JPH07109472B2 - Short range warning device for varifocal camera - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a short-distance warning device for a variable-focus camera.

(Background of the Invention) While a variable focus camera such as a bifocal camera is capable of shooting a telephoto image extremely easily, a general user who is unfamiliar with the camera is apt to shake in a telephoto state, and particularly in a short distance shooting where the magnification becomes large. There was a drawback that the blur was noticeable.

(Object of the Invention) An object of the present invention is to solve this drawback and provide a warning device capable of warning whether or not the distance to an object to be actually photographed is a blur-prone distance according to the focal length.

(Summary of the Invention) In order to achieve such an object, the present invention provides a short-distance warning device for a camera capable of changing the focal length of a photographing lens, by measuring the distance to a subject and determining the distance to the subject. Distance measurement signal output means for outputting a corresponding distance measurement signal, identification signal output means for outputting an identification signal corresponding to a focal length, and a blur limit shooting distance set to be longer as the focal length is longer are stored. The camera is connected to the storage device, the distance measurement signal output means, the identification signal output means, and the storage means, reads out the blurring limit shooting distance corresponding to the focal length from the storage means, and reads out the blurring limit shooting distance and the ranging signal from the storage means. And a warning hand that outputs a warning signal when the distance to the subject is equal to or less than the blur limit shooting distance read from the storage means and a warning signal that is issued by the warning signal of the output means. And a step.

(Embodiment) FIG. 1 is a block diagram of a first embodiment of the present invention applied to a camera capable of switching the focal length of an objective lens in two steps.

The camera body 1 is a film winding device, a release switch,
It has a shutter and the like, and further has an objective lens that can switch between tele (for example, 70 mm) and wide (for example, 35 mm). Switching of the objective lens is performed by the lens transfer device 3 controlled by a control signal from the CPU 2. Switching between tele and wide is commanded from the outside by the T / W selector switch 4. When the changeover switch 4 is on, it indicates tele, and when it is off, it indicates wide. The former is input with a low level signal to the CPU 2 and the latter is input with a high level signal to the CPU 2. The distance measuring device 5 measures a distance to a subject, outputs a distance measuring signal and inputs it to the CPU 2, and its operation is controlled by a command from the CPU 2. The storage device 6 stores the blurring limit shooting distance l ₁ when the objective lens is telescopic and the blurring limit shooting distance l ₂ (<l ₁ ) when the objective lens is wide, and is read out as appropriate by a command from the CPU 2. Be done. The warning device 7 is controlled by the CPU 2 and issues a warning in a visual or auditory manner.

Next, the operation of the embodiment shown in FIG. 1 will be described based on the flow chart of the CPU 2 shown in FIG.

First, the photographer selects either tele or wide by the changeover switch 4. The CPU 2 appropriately reads the state of the changeover switch 4, inputs a tele / wide selection signal to the lens moving device 3, and sets the tele / wide of the objective lens (step 30 in FIG. 2). Next, the photographer turns on the release switch of the camera body 1. When a so-called half-push switch is used as the release switch, a half-push signal is input to the CPU 2 in the half-push state (step 20). When the half-press signal is input, the CPU 2 issues a distance measurement command to the distance measuring device 5. The distance measuring device 5 measures the distance to the subject and inputs the distance measuring signal to the CPU 2 (step 21).

The CPU 2 then determines the short-distance warning. Ie CP
U2 stores the distance measurement value R from the distance measuring device 5 in the storage device 6 in step 21, and then reads the state of the changeover switch 4 to determine whether the tele or wide is selected (step 22). . When the tele is selected, the blur limit shooting distance l ₁ when the tele is stored in the storage device 6
And the distance measurement value R are read out and compared (step 23). l ₁ <
In the case of R, the distance to the subject is longer than the blurring limit shooting distance, so no warning is issued and a signal for adjusting the shooting lens to the in-focus position is output to the lens moving device 3 (step
twenty four). After that, when the release switch of the camera body 1 is completely pressed (step 25), a shutter control signal is input to the shutter of the camera body 1 to perform exposure control (step 26).

On the other hand, if l ₁ ≧ R in step 23, the distance to the subject is equal to or less than the blur limit shooting distance, so in step 27 a warning signal is output to the warning device 7 to generate a warning. If the distance measurement value R is less than or equal to the short range shooting limit L (step 2
8) The CPU 2 outputs a signal for locking the release switch of the camera body 1 to the camera body 1 (step 29), otherwise moves the lens in step 24, and the camera body 1
When the release switch is completely pressed, the shutter control signal is input to the shutter of the camera body 1 (steps 25 and 26).

