So, the bottom line is that you don't know how they did it, correct? I don't know either; welcome to the club!
No, that's not the bottom line at all. Lack of absolute certainty is not remotely the same as total ignorance. I've explained to you what the most likely possibilities are, based on general knowledge of the subject matter, observation of the data, and deductive reasoning. Or rather, I've explained what I'm reasonably certain the explanation is, but since I think intellectual honesty demands openness to alternatives, I've offered a second possibility as well, though I don't consider it as probable. I think if the "auras" cel were far enough above the other cels to be out of focus, it would also be far enough away that the difference in image size would be much more pronounced.
One cannot be intellectually responsible -- or honest with oneself or others -- if one does not admit the possibility that one's conclusions could be wrong. But that is not the same thing as knowing nothing. Honest doubt is not ignorance; it is simply willingness to question and learn.