The invention provides a stabilizing system for an image-producing means (8) operated on a non-stable platform (18), the system including a yaw axis (2) attachable at one of its ends to the platform (18); an angularly bent arm (26) comprising two limbs, to the first of which limbs the other end of the yaw axis (2) is fixedly attached; a front roll axis (6') mounted on, or integral with, the first limb; lateral structures (24,24') rigidly linked by a connecting member (25) and at least indirectly supported by the bent arm (26), between which lateral structures (24,24') the image-producing means (8) can freely perform a pitching movement; at least one pitch axis (4) supported by at least one of the lateral structures (24,24'); a rear roll axis (6) fixedly attached to the connecting member (25) and freely passing through the end portion of the second one of the limbs of the bent arm (26), the front roll axis (6') and the rear roll axis (6) being parallel, the front roll axis (6') being positioned at a point above the lateral structures (24,24'); a cross member (30) pivotably mounted on the front roll axis (6'), and at least one upright (28,28') at each end of the cross member (30), one end of the upright (28,28') being pivotably mounted on the cross member (30) and its other end being articulated to one of the lateral structures (24,24'); wherein the cross member (30) and the uprights (28,28') define a portal facilitating the unobscured passage of light.