Patent ID: 6859620

Claim:
A rangefinder apparatus comprising: autofocus (AF) data generating means for forming an image of light from an object to be subjected to rangefinding onto a pair of line sensors, each line sensor including a plurality of light-detecting elements, and generating AF data for computing a correlation value according to signals obtained from the light-detecting elements; AF data acquiring means for acquiring the AF data from a pair of employed sensor areas used for rangefinding in the pair of line sensors; correlation value computing means for determining a pair of window areas for selecting the AF data to be used for computing a correlation value within the pair of employed sensor areas, and successively computing correlation values while shifting the pair of window areas; object distance calculating means for detecting a shift amount of the window areas yielding highest correlation according to the correlation values computed by the correlation value computing means and calculating distance to the object according to the shift amount yielding the highest correlation; and rangefinding incapability determining means for calculating an index value indicative of a degree of oscillation of the AF data in predetermined areas of the pair of line sensors, and determining that the rangefinder apparatus in incapable of rangefinding when the index value is larger than a reference value.