Ryan McAvoy said:
^ ESB. Matte painting done later of the same base (The 80s equivalant of CGI). Looks 1000 times less convincing, which is why Adywan has reshot this one.
It did however look much more convincing in the original ESB. The reason why it look so fake in the SE is because the shot contains a wipe that was redone in order to avoid the generation loss and grain build up seen in the original film - stuff that did make wonders for matte paintings such as this.
In addition the shot was brightened, making it even less convincing. And lastly in 2004 it was further degrained. You were never supposed to see it that clear. Many other shots have this same problem in the SE. It's what happens when you're dickin' around with classics.