US-12621568-B2 - Focusing control device, imaging apparatus, focusing control method, and focusing control program

US12621568B2US 12621568 B2US12621568 B2US 12621568B2US-12621568-B2

Abstract

There is provided a focusing control device that performs focusing control in each frame period of imaging, the focusing control device comprising: a processor, in which the processor is configured to: predict, in an N-th frame period, a lens driving time for moving a focus lens to a first target focusing position in an (N+1)-th frame period based on first time-series AF information in which AF information obtained in an (N−1)-th frame period is included; and select a driving method of the focus lens that is to be executed in the N-th frame period based on the predicted lens driving time.

Inventors

Hideaki KOKUBUN
Hitoshi SAKURABU

Assignees

FUJIFILM CORPORATION

Dates

Publication Date: 20260505
Application Date: 20240902
Priority Date: 20230908

Claims (15)

1 . A focusing control device that performs focusing control in each frame period of imaging, the focusing control device comprising: a processor, wherein the processor is configured to: predict, in an N-th frame period, a lens driving time for moving a focus lens to a first target focusing position in an (N+1)-th frame period based on first time-series auto focus (AF) information in which AF information obtained in an (N−1)-th frame period is included; and select a driving method of the focus lens that is to be executed in the N-th frame period based on the predicted lens driving time, wherein the processor is configured to, in a case where the lens driving time is longer than a threshold value, select, as the driving method, a first driving method of starting driving of the focus lens toward the first target focusing position before acquiring the AF information in the N-th frame period.
2 . The focusing control device according to claim 1 , wherein the processor is configured to, in a case where the lens driving time is longer than a threshold value, select, as the driving method, a first driving method of starting driving of the focus lens toward the first target focusing position at a timing at which the focusing control in the (N+1)-th frame period is in time.
3 . The focusing control device according to claim 2 , wherein the processor is configured to, in a case where the lens driving time to the first target focusing position is equal to or shorter than the threshold value, select, as the driving method, a second driving method of predicting a second target focusing position in the (N+1)-th frame period based on second time-series AF information in which the AF information in the N-th frame period is included, and starting driving of the focus lens toward the predicted second target focusing position.
4 . The focusing control device according to claim 1 , wherein the processor is configured to, in a case where the lens driving time to the first target focusing position is equal to or shorter than a threshold value, select, as the driving method, a second driving method of predicting a second target focusing position in the (N+1)-th frame period based on second time-series AF information in which the AF information in the N-th frame period is included, and starting driving of the focus lens toward the predicted second target focusing position.
5 . The focusing control device according to claim 4 , wherein the processor is configured to, in a case where an AF area for acquiring the AF information is set in the imaging region: acquire information related to reading of an image that includes the imaging region and is obtained by the imaging element; determine a state of the reading of the image corresponding to the AF area based on the information; and start prediction of the second target focusing position in a case where it is determined that the reading of the image corresponding to the AF area is completed.
6 . The focusing control device according to claim 1 , wherein the AF information is information acquired by using phase difference detection pixels disposed in an imaging region of an imaging element.
7 . The focusing control device according to claim 1 , wherein the AF information used in the first time-series AF information is acquired based on a main image captured once in each of the frame periods.
8 . The focusing control device according to claim 1 , wherein the AF information used in the first time-series AF information is acquired based on a live view image captured in each of the frame periods.
9 . The focusing control device according to claim 8 , wherein the live view image is a latest live view image among a plurality of live view images captured in each of the frame periods.
10 . The focusing control device according to claim 1 , wherein the focusing control is performed during continuous imaging in which a main image is continuously captured over a plurality of frame periods while a release button is being pushed.
11 . The focusing control device according to claim 1 , wherein, as a stop control method of stopping the focus lens during movement, two stop control methods of a first stop control method and a second stop control method are provided for the focusing control device, the first stop control method being a method of decelerating the focus lens to a preset speed and then stopping the focus lens by using a constant speed section in which the focus lens is moved at a constant speed, the second stop control method being a method of continuously decelerating the focus lens and stopping the focus lens without using the constant speed section.
12 . The focusing control device according to claim 11 , wherein, as continuous imaging modes, two continuous imaging modes of a continuous-imaging-interval priority mode in which a continuous imaging interval is kept constant and a focus priority mode in which accuracy of focusing is prioritized over the continuous imaging interval are provided, and the processor is configured to select the first stop control method in a case where the focus priority mode is selected as the continuous imaging mode and an F number of an optical system including the focus lens is equal to or smaller than a setting value which is preset.
13 . An imaging apparatus comprising: the focusing control device according to claim 1 an imaging element.
