1. In a focus control system for automatically focusing objective lens means onto an object, the combination comprising: (A) means for receiving first and second detection images of the object and for providing image signals corresponding to the first and second detection images; (B) means for detecting, on the basis of the image signals provided by said image receiving means, the range of the object, said range detection means detecting the object range by detecting, on the basis of the image signals, the relative positional difference between corresponding image portions of the first and second detection images and providing data on the object range; (C) means operatively associated with said objective lens means for providing data on an adjusted position of the lens means along an optical axis thereof; (D) means for detecting, on the basis of the object range data provided by said range detection means and the data on the adjusted position of the lens means provided by said position data providing means, deviation of the adjusted position of the objective lens means from an in-focus position, at which the lens means is properly focused onto the object, said deviation detection means providing data on said deviation; (E) means for driving the objective lens means along an optical axis of the lens means; (F) means for controlling said driving means on the basis of the deviation data provided by said deviation detection means so as to position the objective lens means to said in-focus position, said drive control means being so arranged that it can continuously operate said driving means; and (G) means for controlling the driving speed of said driving means on the basis of the magnitude of the deviation indicated by the deviation data, said speed control means including means for comparing the magnitude of the deviation with a predetermined threshold, and being arranged to cause said driving means to drive the lens means toward the in-focus position at a speed which is determined by the result of the comparison performed by said comparing means according to a function which provides a stepwise change between two different speed levels, said speed control means further including means for selecting the threshold.