You may think that you're part of science fiction fandom purely by being a fan of science fiction, but apparently that idea misses some essential questions. For example, what kind of science fiction are you a fan of? And what kind of fan are you? Learn how to classify yourself and ask, "can't we all just get along"?According to the website Solar Flare, there's no such thing as SF fandom anymore:

I think there's a strong case to be made that historically there used to be one. The one that formed around the pulp magazines, that essentially created WorldCon and the Hugos. Members of that fandom were at one time a pretty good example of the average science fiction fan. But just like everything else in life, fandom has changed. For a star science fiction is a much broader umbrella than it ever used to be. Prose, graphic novels, movies, television all offer their own forms of science fiction with its own culture and following. But there are far more fan groups than just that. You have Star Wars fans, Star Trek fans, Hard SF fans, Soft SF fans, Harry Potter fans and on and on and on. With every year we get new fan groups that focus on their particular interests, splintering up fandom even further. And the ever advancing technology of the internet allows us to find people with exactly the same interests we have more easily than ever before... And there's another way that different fandoms have sprung up. Are you a convention goer? Do you interact almost exclusively on the internet? Or perhaps you're a member of a longer sci-fi group? All of these are forms of fandom, but they are significantly different forms that engage in different conversations and may get different enjoyment out of their fandom.

I'm not convinced that this is actually anything new; as soon as any kind of movement grows, it tends to splinter, even if it's a movement centered around one particular artist or whatever ("Their new stuff isn't as good as their old stuff!" "Yes, it is!" etc.). But I don't get why that means that there can't be - or isn't - such an overlap between each fanbase that creates some basic, "generic," SF fandom, or even that all these sub-sections can't be placed within the bigger genre picture. I mean, am I not a sci-fi fan because I didn't like The Dark Knight that much? ...Wait, I remember the comments after my review. Maybe it's better if you don't answer that. There's No Such Thing as Science Fiction Fandom [Solar Flare]