Method and device for determining the depth of field of a lens system for a distance measured by measuring optics

Abstract

A method for determining the depth of field for a specific distance by means of measuring optics comprises manual optical focussing of the measuring optics by means of the human eye without projection onto a focussing screen or intermediate projection surface, monitoring of the movement of the measuring optics mechanism during focussing, determining and indicating the adjusted distance from the movement, wherein, with consideration of focal distance, aperture, hyperfocal distance and circle of confusion, the range of the depth of field to the adjusted distance is arithmetically determined and indicated.

Claims

1. Device for determining the depth of field for a specific distance, comprising manually focusable measuring optics with no focussing screen, a computer, an output unit and a sensor, wherein the measuring optics comprises a manually displaceable mechanism configured for manual focussing by an operator by means of the human eye, wherein the sensor is configured to monitor the movement of the displaceable mechanism during manual focussing of the measuring optics by the operator from an unfocused condition to a focused condition, and wherein the computer is arranged to determine the distance by evaluation of signals of the sensor from the monitored movement of the displaceable mechanism so that, under consideration of focal distance, aperture, hyperfocal distance and circle of confusion, the computer arithmetically determines and outputs the range of the depth of field to the distance.

2. Device as claimed in claim 1, wherein the measuring optics comprises a monocular lens.

3. Device as claimed in claim 2, wherein a display for indicating the distance and depth of field is provided.

4. Device as claimed in claim 3, wherein the manually displaceable mechanism of the measuring optics comprises a rotatable mechanism and wherein the sensor is engaged with the rotatable mechanism of the measuring optics via a friction wheel.

5. Device as claimed in claim 1, wherein the manually displaceable mechanism of the measuring optics comprises a rotatable mechanism and wherein the sensor is engaged with the rotatable mechanism of the measuring optics via a friction wheel.

6. Device as claimed in claim 1, wherein the sensor operates inductively.

7. A system for determining the depth of field for a specific distance, said system comprising the device of claim 1 and further including recording optics, wherein the device is electronically connected to the recording optics for data exchange, and wherein the device is configured to receive the adjusted focal distance and the adjusted focussing from the recording optics, wherein the computer of the device is configured to effect matching with the evaluation of the signals of the sensor from the monitored displaceable mechanism.

8. The system as claimed in claim 7, wherein the device comprises direction indictors for a displacement direction of the measuring optics by reason of the matching.

9. The system as claimed in claim 8, wherein the direction indicators comprise LEDs.

10. The system as claimed in claim 7, wherein the recording optics comprise a camera.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic perspective and partially transparent view of a device for determining the depth of field for a specific distance and

(2) FIG. 2 is a plan view of the device of FIG. 1 on the side remote from FIG. 1 and

(3) FIG. 3 is a flow diagram of the process of using the device of FIG. 1 for determining the depth of field for a specific distance.

(4) The figures show a device designated as a whole by 1 for determining the depth of field for a specific distance.

(5) The device includes an elongate housing 2 which forms a rod-like handle part 3 and an optics part 4. In the handle part 3 there are provided a computer (not visible), a display 5, operating elements 6, a battery compartment 7 for power supply, electrical and electronic interfaces 8 for the stationary power supply and/or electronic attachment to a camera and a memory card slot 9 for a memory card.

(6) The optics part 4 essentially contains the measuring optics 10 with the protruding eye cup 11 on one side and the focussing ring 12 on the other side. A Kepler monocular is used as the optics.

(7) In the region of the transition between the optics part 4 and handle part 3 a sensor 13 is disposed which is connected via a friction wheel 14 to the rotatable mechanism (worm-gear) of the measuring optics 10. The sensor is an inductive rotary sensor and, in a contact-free manner, senses the movement of the mechanism of the measuring optics.

(8) The display 5 serves to indicate the distance and depth of field.

(9) In addition, direction indicators 15 in the form of LEDs are provided to display the displacement direction of the optics during readjustment. These are employed when the device is used as an arrangement with an electronically attached camera (cf. below).

(10) Not only is a single depth of field determined and displayed but the determination and display of the range of the depth of field are effected for a plurality of aperture values 5, 6, 8, 11 and 16 on the display 5. Therefore the photographer is provided with a reference point for the aperture selection.

(11) In addition, an actuating button 16 is used to effect switching on and off.

(12) The device functions or is used alone in the following manner:

(13) Firstly the optics 10 are manually focussed by eye at the focussing ring 12. This sharpness is the adjusted sharpness or distance. This adjustment is detected by the sensor 13 and subsequently the distance is ascertained in a tabular manner by the computer and the depth of field is calculated accordingly.

(14) The device functions or is used in the following manner (cf. FIG. 3) when it is coupled to a camera (e.g. by a USB cable via the interface 8).

(15) First the optics 10 are manually focussed by eye at the focussing ring 12. This sharpness is the adjusted sharpness or distance. This adjustment is detected by the sensor 13 and then the distance is ascertained in a tabular manner by the computer (analogously to the case above). This adjustment is compared to the sharpness or distance adjusted at the camera, for which purpose a data exchange or matching takes place via the interface 8. (Step 1)

(16) Subsequently a check is made whether the adjusted sharpness or the thus selected distance is correct or matches that of the camera (Step 2).

(17) This will not usually be the case.

(18) By flashing of the LEDs 15 the necessary displacement direction for the readjustment of the measuring optics is displayed (Step 3), i.e. when the focussing ring 12 must be rotated counter-clockwise for readjustment purposes, the left LED flashes, in the converse case, the right LED flashes for the other displacement direction of the focussing ring 12. With the aid of the LEDs 15 the focussing ring 12 is used to readjust the sharpness or distance until the adjusted distance or the corrected sharpness corresponding to the camera is set (Step 4).

(19) If the device ascertains the adjustment of the correct sharpness or distance, both LEDs light up continuously (Step 5).

(20) This adjustment is the corrected or readjusted sharpness or distance. This is used by the computer to arithmetically determine the depth of field, wherein focal distance, aperture, hyperfocal distance and circles of confusion are considered, which issue from the camera as a result of the data exchange.

(21) The calculated values (Step 6) are output on the display 5, wherein near and far points of the sharpness for a plurality of apertures (cf. above) are indicated.

(22) Therefore the device only outputs the values which are valid for the camera.