Imagine two minor characters in a house. One is a thief. He searches for something specific and imagines what he will do when he finds it. In another part of the house, the second character hides. She hears him break in and fears what will happen when she is discovered. Omniscient: pan out. See only how the two characters act separately. = lose the inner dialog. Since it's a break-in, neither is talking, unless it's to themselves. He moves about. She reacts. back and forth. builds suspense, but lies flat for want of inner emotion. Limited 3rd person: He sees X and imagines how it will affect his life. unaware that she is in another room. or have to pick the other. She frets that the person in the other room will discover her and dreads what the consequences will be. (but she can only hear what he is doing.) But, You can't have both?? D Can provide text, but as this is my first post, I'll let you decide.
Essentially, no, in limited but you can always head-hop without going fully omniscient. Or you can switch POVs mid chapter with the classic double space break. That happens all the time, even if only for a paragraph or two, particularly in tense, suspenseful action scenes. Tom Clancy, for example, would often do that between two airplanes/submarines/tank groups/whatever hunting each other. It's doable.
Seconding this, scene breaks (or section breaks? I always forget what the double space is called) allows you to cleanly switch between two point of views within a scene. I do recommend trying to not switch *too* frequently, because constant jumps can be jarring, even if some writers pull it off well.
Yes, you can switch, and it's best done at a scene break as @Idiosyncratic says. But I don't think you need to go into omniscient, I would do it in objective. It's a (seemingly forgotten but very popular not long ago) POV that's sort of like omniscient, only you don't need to present inner thoughts or feelings or keep switching into different characters' heads. It's also called the fly-on-the-wall perspective, because it can be anywhere, even in a sealed tomb, and there doesn't need to be an eyewitness character (as there does in limited). It's motivated by what the reader needs to know. 40 or 50 years ago it was extremely common, possibly the most popular POV for detectiver stories and mysteries—for instance a scene where you want the readers to witness something no character could see. I've been able to find precious little about objective on the internet—knowledge of it seems to have disappeared into the vaults of history. But I think it's extremely good to know about and deserves to be resurrected. It actually does get used a lot (because it's kind of hard to write without it in certain situations), but people mistakenly call it omniscient. It's sort of like one aspect of omniscient, but without the difficult parts (the all-knowing narration and the need to keep switching POV constantly). Give me a minute, I'll see if I can link to the handful of articles I've managed to find about it.
Objective POV links: Point of view: Complete guide to POV in stories —Scroll down to the section called Objective point of view vs involved Point of View – First Person, Third Person, or Objective? —Bottom section of the article Objective Point Of View @ FictionWriters' Mentor Should I write in Third Person Objective? @ Editor's Quill Examples: Hills Like White Elephants by Hemingway (pdf)—a commonly-cited example of a story written entirely in objective The Maltese Falcon by Dashiell Hammet @ Amazon link should open the Read Inside. Give it a few seconds Well this is heartening—it looks like there are more articles about it than last time I checked. I compiled some good info about using it, in particular how to transition into or out of different POVs, which can be done within a scene (with or without a scene break) if you understand how to do it: Switching between close and distant 3rd Make sure to read the comments (click on the Sort Comments widget at the beginning of the comments section and select Oldest to Newest, otherwise they'll be in reverse order). What I was calling Distant 3rd is actually objective, though the technique of transitioning will work between any 2 POV techniques. Here's a post I did about transitioning between the pov's of 2 different characters, where I examined how it was handled in a short story: Next-Door Neighbor, by Don D'Ammassa
[QUOTE="O Omniscient: pan out. See only how the two characters act separately. = lose the inner dialog. Since it's a break-in, neither is talking, unless it's to themselves. He moves about. She reacts. back and forth. builds suspense, but lies flat for want of inner emotion. Limited 3rd person: He sees X and imagines how it will affect his life. unaware that she is in another room. [/QUOTE] This is actually a common form of viewpoint management, called limited omniscience. Some sources call pure limited viewpoint limited omniscience, but they are just confusing people. In real limited omniscience, there is a narrative omniscient person who oversees the work, but hands the view down to one of the actors for subjective limited application from that person. Then, perhaps later in the chapter or in the next chapter, the omniscient person gets the view back, often just to hand it back down to the same actor or a new one. A good example of this is The Stand by Stephen King, but it's not rare. Tons of books are written this way. The issue is why one would have an omniscient narrator at all. People ought not pick a viewpoint form, just because they like it. It needs to fulfil the needs. You have articulated a good reason to have one because you want to see those two mice in the maze.