Greg Cox wrote:
It's possible to make a perfectly faithful adaptation that doesn't work at all as a film, or to take major liberties and still come up with a great movie or TV show.
I think the Harry Potter films are a good example. The first two films are pretty slavish to the surface content of the books, but to me they fail to embody the books' spirit and tone. The third and subsequent films take more liberties with the plot and details of the books (though still hewing pretty close), and come closer to capturing their spirit.
I think that it's an essential ambiguity in the OP question as phrased. Instead of asking for the "best film adaptation", to clarify, one has to, say, ask for "best film that's an adaptation" or "best adaptation of a book into film", and put the adjective "best" directly against the word you want it to modify and especially don't fuse "best", "film", and "adaptation" into the same noun phrase!
But my point is that such qualifications aren't needed, because the literal meaning of the word "adaptation" is "change" -- specifically, change that serves a constructive purpose when adjusting to a new context. It should be axiomatic that a film adaptation will make changes from the book. The question, then, is whether its changes work well, whether it manages to preserve what's important or add something new and worthwhile. Even those first two slavish Harry Potter films changed things, but they changed them in a way that I felt made them dull and prosaic, stripping away their sense of wonder (like having the Hogwarts stairways visibly rotate, as opposed to the books' description of having the corridors change topography in an unseen, inexplicable way that was far more magical). That was a change that took things away, whereas a good change -- a good adaptation -- will be one that adds something new or makes something work better.
I think the distinction is easier to see for adaptations that take a lot of liberties. This arguably isn't science fiction, but The Lord of the Rings
seems like a pretty good example, nevertheless. To some, Jackson's films are faithful adaptations; to others, the situation couldn't be further from the truth. I'm definitely in the latter camp. If I didn't know anything about the books, I'd have to agree that the films are very good. But since I do know what was cut out and changed, and since I'm missing certain things that were cut out big-time because I think they're essential, I have to say that I don't find the films to be very good adaptations. So, they are good films that are adaptations, but as adaptations, I find them to be very unsatisfactory.
Edited to Add:
In short, in the case of The Lord of the Rings,
I think a better adaptation of the books would have been possible that resulted in a better movie, that I would be wanting to rewatch, and that wouldn't have hurt the box office receipts in the slightest.
What one thinks of when speaking of "better this" or "better that", that's multiple topics of conversation in and of themselves, and it practically goes without saying that what is better depends upon the eye of the beholder. My point here in this post was simply to argue that there is a meaningful conceptual distinction, depending on which word "best" modifies, even if there is a great deal of overlap between the two, in how one way of looking at it feeds into the other.
I would agree that when making a film adaptation, the highest goal is to make a good film; fidelity to the original is of secondary, or lesser, importance. Perhaps that settles the issue, but I think it's worth mentioning that multiple film adaptations give one the chance to compare the adaptations themselves (e.g., The Time Machine, Journey to the Center of the Earth, The Andromeda Strain, Planet of the Apes, The Wizard of Oz
). Of course, what works for one audience at one time doesn't necessarily translate verbatim to another.
Silly me, there was an example before me in my first post that's squarely in sci-fi: Starship Troopers.
To purists, it's a bad adaptation because of the shift in tone, from serious to satire. That change produces in the movie a new work of art that truly is something besides simply a beat-for-beat "movie-ization" of the original. If one expects a completely straightforward "movie-ization" of the book, then one might well see a bad film resulting from a bad adaptation. Free of that expectation, and/or free of thinking that the tone of the original is worth being faithful to in a film made decades after the original was written, one might see the changes as improvements and/or deserving of being explored in their own rights. I definitely fall in the latter camp, there, on all counts.
is another film that I find great, that's an adaptation of a sci-fi book. I've not read the book, but I understand that there were some changes, and I also understand that not all people find the changes to be improvements.