JPH0533374B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a zoom lens having a tilting mechanism.

(Background of the Invention) When the subject to be photographed is on a slope, such as a building seen diagonally, or when the photographing position must be taken without being able to face the subject directly, it is necessary to take all photographs. It is known that if you want to obtain a focused image of a subject on the screen, you can use a so-called tilting mechanism. However, when a tilting mechanism is incorporated into a zoom lens, the following disadvantages occur. In other words, if you set the zoom lens to a certain focal length, adjust the distance ring and tilting mechanism to obtain a fully focused subject image, and then zoom (change the focal length), the tilting mechanism will change each time. It is necessary to readjust the adjustment, which is very troublesome. For this reason, a zoom lens equipped with a tilting mechanism has not yet been commercialized.

Furthermore, if a zoom lens having this tilting mechanism is applied to a television camera, the screen will appear out of focus every time the lens is zoomed, making it unsightly and thus impractical.

(Object of the Invention) The present invention operates the zoom ring to set the zoom lens to a certain focal length, adjusts the distance ring and tilting mechanism to obtain an in-focus subject image on the entire screen, and then zooms. The aim is to realize a zoom lens with a tilting mechanism that can automatically obtain a focused subject image on the entire screen even when the focal length is changed. An object of the present invention is to realize a zoom lens having a tilting mechanism that does not require focusing every time.

(Summary of the Invention) The present invention provides the following features: the shooting distance of a zoom lens that is initially set in a focused state over the entire screen;
If the focal length is changed by zooming after that, the tilt amount correction amount is calculated from the focal length change amount and the memorized value, and the tilt mechanism is operated to automatically adjust the tilt angle. The technical point is to maintain focus across the entire screen.

(Example) FIG. 2 is a plan view illustrating the principle of the present invention, which uses a left-right deflection device (hereinafter referred to as a left-right swing mechanism) among various tilting mechanisms. The swing mechanism is a mechanism that allows a member to which a lens is attached to rotate around a vertical axis, and the mechanism that allows the member to rotate around a horizontal axis is a vertical tilting device (hereinafter referred to as a vertical tilt mechanism). ).

The present invention is of course applicable to a zoom lens having a swing mechanism and a tilt mechanism, and is also applicable to various other tilting mechanisms, but for the sake of simplicity, only the left-right swing mechanism will be described here.

In Figure 2, 1 is the rear principal plane of the zoom lens, and 1' is the initial setting where the entire screen is in focus, and then the new state when the focal length is changed due to zooming. The posterior principal plane is shown. d is the difference between the two rear main planes 1 and 1'.
Reference numeral 2 denotes an image plane, which is, for example, an image pickup plane of an image pickup device such as a television camera. 3 is a subject, and 3a and 3b indicate subjects at both ends of the screen, respectively. Θ is the swing angle at the initial setting, and at the time of the initial setting, the rear principal plane 1
The extension lines of the straight line connecting the image plane 2 and the subjects 3a and 3b intersect at an intersection 4.

Now, if you zoom from the initial settings and move the zoom lens from the rear principal plane 1 to 1', if the swing angle Θ remains the same, the extension line of the rear principal plane 1' will not intersect with the intersection 4, and the initial The entire screen will be out of focus, and an out-of-focus portion will appear on the screen. Therefore, if the swing angle Θ is corrected by ΔΘ to 1" and the extension line of the rear principal plane 1" intersects the intersection 4, the initial setting state, that is, the focus is maintained over the entire screen. It becomes a state of ivy.

FIG. 3 is a diagram showing an example of the relationship between the movement amount d of the rear principal plane due to zooming and the swing angle correction amount ΔΘ, where the parameter is the swing angle Θ.
However, according to FIG. 3, the larger the swing angle Θ, the smaller the swing angle correction amount ΔΘ, but this relationship varies depending on each zoom lens and is not constant. However, since this relationship is fixed for each zoom lens, it is necessary to provide means for calculating the swing angle correction amount ΔΘ from the swing angle Θ and the movement amount d of the rear principal plane due to zooming, or The swing angle correction amount ΔΘ may be calculated in advance from the movement amount d of the principal plane, stored, and read out as necessary.

