Scotty on Star Trek is not casting spells when he beams someone up, he's using a machine. That's very different from Gandalf casting a spell.
The only potential fundamental difference between a plot object like a crystal ball and a plot object like a transporter is whether there's a theoretical physical explanation for their function. If there is, then it's science fiction. If not, it's just fiction, and you may as well call it fantasy. It might not be witches-and-wizards fantasy, but it sure-as-hell ain't science fiction. You don't have to actually spell out the explanation, or even allude to it, but you should have one which works consistently with the idea of physics throughout your story if you want to be all sciency and stuff.