There are two kinds of light in this set. One arrives on its own at a time you can look up in a table. The other is carried in somebody’s hand, at an hour that was arranged, and paid for.

The second kind made the better pictures, and I want to be clear about what it was.
The evening before
Bromo is a working volcano in East Java with a caldera full of sand, a Hindu temple at the bottom of it, and a viewpoint on the rim where a few hundred people gather before dawn every clear morning. The flare frames are not from that morning at all. They were made the evening before, from sunset onwards, in a session the local operator arranged — horsemen, horses and flares on an open hillside with nothing else lit for miles.
The men were paid for it. I did not hand the money over myself and I do not know the figure, but it was a paid arrangement, and the pictures should be read that way: portraits made with willing subjects at an agreed hour, not something I came upon.
The flare

A hand-held flare, a horse, a man in a jacket, and a hillside with nothing else lit on it for miles. The light is orange, it moves, it throws smoke, and it falls off so fast that a step in the wrong direction loses the horse entirely.
None of that makes the frames less interesting to make. It changes what I am allowed to claim about them, which is a different thing.
Technically it is a straightforward problem and an unforgiving one. The flare is many stops brighter than everything around it, so the exposure belongs to the horse and not to the flame, and the flame will blow out. Let it. A blown flare with a correctly exposed animal beside it reads as fire. A correct flare with a black horse reads as nothing.

As the last light went, the flares took over from the sky, and earlier in the same hour the same subjects were simply silhouettes against purple. Same men, same horses, twenty minutes apart, a completely different photograph.
Sunrise, as advertised

The next morning we left at one o’clock. The jeeps, like the evening session, were organised by the local operator, and the drive up in the dark is part of what you are paying for.
Then the cloud came into the caldera and did what it is famous for, and several hundred people photographed it at the same moment, including me.
It is a good view and a dull photograph, and the reason is simple: nobody in it made any decision. The mountain was there, the cloud was there, the sun rose on schedule. I pressed a button at the same time as everyone else standing on the same concrete.

On the way down

Below the rim, people farm these slopes. By the time the sunrise crowd is driving back to breakfast the fields have been worked for two hours already. That frame took thirty seconds and no arrangement at all, and it is the one I would hang next to the flare.
The full Bromo set is on SmugMug.