JPH06235859A - Zoom lens having variable power range - Google Patents

Abstract

PURPOSE:To attain a new zoom lens having variable power range and capable of enlarging a focal distance variable range of the zoom lens to two enlarged ranges which are different from the variable range peculiar to a master lens though a converter lens of one kind is added. CONSTITUTION:The zoom lens provided with at least two groups 1 and 2 and for changing a focal distance by moving two or more groups 1 and 2 on an optical axis becomes a master lens, and a converter lens 3 is inserted in between the groups of the master lens, or an optional position between the final lens and an image forming plane, and the focal distance is changed within a 1st enlargement range by moving the movable groups 1 and 2 of the master lens on the optical axis with the converter lens 3 fixed, and then, the converter lens 3 inserting position is shifted, the focal distance is changed within the 2nd enlargement range by moving the movable groups 1 and 2 of the master lens on the optical axis with the converter lens 3 fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens having a variable magnification range. The zoom lens of the present invention can be used as a zoom lens for an LS camera or a single lens reflex camera.

[0002]

2. Description of the Related Art A zoom lens has a variable focal length and can change a photographing range, but the variable range of the focal length is limited, and various methods for expanding the focal length range have been proposed conventionally.

As a method of enlarging the focal length range of a zoom lens, a converter lens is added to the master lens and the master lens is zoomed so that the focal length is continuous within a range (enlarging range) different from the variable range of the master lens. Method (Japanese Patent Laid-Open No. 63-55509,
(Japanese Patent Laid-Open No. 2-219011, etc.) or a method in which the inserted converter lens and the master lens are zoomed to continuously change the focal length in an expansion range different from the variable range of the master lens (Japanese Patent Laid-Open No. 2-19011) 59709) or a method in which an arbitrary group of master lenses is replaced with an interchangeable lens group for zooming and the focal length is continuously changed within an enlargement range different from the variable range of the master lens (JP-A-60- No. 208722) is known.

However, in any of the above-mentioned methods, the expansion range of the focal length obtained by using the converter lens or the interchangeable lens group is only "1 range".

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and the focal length variable range of the zoom lens is the same as the variable range of the master lens although the converter lens to be added is one kind. Aims to provide a new zoom lens with a variable zoom range that can be expanded into two different expansion ranges.

[0006]

In the zoom lens having a variable magnification range variable according to the present invention, the master lens has "at least two groups, and the focal length is changed by moving two or more groups on the optical axis. “Zoom lens”, and one type of converter lens is used for expanding the focal length range.

In the zoom lens according to the first aspect, "a converter lens is inserted between the groups of the master lens or between the final lens and the image plane, and the moving group of the master lens is fixed to the optical axis. Move it up to change the focal length in the first enlargement range, change the insertion position of the converter lens, move the moving group of the master lens on the optical axis with the converter lens fixed, and change the focal length to the second position. It changes in the expansion range of.

In the zoom lens according to the second aspect, "a converter lens is inserted between the groups of the master lens or between the final lens and the image plane, and the moving group of the converter lens and the master lens is arranged on the optical axis. By moving the focal length in the first expansion range, changing the insertion position of the converter lens, and moving the converter lens and the master lens moving group on the optical axis to change the focal length in the second expansion range. It is characterized by changing with.

[0009]

As described above, in the present invention, when the "expansion range of the focal length different from the variable range of the focal length of the master lens" is realized, the converter lens is added to the master lens, but the insertion position of the converter lens is There are two different positions, and the basic group arrangement of the master lens and the converter lens differs depending on each insertion position.

In each group arrangement, the moving group of the master lens is changed along the optical axis (claim 1), or the moving group of the converter lens and the master lens is moved along the optical axis. The focal length can be changed within the expansion range according to each basic group arrangement.

[0011]

EXAMPLE FIG. 1 shows an example of a zoom lens with variable magnification range according to the first aspect. In this example, FIG.
As shown in (a), the master lens includes a first group 1 having a positive power and a second group 2 having a negative power.
In the normal zoom range, that is, in the variable range of the focal length by only the master lens, the first group 1 and the second group 2 are moved along the optical axis to change the focal length.

That is, when zooming from wide angle to telephoto,
Both the first group 1 and the second group 2 are extended toward the object side (left side in FIG. 1).

In order to expand the variable range of the focal length to the "first expansion range" other than the variable range of the master lens, the converter is arranged between the groups of the master lenses or between the final lens and the image plane. Although a lens is inserted, in this embodiment, as shown in FIG. 1B, a converter lens 3 which is a negative lens is inserted as a converter lens between the final lens of the master lens and the image plane (first lens). Insertion position).

