AUTOMATIC FOCUSING DEVICE

摘要

PURPOSE:To attain high speed automatic focusing by providing a means for setting the correction coefficient of the magnification of a variable power lens and a means for correcting the error of focusing quantity. CONSTITUTION:The titled device provides a 1st correction coefficient setting means 80 for setting the correction coefficient of the magnification of the vari able power lens group 4 and a coefficient setting means 100 for correcting the effect on the moving quantity of the error of the magnification of the vari able power lens group 4 and the error of the defocusing quantity caused by errors in production in a dimension for prescribing the relation between the positions of a photodetector group and a fine lens group in a focus detection means. With such a constitution, a focusing controller 78 incorporates the set outputs from the 1st and the 2nd means 80 and 100 and executes correction arithmetic processing so as to calculate the moving quantity of a focus lens group. Namely, it is assumed that the correction coefficient alpha is specific within the range of 0.90<=alpha<=1.10. Thus, automatic focusing can be executed at high speed even when the error of the magnification of the variable power lens group and the error of the focusing quantity are large.