeral 11 indicates an image sensor. Also, the first
Reference numerals 12 and 13 in the figure indicate a zoom lever and a focus knob for manual operation, respectively.

When used in the macro range, the cam cylinder is further rotated beyond the wide end toward the macro end position shown in FIG. 3(C). Then, while leaving the variable power lens 5 at the wide end position as shown by arrow P2, use the correction lens 6 as a lens for focusing in the macro range, and extend this correction lens 6 as shown by arrow Q2. You can adjust the focus as you go. therefore,
When focusing is not possible in the normal zoom range, by rotating the cam barrel until focus is detected by the autofocus device, the camera can cover the range from infinity to the macro end (for example, several aa). It is also possible to automatically adjust the focus. As shown in FIG. 1, a screw 16 is formed on the inner wall of the photographing opening of the front cover 15 of the zoom lens 3, so that filters can be attached thereto.

By screwing the screw 18 into the screw 16, the conversion lens device 20 can be attached to the front surface of the zoom lens 3. The conversion lens device 20 consists of a rear lens barrel 22 that holds a macro wide converter 21 with negative power, and a front lens barrel 24 that holds a teleconverter 23 with positive power, which are connected by screws 22a, 24.
By screwing the parts a together, the parts can be connected as shown in FIG. And when these are connected,
The focal position of the teleconverter 23 coincides with the focal position of the macro wide converter 21, and the luminous flux (luminous flux diameter φ1) incident on the teleconverter 23 parallel to the optical axis is converted into a parallel luminous flux (luminous flux diameter φ2) by the macro wide converter 21. and is ejected. Therefore, when the rear group lens barrel 22 and the front group lens barrel 24 are connected, it becomes an afocal teleconversion lens (magnification φ1/φ2).

FIG. 3(D) shows a state in which only the macro wide converter 21 is attached to the front surface of the zoom lens 3. A macro wide function can be obtained by inserting a negative power macro wide converter 21 in the front with the variable magnification lens 5 held at the wide end position. In this macro wide mode, a negative power macro wide converter 21 is inserted in front of the zoom lens 3, so focusing is required. In this case, too, the correction lens 6 is used as a focusing lens, and the By moving the lens in the optical axis direction within a certain range, it is possible to focus on a nearby subject.

The close distance at macro wide is, for example, 7 cm when the close distance at the macro end shown in Figure 3 (C) is 5 cm.
cm, which narrows the possible close-up range, but on the other hand, not only can the angle of view be widened, but depending on the adjustment position of the correction lens 6 in arrow Q2, the depth of field can be extended from around 1 m to infinity. It is also possible to obtain a pan-focus state that covers the inside.

When the macro wide converter 21 is attached to the front of the zoom lens 3 and the teleconverter 23 is further attached to the front as shown in FIG. A version lens is configured. This teleconversion lens is an afocal type and does not affect the imaging position of the master lens 9 of the zoom lens 3, so the variable magnification lens 5. PL the correction lens 6,
Zooming can be performed by moving within the normal zoom range indicated by Ql, and focusing can be performed by moving the front lens 7 in the same way as during normal zooming. And in this case,
It becomes possible to further increase the magnification of the zoom lens 30 when the conversion lens device 20 is not used. Note that if only the teleconverter 23 is placed in front of the zoom lens 3, the zoom lens 3 cannot be used for focusing, so the screw 24a of the front lens barrel 24 must be screwed into the screw 16 of the front cover 15. It is better to make it so that it cannot be done.

As mentioned above, the macro wide converter 21 is made separable from the conversion lens device 20,
The macro wide function is obtained by attaching only the macro wide converter 21, and the tele conversion lens is configured when the tele converter 23 is attached in front of the macro wide converter 21, thereby giving the zoom lens 3 the macro wide function. At the same time, the teleconverter 2 provides φ1 such that the value of φ]/φ2, which is the magnification of the conversion lens, is, for example, 1.5 times, 2°0 times, and 2.5 times.
If you prepare 3, you can easily increase the magnification and it is very convenient.

FIG. 4 shows an example in which the macro wide converter 21 described above is built into the video camera 2.

In this embodiment, the macro wide converter 21 is slidably housed within the front cover 15, and in the illustrated state, the zoom lens 3 is used in a normal zoom range. By arranging the macro wide converter 21 in front of the zoom lens 3, the macro wide state shown in FIG. 3(D) can be obtained similarly to the embodiment described above.

A screw 26 is cut into the inner wall of the photographing opening of the front cover 15, and a screw 27a formed at the rear end of the lens barrel 27 can be screwed into the screw 26. Since the teleconverter 23 described above is built into the lens barrel 27, when the macro wide converter 21 is inserted into the front of the zoom lens 3 and the lens barrel 27 is screwed to a predetermined position, the macro wide converter 21
The focal position of the teleconverter 23 matches the focal position of the teleconverter 23, and an afocal teleconversion shown in FIG. 3(E) is constructed. In this embodiment as well, if several types of teleconverters 23 with different focal lengths are prepared and the length of the screw 26 and the screw 27a are limited in accordance with each focal length, It becomes possible to change the magnification φ1/φ2 of the teleconversion lens in steps.

The present invention has been described above according to the illustrated embodiment, but the embodiment shown in FIG. You can do it however you like. Furthermore, the present invention is not limited to zoom lenses in which the front lens is used for focusing in the normal zoom range, and the correction lens is used as a focusing lens when used in the macro range; In addition to front focus 2 zoom lenses that focus over the entire area with just the lens alone, it can also be used with inner focus or rear focus zoom lenses that focus by extending the correction lens or master lens.

[Effects of the Invention] As explained above, according to the conversion lens device of the present invention, not only can a macro wide function be obtained by attaching a negative power wide converter to the front of the zoom lens, but also the wide converter By combining a positive power teleconverter on the front surface, an afocal teleconversion lens is constructed, making it possible to easily increase the magnification of the zoom lens.

Furthermore, it is also possible to incorporate the wide converter or even the teleconverter that constitutes the conversion lens device of the present invention into the zoom lens device, and in this case, it becomes possible to further improve the operability.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a state in which the conversion lens device of the present invention is used in combination with a zoom lens of a video camera. FIG. 2 is a sectional view of the conversion lens device of the present invention. FIGS. 3A to 3E are explanatory diagrams showing the lens arrangement of the zoom lens in its normal usage state and in its usage state when combined with a conversion lens device. FIG. 4 is an external view showing another embodiment of the present invention. 3...Zoom lens 20...Conversion lens device 21...Wide converter 23...Tele converter

Claims (2)

[Claims] (1) In a conversion lens device for a zoom lens that allows focusing in the macro range with the variable magnification lens moved to the wide side, it is possible to focus in the front of the zoom lens with the variable magnification lens moved to the wide side. There is a macro wide converter with negative power that further expands the angle of view on the wide side by moving the focus lens and further widening the angle of view on the wide side. A conversion lens device comprising a positive power teleconverter that forms an afocal lens system in combination. (2) A zoom lens that allows focusing in the macro range by moving the focusing lens with the variable magnification lens moved to the wide side, and a zoom lens that allows focusing in the macro range with the variable magnification lens moved to the wide side. A conversion lens device for a zoom lens device consisting of a macro wide converter with negative power that further widens the angle of view on the wide side by being inserted into the front, and which can be freely attached to and removed from the front of the macro wide converter when the macro wide converter is inserted. A conversion lens device comprising a positive power teleconverter that forms an afocal lens system in combination with a macro wide converter.