====iPhone 4S, with HDR* on. HDR really helped bring out the sky. But there's been no post-production, no cropping even, only a slight sharpening which wasn't very necessary or visible. I'm a bit surprised at the nice light here, in reality it was quite dark and dull, it seemed to me.
(One has to be careful with holding the phone still in such dull light, since it doesn't have shake-reduction.)
*High Dynamic Range. To combine more exposures to help detail in highlight and shadow, in high-contrast situations. It's a poor situation that phone cameras have this now, while many real cameras still don't. (The great compact Sony RX100 does have it, but the otherwise very advanced system camera Olympus OM-D does not.)
PS: it was pointed out to me that this was more likely twilight than dusk, even though the sun seemed to have set. (And even though it seemed darker at the time than the pictures tell. As you may know, cameras tend to make everything equally middle-grey, so snow is grey, often, and coal is not black.)