[IvanK]

No Mastiff thats the point, any reflector gunsight or HUD works on the collimated principal of a projected image. Its nothing like a Sniper scope or high powered binoculars. The Reflector gunsights principal reason for invention was to present a constant sized reticle image independent of the pilots head position. the Reticle (by the process of collimation) is focused at infinity therefore its angular dimension is independent of the shooters eye position.

Unlike a Ring and bead where the Angular dimension of the Ring is directly proportional to the distance between the eye and the ring. In fact A Ring and Bead gunsight is only accurate at one fixed Eye to ring distance.... thats why there was a need for the reflector gunsight.

What I think is happening in the video clip is that the apperrance of the pilots eye getting closer to the sight is in fact the zoom of the video camera. The camera itself is moreless at a fixed distance from the sight but the zoom control gives the illusion that the eye is getting closer to the sight when in fact its not. So the Zoom magnification has in effect two differrent focal distances the sight body itself and the reticle which is (by definition) at infinity. The net result is that this camera zoom does not replicate the effect of the pilot moving his head closer to the sight.