I realize that this may make for a better video explanation than here with dorky pictures I draw, but I don't have time to put together a video... so bear with me.
Walter Murch talks a lot about editing and blinks in his excellent book on editing: "In the Blink of an Eye". If you are at all interested in filmmaking, this is a great read. Blinks are important. They are moments when the audience's brain says, "That was one thing, on to something else." They are mental shifts. So, ideally, you want your audience to blink when you cut.
The beautiful thing about editing is that you can force people to blink. That is why cutting on a great beat to a song, or on a gunshot works so well... the person naturally blinks.
But what if you discover that you can't ensure that the audience is going to blink on a particular cut that just isn't working?
First: How could you tell that? How can you tell when the audience is going to notice a cut? If you consistently feel the cut yourself, the audience is likely to feel something too.
Second: Don't use a cross-dissolve/cross-fade. Student films are riddled with these things. Major films have only a handful (and sometimes that's too many). In other words: Don't use a cross-fade unless you've got a good reason from a story standpoint to do so.
So, what do you do instead?
Borrow a lesson from magicians. They work a lot off of diversion: Make you look at something while they do something else.
So, question: What changes between these two shots?
The building disappears. True.
But what else?
The guy's arms move. If I kept the building the in background and transitioned from the one frame to the other, it would feel like there a "jump" in time. The guy's arms were in one place and now are in another.
But by making the building vanish (a big change), the small movement of the guy isn't noticeable.
Static images aren't the best way to demonstrate this truth, but I've been using this very trick in the art video that I finished a rough cut of this afternoon. Look for ways that filmmakers force or fake blinks in the films and television shows you watch this week.
Your Media Production Mentor