It's a really interesting scene to me, because it shows just how much a small change can affect everything in an adaptation.
The book goes to considerable effort to motivate why Duke Leto doesn't turn on his shield at this moment—it may even be the original reason for the idea that shields and lasguns cause nuclear-like "explosive pyrotechnics" if they interact.
The movie, on the other hand, makes no reference to this phenomenon or danger, and instead simply introduces the concept of missiles with drills that can penetrate shields. Which means it can allow Leto to turn on his shield in this scene, as seen in the screencap. The fallout of this adaptation choice is that shields are relatively nerfed in the movie version, with significant implications for how all the battle and combat scenes are staged, the design of armor, etc.