14 . A focusing control method of performing focusing control in each frame period of imaging, the focusing control method comprising: predicting, in an N-th frame period, a lens driving time for moving a focus lens to a first target focusing position in an (N+1)-th frame period based on first time-series auto focus (AF) information in which AF information obtained in an (N−1)-th frame period is included; selecting a driving method of the focus lens that is to be executed in the N-th frame period based on the predicted lens driving time; and in a case where the lens driving time is longer than a threshold value, selecting, as the driving method, a first driving method of starting driving of the focus lens toward the first target focusing position before acquiring the AF information in the N-th frame period.
15 . A non-transitory computer-readable storage medium storing a focusing control program causing a processor to execute focusing control in each frame period of imaging, the focusing control program causing the processor to execute a process comprising: predicting, in an N-th frame period, a lens driving time for moving a focus lens to a first target focusing position in an (N+1)-th frame period based on first time-series auto focus (AF) information in which AF information obtained in an (N−1)-th frame period is included; selecting a driving method of the focus lens that is to be executed in the N-th frame period based on the predicted lens driving time; and in a case where the lens driving time is longer than a threshold value, selecting, as the driving method, a first driving method of starting driving of the focus lens toward the first target focusing position before acquiring the AF information in the N-th frame period.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2023-146379 filed on Sep. 8, 2023. The above application is hereby expressly incorporated by reference, in its entirety, into the present application. BACKGROUND 1. Technical Field The technology of the present disclosure relates to a focusing control device, an imaging apparatus, a focusing control method, and a focusing control program. 2. Description of the Related Art JP7171966B discloses an imaging apparatus that performs continuous imaging by moving a focus lens while avoiding a period of main exposure by an imaging sensor according to an instruction of a processor and continuously performing the main exposure at a predetermined time interval by the imaging sensor, in which the processor is configured to calculate a first focusing position of the focus lens with respect to a specific subject based on image data obtained by imaging the specific subject with the main exposure by the imaging sensor in a specific frame in which the main exposure is performed in a continuous imaging period, predict a second focusing position of the focus lens with respect to the specific subject in a frame which is a plurality of frames later than the specific frame with reference to the first focusing position in the continuous imaging period, and move the focus lens toward the second focusing position. JP2018-037959A discloses an imaging apparatus comprising an imaging element including a focus detection pixel, a focus detection unit that performs focus detection of an imaging optical system based on a focus detection signal accumulated by the focus detection pixel, a continuous imaging unit that causes the imaging element to execute accumulation of a recording image signal a plurality of times, a storage unit that stores the recording image signal, a prediction unit that predicts a focusing position of a subject when acquiring the recording image signal based on a result of the focus detection by the focus detection unit and information related to an accumulation timing of the focus detection signal used for the focus detection, and a focus adjustment unit that adjusts a focus of the imaging optical system based on a prediction result by the prediction unit, in which the imaging element accumulates the focus detection signal in a period in which the storage unit cannot store the recording image signal, and the focus detection unit performs the focus detection using the focus detection signal acquired in the period. SUMMARY One embodiment according to the technology of the present disclosure provides a focusing control device, an imaging apparatus, a focusing control method, and a focusing control program capable of performing appropriate focusing according to a change in a movement of a subject or a movement of an imaging apparatus. In order to achieve the above object, according to the present disclosure, there is provided a focusing control device that performs focusing control in each frame period of imaging, the focusing control device comprising: a processor, in which the processor is configured to: predict, in an N-th frame period, a lens driving time for moving a focus lens to a first target focusing position in an (N+1)-th frame period based on first time-series AF information in which AF information obtained in an (N−1)-th frame period is included; and select a driving method of the focus lens that is to be executed in the N-th frame period based on the predicted lens driving time. Preferably, the processor is configured to, in a case where the lens driving time is longer than a threshold value, select, as the driving method, a first driving method of starting driving of the focus lens toward the first target focusing position at a timing at which the focusing control in the (N+1)-th frame period is in time. Preferably, the processor is configured to, in a case where the lens driving time is longer than a threshold value, select, as the driving method, a first driving method of starting driving of the focus lens toward the first target focusing position before acquiring the AF information in the N-th frame period. Preferably, the processor is configured to, in a case where the lens driving time to the first target focusing position is equal to or shorter than a threshold value, select, as the driving method, a second driving method of predicting a second target focusing position in the (N+1)-th frame period based on second time-series AF information in which the AF information in the N-th frame period is included, and starting driving of the focus lens toward the predicted second target focusing position. Preferably, the processor is configured to, in a case where the lens driving time to the first target focusing position is equal to or shorter than a threshold value, select, as the driving method, a second driving method of predicting a second target focusing position in the