Real SF

I've been reading some ancient sf recently, mostly from around the 1920s and 1930s. In those days, the main writers of sf were science students. Many later became scientists, and used their foresight to write their novels. Asimov was another of the type, but I read most of his when younger, especially the robot books. Some stories are a little cheesy, and lack imaginitive plots, but they describe the science in layman's detail while trying to look ahead. Television was just on the horizon, so some stories include comms using the tv, but electrical inventiveness is a little lacking. They use high-power equipment with heavier and larger radio tubes and relays, little expecting the transister and everything that followed, like solid state.
Great though, and gives another viewpoint on which to build.
Sadly, writers are still held in the grasp of limited genres, and these change little. Fantasy and sf now seem to cover a wider range simply due to the lack of being able to assign it to a more suitable genre. People buying a title from the sf or fantasy shelf expect either the old-style sf or Hobbit-type fantasy, so can be disappointed with a really good book that is out of the standard genre.