Star Wars Question

For Chirstmas I recieved the box set of the first Star Wars Trilogy. While I have seen all many times, I sometimes see things that don't make sense that I have not noticed before.

For instance, in "A New Hope", the first Star Wars movie, towards the end of the movie when Luke is in his X-wing fighter in the trench preparing to destroy the Death Star, Darth Vader is hot on his tail. Luke, with no Jedi training, turns off his targeting computer and uses the Force to fire his torpedos. Meanwhile, Vader, a powerful trained Jedi master of the dark side of the Force, has to rely on the targeting computer in his fighter to fire on Luke and others.

That doesn't make much sense to me. Was it a laps in story continuity or purposeful by Lucas?

I believe it was sloppy writing/direction. I still like the movie though and will continue to watch it many more times.

This is One Man's Opinion