1. An image capturing apparatus comprising: an image capturing section; a designating section which designates an image area to be tracked that is included in an image captured by the image capturing section; an imaging control section which controls the image capturing section to sequentially capture images; a storing section which stores feature quantities of the image area designated by the designating section; a search point setting section which sets a plurality of search points in the image area; an updating section which updates coordinates of the search points set by the search point setting section using random numbers; a weight setting section which compares the feature quantities stored by the storing section with feature quantities of the search points updated by the updating section, and sets a weight to each search point based on similarity; a sorting section which sorts the search points that have been set a weight by the weight setting section according to the weight; a variance acquiring section which acquires a variance of the search points sorted by the sorting section; a judging section which judges a trend of changes between the images sequentially captured by the imaging control section based on changes of the variance acquired by the variance acquiring section; and an angle-of-view adjusting section which adjusts a photographing angle-of-view that includes the image area corresponding to the trend of changes judged by the judging section.