I was just watching A New Hope, and I noticed that the plans on the computer display show the trench passing through the main dish. However the model of the death star used for the wide angle shots show the dish above the trench, with the trench not passing through it.
Is there an explanation for the difference?
Astonishingly, this discrepancy has never been explained1. No canon source addresses it, and neither has any Legends source (so far as I know). There was much fan speculation that this would finally be answered in Rogue One but, alas, it was not so.
Amusingly, the original Death Star plans, seen in Attack of the Clones, depict the focusing dish in the correct, angled position:
So it can't even be explained away by being an early design idea that was later abandoned.
It's because the animator was working based on an early Ralph McQuarrie painting of the Death Star, which depicts the dish at the equator2:
The animator, Larry Cuba, discusses the design process (and mentions this fact) in a video he produced on the subject:
1 Except the once
2 Full disclosure: I didn't actually know this. I found it out reading Pablo Hidalgo's Twitter feed, which is fascinating.
This was addressed in the The Death Star Owner's Technical Manual factbook. In short, the plans for the Death Star (the ones stolen by Leia) appear to also contain schematics from an earlier version where the dish was intended to be equatorial.
Imperial Schematic Design System Data, obtained by a rebel agent from a military communications complex on Galvoni III after the Battle of Yavin, yielded schematics for a concept "Death Star" with a superlaser cannon located on the sphere's equator.
Notably, the book contains a cleaned-up version of McQuarrie's Death Star concept art.
