Or...for a different perspective - take a look at TMP!
Here, we have the scene were the Enterprise was being attacked by V'Ger for the first time. We see Chekov's station and the shield display clearly shows a "bubble" while the system is energized.
Then, some time later, after Chekov returns to his post after recovering from being zapped by the plasma probe, we see the same shield display, but now with NO bubble. The shields were now down due to the ship being inside the cloud.
I doubt many may have caught this, so i wanted to share it here!