DD147880A1 - DISPLAY SYSTEM FOR PHOTOGRAPHIC CAMERAS - Google Patents

Abstract

The invention relates to a display system for photographic cameras with a depth of field information in the viewfinder. Zie + and task is the creation of a display system for cameras with automatic exposure, which ensures a clear and easily recognizable viewfinder information about the current Schaerfentiefe without mechanical transmission gear and Einspiegelungselemente. Gemaesz of the invention finds an electronic computing circuit 4 application, preferably from one to two computer programs for the front and rear Schaerfentiefegreze switchable. Calculator is formed, whose entrances with signalers for the set distance, the preselected or expected aperture magnitudes and the focal length of the object are in communication and dasz at the output of the arithmetic circuit fitting, the limits of the respective Schaerfentiefe characterizing signal values for the display of the Schaerfiefiefebereiches and the recording distance on the one hand and the exposure values on the other hand together, sequentially controllable display are zuführbar.

Description

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VEB PENTACOM DRESDEN Dresden, 27 Nov. 1979

Ke monro and Klncworko Title of the invention

Display system for photographic cameras

Field of application of the invention

The invention relates to a display system for fotografisehe cameras, which informs in the viewfinder on the respective depth of field.

Characteristic of the known technical solutions

It is known to provide the viewfinder of a camera with a range and depth of field indication. For this purpose, an optical or mechanical system brings the set distance to the display and a by means of a threaded spindle along the distance scale movable pair of pointers indicates the depth of field (DL-PS 28 068) ♦ It was also known to make the depth of field by means of two pointers marked »of It is also known to display ranges of distances for close-up shots, images at medium distances and landscape shots by means of light elements controlled by the taking lens in the viewfinder (DE-OS 1 447 564) The former display system requires a space-consuming mechanical transmission system between the lens and the camera.

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Focused depth-of-field indicator is not applicable to interchangeable-lens cameras «The three-distance range indicated means that the depth of field is insufficient.

Object of the invention

The invention is intended to reduce the mechanical complexity and adequately characterize the expected depth of field.

Darl egung the essence of the invention

The object of the invention is to provide a display system which ensures a clear and well-recognizable viewfinder information about the current depth of field in cameras with automatic exposure and interchangeable lenses despite waiving mechanical transmission gear and Einspiegelungselemente between lens and camera and due to its small footprint especially for Compact cameras is suitable ·

According to the invention, this object is achieved in that an electronic calculation circuit, which is preferably formed by a computer switchable to two computer programs for the front and rear depth of field limit, is used whose inputs with signal transmitters for the set distance, the preselected or expected aperture size and the focal length of the lens are in communication and that at the output of the arithmetic circuit adjacent, the limits of the respective depth of field characterizing signal values for the display of the depth of field and the recording distance on the one hand and the exposure *

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on the other hand, common, sequentially controllable display can be fed »

embodiment

The invention will be explained below with reference to exemplary embodiments.

Pig · 1 block diagram

Pig; 2 viewfinder frames with numerical sharpening

depth or exposure display

Pig · 3 viewfinder cutting with one of the scales

for distance and exposure times

associated LED line ·

According to Pig · 1, a sequence control circuit 1 is connected to a depth of field button 2 and a switch 3 which can be actuated by the camera shutter. An output of the sequence control circuit 1 is fed to an electronic arithmetic circuit 4, whose further inputs for supplying signal values which determine the object focal length f , the set distance a and the aperture size k mark, in a manner not shown with a lens provided on the coding and with electrical actuators in conjunction, which are coupled to the setting rings for distance and aperture. A signal u 'corresponding to the diameter of a permissible unsharp circle is also fed to the input of the arithmetic circuit 4. At the outputs of the latter, there are holding circuits 5, 6 for the calculated front and rear sharpening limits, to which a decoder 7 connected to the sequence control circuit and to this one for the display of distance and exposure values common display 8 of, for example, in Figures 2 and 3

The decoder 7 is connected to the sequence control circuit 1. With 9 is an up / down counter for exposure timing, 10 a driver stage, 11 a shutter control solenoid, 12 a D / A converter, 13 an input stage, and denoted by 14 a variable gain amplifier «The display 8 is shown in FIG. 2 by a numeric display panel 15 or according to Fig.'3 formed by an LED row 16. Both display are arranged on viewfinder frame 17 or · 18 * The LED Zei-Ie are Scales 19, 20 assigned for distance and exposure times »

The mode of action is the following:

With the calculation circuit. 4 are two computer programs according to the relationships

a f a ,. = -YY- = (1)

» & £ λ. Ir τι f _n _f ^ X τ K. # U · ^ aI /

_{a =} (2)

ⁿ f - k. u ο (af)

feasible. A ^ denotes the distance which forms the front boundary of the depth of field range, a ^ denotes the rear limit of the depth of field range. The signal values f (z × B × 50 mm), a and k, necessary for the two computer programs are transmitted with the setting rings electrical adjustment links coupled for distance and aperture as well as a coding provided on the interchangeable lens, analog or digital.