FIG. 1 is a block diagram showing one embodiment of the present invention, 5 is a zoom mechanism, 6 is a tilt mechanism, 7 is a distance adjustment mechanism, 8 is a zoom amount detection mechanism, 9 is a tilt amount detection mechanism, and 10 is an analog 11 is an initial setting means, 12 and 13 are storage means, 14 is a subtraction means, and 15 is a tilt correction amount determining means consisting of a ROM-TABLE. The storage means 12 and 13 store the states of the zoom mechanism 5 and the tilting mechanism 6 when the initial setting means 11 is operated. After the storage, the analog switch 10 is switched as shown by the dotted line, and the output of the zoom amount detection mechanism 8 is applied to the subtraction means 14.

Next, the operation will be explained. After adjusting the zoom mechanism 5, tilt mechanism 6, and distance adjustment mechanism 7 so that the entire screen is in focus, operate the initial setting means to adjust the status of the zoom mechanism and tilt mechanism 6 to each detection mechanism 8, 9, each storage means 12,1
Store in 3. After the memory, analog switch 1
0 is switched, and the subtraction means 14 detects the presence or absence of zooming. When the zoom mechanism 5 is operated for zooming, the output of the zoom amount detection mechanism 8 is inputted to the subtraction means 14 via the analog switch 10, and the amount of movement d of the rear principal plane is determined based on the difference from the initial setting. It is input to the amount determining means 15. The tilt correction amount determining means 15 includes a ROM-
The tilt correction amount ΔΘ determined by the tilt amount Θ and the movement amount d of the rear principal plane is stored in TABLE in advance, and the correction amount ΔΘ is given to the tilt mechanism 6, the tilt amount is corrected, and the tilt amount is corrected over the entire screen. The camera will automatically maintain focus. Therefore, unless the distance adjustment mechanism 7 is changed, even if the zoom mechanism 5 is operated, no operation is required, and the initial setting state, that is, the focused state is automatically maintained over the entire screen. It will be done. Therefore, especially when applied to a television camera, the entire screen is kept in focus at all times even during zooming, making it possible to change the screen appropriately without making the screen unsightly. Operating the TV camera is also extremely easy.

In the above embodiment, the tilt correction amount determining means 15
Although shown here is a configuration made up of ROM-TABLE, for example, the correction curve shown in FIG. 3 determined by each zoom lens can be created using an analog circuit, and this correction It may be configured to calculate ΔΘ based on the curve.

(Effects of the Invention) As explained above, according to the present invention, the zoom ring is operated to set the zoom lens to a certain focal length, and the distance ring and tilting mechanism are adjusted to capture an in-focus subject image on the entire screen. , perform initial settings, memorize the zoom state and tilt state at the time of initial settings,
The configuration is configured to detect the amount of subsequent change in the zoom status and automatically correct the tilt amount, so even if you zoom (change the focal length) after making the initial settings, the camera will automatically fill the entire screen. It is possible to realize a zoom lens having a tilting mechanism that can obtain a focused subject image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a plan view illustrating the principle of the present invention, and FIG. 3 is a diagram showing an example of the relationship between the movement amount d of the rear main plane due to zooming and the swing angle correction amount ΔΘ. (Explanation of main parts), 5...Zoom mechanism, 6...
...Tilt mechanism, 7... Distance adjustment mechanism, 8, 9...
Detection mechanism, 10...Analog switch, 11...
Initial setting mechanism, 12, 13... Storage means, 14...
. . . subtraction means, 15 . . . tilt correction amount determination means.

Claims (1)

[Scope of Claims] 1. In a zoom lens equipped with a tilting mechanism, a storage means that is initially set when an in-focus subject image is obtained on the entire screen and stores the tilting amount and focal length at the time of the initial setting. , a detection means for detecting a change in focal length when zooming is performed after the initial setting, a correction amount determination means for determining a correction amount for the amount of tilt based on the output of the detection means, and a correction amount determination means for determining a correction amount for the amount of tilt based on the output of the detection means. A zoom lens equipped with a tilting mechanism, characterized by comprising a correction means for controlling and correcting the tilting mechanism according to the output. 2. A zoom lens equipped with a tilting mechanism according to claim 2, wherein the correction amount determining means is a correction amount determining device based on a ROM-TABLE.