Abstract: Picture display device comprising a display tube with an electron gun having a tubular structure with an outer surface and an inner surface on which a helical resistance structure of a material having a high electrical resistance constituting a focusing lens is provided. The outer surface is provided with an electrode of readily electrically conducting material arranged opposite at least a part of the focusing lens for capacitively controlling the focusing lens by means of a dynamically variable voltage the amplitude of which is a function of the position of the electron beam spot on the display screen.