I haven't yet downloaded the photos I took- that's a job for the weekend when I have the time to go through and check each one- usually it's just a case of cropping parts of people or objects caught on the edges of the picture. And I promised a couple of the authors I'd send them a copy of those they appear in.
I found out:
That there is hard sci-fi and soft sci-fi; the former is the really technical stuff that requires a lot of research (and probably a lot of technical understanding). While the latter, soft version, is more about the story/characters, often using the issues of the current time on a futuristic scenario, but usually not needing research.
(I'm working from memory here...)
World building; be consistent, even if you bend the laws of actual science. You can make your world do whatever you want, but you must be consistent.
Stephen Palmer (one of the guest authors) emphasised that for the mid-teen reader, plot and character were the things that mattered.
The good news is that sci-fi is no longer just male authors- as it was in the last century, and there are a few popular female authors in the genre.
Coincidentally 21st October 2015 was Back to the Future Day- the first film of the 'Back to the Future' trio.
There were lots of books for sale, and attendees had time to talk to the many authors who set up their table with their books. And every ticket holder got a goodie bag which included a couple of books.
Even though sci-fi isn't my thing, it was a good evening and I enjoyed it...