Hm, I compared the size to that building in the background. To me it seemed to vary compared to that and I don't know if it is supposed to. But I must admit I didn't spend much time watching the video that closely and I never saw it working in reality either. It just surprised me, to see it working like that.

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.

it's exactly like a sniper scope with the red dot in the middle, if you have ever used one. I have and that's what the red dot does, when I look in to the scope from a distance it looks larger than it really is. The lense in the scope causes it to look as if it is getting larger when it really isnt.

Yep I am a rifle shooter as well :) The principals are totally different. In a rifle scope the image of the sighting reference be it a dot or cross hair is magnified, therefore there is an associated focal length. In these sights the aiming refrence and your eye are seperated by a lens. Therfore any time you change the distance between your eye and the scope the amount of magnification changes as does the aiming refrence (dot or cross hair) size.

With a reflector sight there is no magnification whatsoever on the displayed reticle. There is no lens between your eye and the projected reticle. The reticle is displayed at infinity. I have used slightly more advanced gyro reflector sights in real life ... Ferranti Isis and CSF97K and HUDs,though more modern than the Revis the basic principals are the same. The symbology size does not change as you move your eyes closer or further from the combining glass. If it did than any form of angular range finding (stadimetric) would not be possible.

I see from the photo's that the sight was inline with the right eye. I am assuming US and British planes had it centrally placed. Would this have made much difference?
And if it did, one hopes SOW models this...

The illusion that the sight is changing size is due to the fact that as you move toward, or away from the sight, you're also moving toward or away from the reflector glass, and the wall behind it.

You're actually having more or less surface area of the glass, and wall in your field of view at any given time. The sight stays the same size, the wall and glass change size due to retinal image size projected in the eye.

That makes sense Heloguy

Zoom lense video cameras apparently existed since the 1930s (I didn't know that)

its an old gunsight mounted in somebody's living room, recording the image with a modern camera ;)

Basically a reflector sight meant your reticle, ring and other marks remained "calibrated" regardless of head position.

This was essential because in real life you worked out range to target and hence whether the target was in convergence and how much deflection was needed using the ring and tick marks.

Of course the reflector sight is not that important for 90% of gamers because most people use icons to read off range and either shoot from the dead six or deflection shoot by guesswork, insight and "invoking the force". Then again if they can pull it off consistently good luck to them :)