A few days ago I talked about placing the horizon high in the frame to emphasize foregrounds and make your main subject seem farther away. Before I get away from that concept, I wanted to show you how the balance of an image changes when you place the horizon extremely low in the frame.
With the horizon low you give emphasis to the sky or whatever else dominates the upper portion of your composition. I'll often do this with sunsets, for example, because the sky is generally the most colorful and interesting part of the scenes. But there are other times when I'll use a low horizon: if I'm photographing a lone tree on a hillside, for example, I'll keep the horizon low because I want to dramatize the isolation of the tree and it's small size compared to the sky or the hillside.
Horizon placement usually becomes instinctive after a while and I don't really think about it beforehand that much, but often I will shoot scenes both ways and then compare them later. It's free anyway, so why not make the extra effort. The one place most books will tell you not to place a horizon is directly through the horizontal center of the frame--and usually that's good advice--but rules are meant to be broken and sometimes it leads to startling visual discoveries. More about this in the days to come.