In my humble opinion, writing in the worlds of the fantastic is a very different prospect from creating a work set in the real world. Most people have some conception of the modern world. They know what a computer looks like, a car, a gun, the inside of a McDonalds. They may not have any idea what the writer of the fantastic is doing, what they are attempting to describe. Most people have a general idea of what a dragon looks like, a Tolkien elf. This may not be exactly like the dragon or elf I am trying to describe, but it gives a starting point. A reference to hang the details of my dragon or elf on. This actually becomes more of a problem with science fiction. I may be trying to describe a fifteen million ton battleship powered by matter-antimatter reactors, carrying hundreds of high gee missiles and a battery of lasers that can pump out terawatts of energy. Unfortunately, many readers may see the Enterprise, or maybe even the Galactica, images I am not trying to evoke. They may be used to seeing space fighters banking in a vacuum, not realizing that this is impossible. There is not air resistance to bank against in space. Sometimes a writer has to spell this out to his audience. Sometimes they get it. Sometimes not.
Back in the bad old days when science fiction could get away with wooden characters and stupid stories, as long as the setting was cool, writers could get away with using cheesy dialogue to get their point across. Fantasy didn’t have as big a problem with this, I guess because it dealt with settings that were already familiar in some ways to people from fairy tales and mythology. Science fiction, not so much. So they would have characters say things like “As you know Phil, the matter-antimatter injectors move antimatter into the reactors, where they annihilate each other and produce gigawatts of energy. And this is used to power the hyperdrive, which….” and so on. I can’t count on one hand the times I have used dialogue like this when giving someone a ride in my car. “As you know Pete, when I turn the key the gas is injected into the cylinders at the same time as a spark is generated in…” In fact I don’t need a hand to count how many times I have done this, which is never. I would have a reputation as a total idiot in my neighborhood. The secret is to try and get across the information with natural sounding dialogue, which means spooning it out a little bit at a time. Now I believe some description is OK. I have seen it used by a lot of successful modern writers. The missile leaving the tube and flying to the target. Dialogue might sound strange in this area. A weapons tech describing the flight of the missile to the captain, who should already be well versed in the dynamics of missile flight. And how little is too little. I have read several books where I didn’t have a clue as to what was going on until two thirds of the way through the story. And I only continued through innate stubbornness. I can imagine a number of readers who would have given up in the first quarter of the book, totally confused by the setting. I believe that the reader deserves to have a good grasp of the world, the technology, the politics, before the first quarter of the book has passed. Therein lies the challenge.
Doug BrotherofCats Dandridge 
Hello Doug
This is an aspect of your craft that makes me slap my forehead and say ‘of course.’ Writing description of place is hard for many fiction and cnf writers, and others worry about emoting too much or not enough. But to have to find words to describe what’s in your head when you’ve never seen nor touched nor felt it has to be a huge challenge, particularly when the audience has to be spoon fed to keep from imagining something already done. And those who read this genre tend not to like being coddled. A veritable Scylla and Charybdis.
Love your blog!
Medea