Also, when Wide is selected in step 22,
The wide-angle blurring limit shooting distance l ₂ and the distance measurement value R stored in the storage device 6 are read out and compared (step 3).
0). If l ₂ <R, the distance to the subject is longer than the blurring limit shooting distance, so no warning is issued and a signal for adjusting the shooting lens to the in-focus position is output to the lens moving device 3 (step 24). ). After that, when the release switch of the camera body 1 is completely pressed, the shutter control signal is input to the shutter of the camera body 1 (steps 25, 2).
6).

On the other hand, if l ₂ ≧ R in step 30, the distance to the subject is equal to or less than the blur limit shooting distance, so in step 27, a warning signal is output to the warning device 7 to issue a warning. If the distance measurement value R is less than or equal to the short range shooting limit (step 2
8) The CPU 2 outputs a signal for locking the release switch of the camera body 1 to the camera body 1 (step 29), otherwise the lens is moved, and when the release switch of the camera body 1 is completely pushed in, the camera The shutter control signal is input to the shutter of the main body 1 (steps 24 and 2).
5, 26).

In this way, the photographer can obtain a short-distance warning suitable for tele and wide shots, so that the risk of inadvertently performing camera shake photography can be avoided.

It should be noted that, in the above embodiments, a two-stage switching type camera of tele and wide is used as the objective lens, but a zoom type lens may be used by switching the sub-lens in and out of the optical path. In the case of a zoom type lens, it is sufficient to divide the zoom range into stages and input each focal length to the CPU 2 as a code signal by a plurality of switches.

Further, in the above embodiment, the shortest distance photographing is set to be common for the length L in both cases of tele and wide, but of course, this may be set to different lengths L, l ₁ , L ₂
May be equal to the close-up shooting limit.

Furthermore, if the tele is 70 mm and the wide is 35 mm,
If each of the wide-angle blurring warnings has substantially the same image magnification, the conditions for blurring will be the same for tele and wide. Therefore, in the case of wide, it gives a close warning at 35 cm, and at tele (70 mm)
It would be convenient to give a close warning at 70 cm. At this time, the lens may be extended up to 35 cm even during telephoto, or the lens may be stopped at 70 cm during telephoto.

(Effects of the Invention) As described above, according to the present invention, the blurring limit shooting distance that changes depending on the focal length is compared with the subject, and a warning is issued when the distance to the subject is equal to or less than the blurring limit shooting distance. Therefore, it is not necessary to detect a blur using a special mechanical blur detector such as an acceleration detector or a strain gauge. Therefore, the camera can be downsized and the cost can be prevented from increasing.

Further, according to the present invention, when the distance to the subject is equal to or less than the blur limit photographing distance, a warning is always issued, so that the distance to the subject to be actually photographed is easily blurred in the conventional short-distance photographing with a large magnification. It is possible to solve the problem of not being able to understand whether the subject is at a distance and to let the photographer know whether the subject to be photographed is easily blurred. Therefore, it is possible to prevent a general user who is unfamiliar with photographing from accidentally performing blurring photographing.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
It is a figure which shows the flowchart of CPU of a figure. (Description of symbols of main parts) 2 ... CPU (output means) 4 ... T / W changeover switch (identification signal output means) 5 ... Distance measuring device (distance measuring signal output means) 6 ... Storage device (storage) Means) 7 ... Warning device (warning means).

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G03B 17/18 Z (56) References JP-A-55-110234 (JP, A) Actual exploitation Sho 57 -74428 (JP, U) Actual development Sho 59-158133 (JP, U)

Claims (1)

[Claims] 1. A short-distance warning device for a camera capable of changing the focal length of a taking lens, which outputs a distance-measuring signal for measuring a distance to an object and outputting a distance-measurement signal corresponding to the distance to the object. Means, an identification signal output means for outputting an identification signal corresponding to the focal length, a storage device for storing a blur limit photographing distance set to be longer as the focal length is longer, and the distance measurement signal output means Connected to the identification signal output means and the storage means, reads the blurring limit shooting distance corresponding to the focal length from the storage means, and reads the blurring limit shooting distance and the distance measurement signal from the storage means. Output means for outputting a warning signal when the distance to the subject is equal to or less than the blur limit photographing distance read from the storage means, and a warning signal of the output means. Short-range warning device which comprises a a warning means for performing warning by.