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Equipped · The signal u is given as a fixed variable in the calculation circuit. After focusing on a specific object, for example, 1.7 m, and the aperture code, k, for example, 5 »6>, the depth of field button 2 can be operated · About the sequence control circuit 1, the arithmetic circuit 4 for performing the computer program for the front limit The calculated distance a "is stored in the holding circuit 5. Via the feedback of the holding circuit 5 to the sequence control circuit 1, the latter now switches over the arithmetic circuit to the second calculation program for the rear boundary of the depth of field. The calculated

, Te distance a _ß is stored in the latch circuit 6 · iiach concerns of both signals at the decoder 7 to be both the set distance 1.7 m and the calculated depth of focus range limits of 1.5 m and 2.1 m with the disposed on the finder frame display 8 is displayed. This can be done by the numerical display panel 15 according to Pig · 2 or by the fact that according to FIG. 3 LED line 16, which is assigned to the scale 20, drives three LEDs, of which the middle one is the preset distance 1.7 m and the lower one is. Each time the input of the arithmetic circuit 4 is changed, it is reset, a new calculation performed and its results displayed again. This case is possible, for example, when the preset exposure distance is to be changed after taking note of the depth of field so that the object to be imaged moved to the front or rear boundary and the scene foreground or scene background is also sharply mapped. When changing the preselected aperture size or when changing the focal length

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occurs the same effect · With relief of the depth of field button 2 of the described calculation and display process is terminated.

Hunmehr can the camera shutter button is pressed up to a pressure point and thereby the switch 3 closed v / earth · Consequently, a signal value in which the Objektleuchtdich'te B, the aperture size k and the Pilmempfind- probability χ are linked, via the Ablaufschsch -

; tion 1 as a pulse train to the up-down counter 9 out «The pulse supply is terminated as soon as the control amplifier 3 is adjusted due to the feedback via the D / A converter 12. The written into the counter 9 count value corresponds to the expected exposure time, _ζ β example ^1/1000 sec _o The sequence control circuit causes that now instead of the depth of the decoder 7 supplied signal values for the exposure time, aperture size and the identification of the automatic operation , A, are visible on the display panel 15. According to Pig. 3, the expected exposure time is displayed by lighting only the LED marked with an arrow from the LED line 16. The display thus fulfills a double function with this sequential display of depth of field and exposure values. Upon further pushing the trigger, the display is cleared again, and the shutter process is initiated, the count-up counter 9 is depleted by a pulse train of the sequence control circuit 1 and thus the exposure by means of the magnet;

The invention is not limited to the embodiment described above and of the nature of the automatic exposure of the camera of course independent

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pending · Instead of a distance scale, the visibility of which depends on the scene brightness, could also be inserted into the viewfinder frame, illuminated by an internal light source scale application · It is also possible in the interest of even more accurate depth of field display, the accuracy of the computing circuit 4 and exploit the expand digital numeric display of FIG. 2 to two decimal places. The switchable computing circuit 4 could also be formed by one computer each for the front and rear depth of field boundary. "

Claims (1)

invention claim 1 "display system for photographic cameras with automatic exposure and sharpness information in the finder, characterized in that an electronic calculation circuit, which is preferably formed by a computer switchable to two computer programs for the front and rear depth of field boundary computer, is applied, the inputs of which with signal generators for the set distance, the preselected or expected aperture size and the focal length of the lens are connected and that at the output of the arithmetic circuit fitting, the boundaries of the respective depth of field characterizing signal values one for the display of the depth of field ebereiches and the Aufnähmeentfernung one hand, and the exposure values on the other hand common , sequentially controllable display can be fed. 2, display system according to item 1, characterized in that a provided on the lens, the focal length characterizing coding as well as with the adjusting rings for distance and aperture coupled Stell · »members are designed as input signal generator for the arithmetic circuit» 3 · Display system according to item 1, characterized in that, when the input signal quantities are changed, the arithmetic circuit is automatically reset for the purpose of restarting the computer programs * Display system according to item 1, characterized in that holding circuits (5, 6) connected to this decoder (7) in the outputs of the arithmetic circuit 21775 the signal quantities corresponding to the front and rear sharpness limits are arranged » Display system according to item 1, characterized in that the holding circuit for the front boundary of the depth of field range is fed back to the sequence control circuit for the purpose of switching over the arithmetic circuit to the calculation program for the rear limit * Display system according to item 1, characterized in that the display is formed by a numerical display field (15) switchable between depth of field * and exposure display «, Display system according to item 1, characterized in that the display is constituted by an LED line (16) associated with both a scale (19) for distances and a scale (20) for exposure values and corresponding to the respective type of display are controllable · 8 »Display system according to item 1, characterized in that the calculation circuit is put into operation via a depth of field key (2) or the setting of a depth-of-field exposure program« For this JL pages drawings