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.

The control method includes determining whether a plurality of pupils can be included in a specific depth in a case where pupil information about the plurality of pupils of a same subject is acquired, and in a case where it is determined in the determining that the plurality of pupils of the same subject cannot be included in the specific depth, control is performed so that different indexes are displayed on a pupil within the specific depth and a pupil outside the specific depth.

Automatic focus-adjusting glasses includes an imager configured to be capable of acquiring image information; a variable focus lens configured to be capable of changing a focal length; a depth-information acquiring unit configured to acquire depth information of each position of the image information acquired by the imager; an attention-position determining unit configured to determine an attention position in the image information acquired by the imager; a depth-information identifying unit configured to identify a depth of the attention position based on the attention position in the image information determined by the attention-position determining unit and the depth information; and a focal-length controller configured to set a focal length of the variable focus lens based on the depth of the attention position.

Automatic focus-adjusting glasses includes an imager configured to be capable of acquiring image information; a variable focus lens configured to be capable of changing a focal length; a depth-information acquiring unit configured to acquire depth information of each position of the image information acquired by the imager; an attention-position determining unit configured to determine an attention position in the image information acquired by the imager; a depth-information identifying unit configured to identify a depth of the attention position based on the attention position in the image information determined by the attention-position determining unit and the depth information; and a focal-length controller configured to set a focal length of the variable focus lens based on the depth of the attention position.