Camera with radar-based autofocus

1. A camera comprising:

an optical system configured to record images based on light entering the optical system from an optical field of view, said optical system comprising an autofocus system configured to focus said optical system on a target in the optical field of view;

a radar system configured to obtain distance and speed information of targets within a radar field of view that overlaps with said optical field of view, said distance and speed information indicating the distance and speed of targets with respect to the camera; and

circuitry configured to

select a target within the radar field of view based on a selected distance;

derive a speed of the selected target from the distance and speed information obtained by the radar system; and

control the autofocus system to focus said optical system on a target within the optical field of view having the selected distance and the derived speed.

2. The camera as claimed in claim 1 , further comprising:

a user interface allowing a user to select a range or value of distance and/or speed to be used by the circuitry for controlling the autofocus system.

3. The camera as claimed in claim 1 , further comprising:

a user interface allowing a user to select a predetermined focusing mode according to which the circuitry automatically controls the autofocus system to focus said optical system on a target having a predetermined distance and/or speed.

4. The camera as claimed in claim 1 , wherein

said radar system is configured to have a radar field of view that substantially covers the optical field of view.

5. The camera as claimed in claim 1 , wherein said circuitry is configured to:

select a target within the radar field of view based on a selected speed;

derive the distance of the selected target from the distance and speed information obtained by the radar system; and

control the autofocus system to focus said optical system on a target within the optical field of view having the selected speed and the derived distance.

6. The camera as claimed in claim 1 , wherein

said circuitry is configured to control the autofocus system to focus said optical system on a target within the optical field of view having a speed above a selected speed threshold.

7. The camera as claimed in claim 1 , wherein

said circuitry is configured to control the autofocus system to focus said optical system on the fastest target within the optical field of view or on a target having a relative speed of substantially zero with respect to the camera.

8. The camera as claimed in claim 1 , wherein

said circuitry is configured to control the autofocus system to focus said optical system on a target within the optical field of view moving into a predetermined direction in relation to the camera.

9. The camera as claimed in claim 1 , wherein

the radar system is configured to obtain a Doppler-Range matrix of the radar field of view, said Doppler-Range matrix including the distance and speed information of the targets within the radar field of view.

10. The camera as claimed in claim 1 , wherein

the optical system is configured to automatically record an image once it is controlled by the circuitry to focus on a target based on a selected distance and/or a selected speed.

11. The camera as claimed in claim 1 , wherein

the optical system is configured to record the speed and/or distance information of the target on which the optical system is focused or of all targets within the optical field of view along with a recorded image.

12. The camera as claimed in claim 1 , wherein

the circuitry is configured to control an observation time and/or resolution of the radar system based on the distance of the targets within the radar field of view.

13. The camera as claimed in claim 1 , wherein

the radar system is an OFDM radar system.

14. The camera as claimed in claim 13 , wherein

the circuitry unit is configured to control an observation time of the radar system based on the distance of the targets within the radar field of view by adapting the length and/or number of OFDM symbols transmitted by the radar system.

15. The camera as claimed in claim 13 , wherein

the OFDM radar system is configured to embed data into the transmitted OFDM signals, wherein said data comprise identification data identifying the camera allowing the camera to identify if received radiation is received in response to radiation transmitted by its radar system or by radar systems of other cameras.

16. The camera as claimed in claim 13 , wherein

the OFDM radar system is configured to embed data into the transmitted OFDM signals, wherein said data comprise synchronization data for synchronizing two or more cameras.

17. An autofocus system for a camera comprising:

an autofocus system configured to focus an optical system of the camera provided for recording images based on light entering the optical system from an optical field of view on a target in the optical field of view; and

circuitry configured to

acquire distance and speed information of targets within a radar field of view that overlaps with said optical field of view from a radar system, said distance and speed information indicating the distance and speed of targets with respect to the camera;

select a target within the radar field of view based on the selected distance;

derive a speed of the selected target from the distance and speed information acquired from the radar system; and

control the autofocus system to focus said optical system on a target within the optical field of view having the selected distance and the derived speed.

18. An autofocus control method for a camera comprising:

receiving distance and speed information of targets within a radar field of view that overlaps with an optical field of view of an optical system of the camera provided for recording images based on light entering the optical system from an optical field of view on a target in the optical field of view, said distance and speed information being provided by a radar system of the camera provided for obtaining distance and speed information of targets within the radar field of view and indicating the distance and speed of targets with respect to the camera;

selecting a target within the radar field of view based on a selected distance;

deriving a speed of the selected target from the distance and speed information provided by the radar system; and

controlling an autofocus system of the camera to focus said optical system on a target within the optical field of view having the selected distance and the derived speed.

19. A non-transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method as claimed in claim 18 to be performed.