Thanks for the links to Ady's previous comments re: the meditation chamber doorway ImperialFighter.

On a related note, I was re-watching the scene where Vader's helmet gets lowered onto his head while in the meditation chamber, and I started wondering: given the two piece configuration we see in ROTJ and ROTS, as well as the way it's removed/installed in each, wouldn't his face mask already be on? If so, shouldn't we be seeing the top of the mask (the raised portion that sits on top of Vader's head)? (See pictures 1 and 2 for reference). I suppose one could argue that the mask and helmet are being lowered simultaneously, however we never see them put in place/removed together at any other time.

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Also, when the helmet is lowered in ESB, there appears to be some sort of appendage on the front of the helmet -- I'm not sure if it's supposed to be the triangular vent of the front of the mask or not, but again, going by all other images of Vader's mask, I don't think we'd see any such protrusion, even if the mask were indeed attached at the time (see images 3, 4 & 5). (Note: the appendage in question is more visible in motion than in the screen cap below). That being said, I'm not sure if it's possible to digitally erase this portion or not in motion.