Then, the first lens group 1 and the second lens group 2 of the master lens are moved along the optical axis while the converter lens 3 is fixed to change the focal length in the first enlargement range.
Even in this first enlargement range, the first lens group 1 and the second lens group 2 of the master lens are extended toward the object side, so that zooming from the wide-angle side to the telephoto side is performed.

To realize the "second expansion range", FIG.
As shown in (c), the converter lens 3 is moved to a position (second insertion position: shown by a solid line) different from the position (position shown by a broken line) when realizing the first expansion range. In this embodiment, the converter lens 3 is the first master lens.
It is inserted between the group 1 and the second group 2.

In this state, the first lens group 1 and the second lens group 2 of the master lens are moved on the optical axis while the converter lens 3 is fixed, and the variable range of the master lens and the first expansion range are different. The focal length is changed in the second enlargement range.

In this embodiment, two positive and negative zoom lenses are used as the master lens, but any type of master lens may be used as long as it has two or more zoom lenses. The number of constituent lenses may be arbitrary, and the insertion position of the converter lens with respect to the master lens may be an arbitrary position between the groups of the master lens or between the final lens and the film surface.

FIG. 2 shows an embodiment of the zoom lens having a variable magnification range according to the second aspect. The master lens is shown in Figure 2 (a).
Also in this embodiment, as shown in FIG. 2, 2 consisting of the first group 1 having positive power and the second group 2 having negative power.
In the normal zoom range, the first group 1 and the second group
The focal length is changed by moving the group 2 and the optical axis. That is, when the magnification is changed from the wide angle to the telephoto, both the first group 1 and the second group 2 are extended toward the object side (left side in FIG. 2).

In order to expand the variable range of the focal length to the "first expansion range" other than the variable range of the master lens, the converter is arranged between the groups of the master lenses or between the final lens and the image plane. Although a lens is inserted, in this embodiment, as shown in FIG. 2B, a converter lens 3 which is a negative lens is inserted as a converter lens between the final lens of the master lens and the image plane (first lens). Insertion position).

Then, as shown in FIG. 2 (b), the converter lens 3 and the first and second groups 1 and 2 of the master lens are moved along the optical axis to adjust the focal length in the first enlargement range. Change. Even in this first enlargement range, the first lens group 1 and the second lens group 2 of the master lens are extended to the object side together with the converter lens 3, so that zooming from the wide angle side to the telephoto side is performed.

To realize the "second expansion range", the process shown in FIG.
As shown in (c), the converter lens 3 is moved to a position (second insertion position: shown by a solid line) different from the position (position shown by a broken line) when realizing the first expansion range. In this embodiment, the converter lens 3 is the first master lens.
It is inserted between the group 1 and the second group 2.

In this state, the converter lens 3 and the first lens group 1 and the second lens group 2 of the master lens are moved along the optical axis to change the focal length in the second enlargement range.
Also in this second enlargement range, the first lens group 1 and the second lens group 2 of the master lens are extended to the object side together with the converter lens 3, so that zooming from the wide angle side to the telephoto side is performed.

In this embodiment, two positive and negative zoom lenses are used as the master lens, but any type of master lens may be used as long as it has two or more zoom lenses. The number of constituent lenses may be arbitrary, and the insertion position of the converter lens with respect to the master lens may be an arbitrary position between the groups of the master lens or between the final lens and the film surface.

[0024]

As described above, according to the present invention, it is possible to provide a novel zoom lens having a variable zoom range. Since the zoom lens according to the present invention has the above-mentioned configuration, the first and second magnifying portions other than the focal length variable range peculiar to the master lens are provided, although the converter lens to be added to the master lens is only one type. In the range, the focal length can be continuously changed.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of the invention according to claim 1;

FIG. 2 is a diagram for explaining one embodiment of the invention according to claim 2;

[Explanation of symbols]

 1 First group of master lens 2 Second group of master lens 3 Converter lens

Claims (2)

[Claims] 1. A master lens is a zoom lens which has at least two groups and whose focal length is changed by moving two or more groups on the optical axis, and between the groups of said master lenses or the final lens and an image plane. A converter lens is inserted at an arbitrary position between them, and while the converter lens is fixed, the moving group of the master lens is moved on the optical axis to change the focal length in the first expansion range. Variable zoom range zoom lens characterized in that the focal length is changed in the second enlargement range by changing the insertion position and moving the moving group of the master lens on the optical axis while fixing the converter lens. . 2. A zoom lens which has at least two groups and whose focal length is changed by moving two or more groups on the optical axis is used as a master lens, and between the groups of the master lenses or a final lens and an image plane. A converter lens is inserted at an arbitrary position between them, and the converter lens and the moving group of the master lens are moved on the optical axis to change the focal length in the first enlargement range, and the converter lens insertion position. The zoom lens having a variable magnification range, characterized in that the focal length is changed in the second enlargement range by moving the converter lens and the moving group of the master lens on the optical axis.