Back to the shot of the TIEs, I found this quote in American Cinematographer:

"For example, in the shot of Darth Vader's ship flanked by two TIE fighters flying through a Death Star trench, George wanted us to make the villain's vessels larger and more dominant. We found the TIE fighter elements and Darth Vader's ship, but even after I found all of the other Death Star trench backgrounds for the space battle, I couldn't find that particular trench plate. Then I realized that on certain shots they had used the same take over and over again—but in different segments, to make viewers think it was a different background. Since the backgrounds were blurred, it sometimes drove us nuts, because we'd find ourselves saying, late at night 'There's a triangle going by, there's a square. Okay, if a circle follows that, then that's the right one!' A lot of times things worked in reverse, which just made things that much harder to piece together."

This shot was re-composited using the original elements? That's pretty impressive. So much was done to this movie besides the CGI, but that's most behind the scenes things focus on. These AC articles talk about matching starfields and finding elements that suggest that there's even more done to this movie than we know. If this "zoomed in" shot can be lined up perfectly, I'm wondering how much was recreated flawlessly?