Abstract: An observation device, comprising an image sensor that forms images of a specimen and outputs an image signal, an AF detection circuit that calculates evaluation values based on the image signal, and a focus control circuit that controls focus position based on the evaluation values, wherein the AF detection circuit calculates a plurality of evaluation values based on signals relating to a plurality of frequency bands of the image signal, and the focus control circuit controls focus position based on maximum value or minimum value of the plurality of evaluation values.

Abstract: An observation device, comprising an AF detection circuit that calculates an evaluation value showing a larger value as degree of focus increases, based on an image signal, and a controller that detects focus position where focus is achieved based on the evaluation value, wherein the controller, when peaks of the evaluation value have been detected for different focus positions, detects a minimum of the evaluation value between focus positions of the plurality of peaks, and in the event that a first difference between a first peak, among the plurality of peaks, and a focus position of the minimum, and a second difference between the minimum and a focus position of a second peak, among the plurality of peaks, are within respective specified ranges, detects a focus position where focus is achieved based on the focus position of the minimum.

Abstract: An imaging apparatus includes an imaging unit and a control unit. The imaging unit accumulates electric charges synchronously with an imaging control signal to generate an imaging signal. The control unit has a first communication mode and a second communication mode. The first communication mode communicates to acquire data of a lens unit and to send an instruction to the lens unit synchronously with the imaging control signal. The second communication mode communicates to acquire data of the lens unit and to send the instruction to the lens unit at any timing asynchronous with the imaging control signal. The control unit performs focus adjustment on the basis of the data received from the lens unit and the imaging signal. The control unit switches between the first communication mode and the second communication mode in response to a state of the focus adjustment.

Abstract: An observation device, comprising an AF detection circuit that calculates an evaluation value showing a larger value as degree of focus increases, based on an image signal, and a controller that detects focus position where focus is achieved based on the evaluation value, wherein the controller, when peaks of the evaluation value have been detected for different focus positions, detects a minimum of the evaluation value between focus positions of the plurality of peaks, and in the event that a first difference between a first peak, among the plurality of peaks, and a focus position of the minimum, and a second difference between the minimum and a focus position of a second peak, among the plurality of peaks, are within respective specified ranges, detects a focus position where focus is achieved based on the focus position of the minimum.

Abstract: An observation device, comprising an image sensor that forms images of a specimen and outputs an image signal, an AF detection circuit that calculates evaluation values based on the image signal, and a focus control circuit that controls focus position based on the evaluation values, wherein the AF detection circuit calculates a plurality of evaluation values based on signals relating to a plurality of frequency bands of the image signal, and the focus control circuit controls focus position based on maximum value or minimum value of the plurality of evaluation values.

Abstract: While a focus lens is moving to a focus lens driving target position, a controller of a focus adjustment device switches a moving speed of the focus lens from a first speed to a second speed. In particular, the controller calculates the number of times the defocus amount can be calculated when the focus lens moves at a predetermined speed in a section between a first position in which the moving speed is switched and a second position in which the focus lens starts being controlled to stop in the focus lens driving target position, and calculates the second speed based on the number of times, the first position and the focus lens driving target position.

Abstract: An imaging apparatus includes an imaging unit and a control unit. The imaging unit accumulates electric charges synchronously with an imaging control signal to generate an imaging signal. The control unit has a first communication mode and a second communication mode. The first communication mode communicates to acquire data of a lens unit and to send an instruction to the lens unit synchronously with the imaging control signal. The second communication mode communicates to acquire data of the lens unit and to send the instruction to the lens unit at any timing asynchronous with the imaging control signal. The control unit performs focus adjustment on the basis of the data received from the lens unit and the imaging signal. The control unit switches between the first communication mode and the second communication mode in response to a state of the focus adjustment.

Abstract: An imaging apparatus, comprising a focus detection section that detects an out of focus amount and an out of focus direction by carrying out a focus detection operation using phase difference detection based on a pixel signal of focus detection pixels that has been thinned and read out, a swirl error determination section that determines swirl error arising in accordance with inclination of an optical image with respect to a direction that is orthogonal to a phase difference detection direction, based on the pixel signal of the focus detection pixels that has been thinned and read out, and an AF control section that determines whether or not to carry out AF operation adopting output of the focus detection section, based on output of the swirl error determination section.

Abstract: While a focus lens is moving to a focus lens driving target position, a controller of a focus adjustment device switches a moving speed of the focus lens from a first speed to a second speed. In particular, the controller calculates the number of times the defocus amount can be calculated when the focus lens moves at a predetermined speed in a section between a first position in which the moving speed is switched and a second position in which the focus lens starts being controlled to stop in the focus lens driving target position, and calculates the second speed based on the number of times, the first position and the focus lens driving target position.

Abstract: An imaging apparatus, comprising a focus detection section that detects an out of focus amount and an out of focus direction by carrying out a focus detection operation using phase difference detection based on a pixel signal of focus detection pixels that has been thinned and read out, a swirl error determination section that determines swirl error arising in accordance with inclination of an optical image with respect to a direction that is orthogonal to a phase difference detection direction, based on the pixel signal of the focus detection pixels that has been thinned and read out, and an AF control section that determines whether or not to carry out AF operation adopting output of the focus detection section, based on output of the swirl error determination section.