Focal point adjusting method and focal point adjusting device in imaging apparatus

Abstract

This invention provides a focal point regulating method and focal point regulating device in a camera device. In the camera, when a camera lens is moved at am optical axis direction to regulate a focusing position, the focusing position can be easily regulated with high precision even if the peak points of the picked contrast feature and MTF feature are unclear. A first and second test charts (CH1, CH2) each having an imaging pattern defined by white color and black color are set in front and rear of the target position (P) of an object, a focus lens (3) is moved in the direction of optical axis X, focal point evaluation value of the imaging pattern focused on an image element (5) is determined for each of the first and second test charts (CH1, CH2) in correspondence with the movement quantity of the focus lens (3), and the position of the focus lens (3) is set such that the focal point evaluation value in the first test chart (CH1) coincides with the focal point evaluation value in the second test chart (CH2).

Description

technical field [0001] The present invention relates to a focus adjustment method and a focus adjustment device for setting an imaging lens at an in-focus position using image signals obtained by an imaging element such as a CCD in an imaging device. Background technique [0002] In the past, such as Figure 6 As shown in (a), there is a known focus adjustment method using the mountain-climbing method (mountain-climbing method). In an imaging device 201 such as a camera, the contrast of the projected light of the imaged image is detected, and the focus adjustment is performed by moving the imaging optical system so that the light The contrast becomes maximum. [0003] The imaging device 201 is configured to guide an image of a subject 203 through an imaging lens 202 to an imaging element 204 such as a CCD, convert it into an electrical signal, and detect contrast in a focus detection unit 205 . [0004] Such as Figure 6 As shown in (b), the focus adjustment method of the m...

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Problems solved by technology

[0008] However, according to the focus adjustment method of obtaining the maximum value of contrast and the maximum value of MTF as in the conventional mountain climbing method, it is generally necessary to move the camera lens back and forth to both sides through the focus position in the direction of the optical axis to detect the position where the contrast is optimal. , so operability may be impaired for focus adjustment (that is, operability may be impaired compared with the method of adjusting the camera lens in one direction)

Also, when the contrast characteristics and MTF characteristics with respect to the amount of defocus are close to flat near the peak point and the peak point cannot be clearly indicated, it may not be easy to adjust the focus position of the imaging lens with high precision.

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