People argue about the definition of "real" SF. Why? "Science" fiction should have some element of science in it, something so integral to the plot that removing it unravels the whole thing. Now, there are shadings of SF, just as there are in fantasy, and here is where most of the purists seem to stick their toes in. Especially, those who come on as the hardest of hard-science hard core SF seem to resent the existence of anything outside their field. Write what you want. Most of us are too busy enjoying the variety to quibble about categories.

Hard-core Science Fiction
Soft-core Science Fiction
Space Opera