HT1776 - Visual Conventions

There are conventions in photography that influence what and how we produce our images. For example, it's a convention in photography that images representing dreams are soft focus and often have a heavy corner vignette. Images of pristine nature have crystal clear air and tack sharp details. Are these conventions inviolable, or is there a way to avoid conventions and still make a comprehensible image? I think of M. C. Escher and his images that blur the line between the subject and the background. Or Duane Michals who writes on his images with abandon. Breaking conventions is a great way to expand creative boundaries.