I know this is a cliché and hackneyed subject -- yet, when the sky at dusk explodes, it's hard not to look for the nearest camera. Which in this case was the Zf and Nikkor 400mm f/4.5Z.
The added benefit of this combination was it allowed me shooting hand-held at slow shutter speeds like 1/30-1/50 sec. After all, the sun had set long ago so darkness prevailed.