In most still-photo erotica, as exemplified by the Playboy centerfold, the composition is well-balanced. The sexual object is perfectly framed. The face, the torso, the crotch are centered. The object of desire is laid bare - there is no obscurity in what the viewer sees.
One reason erotica is so important is to give us this unobscured view of bodies - a view we so rarely get in real life. Even with a fully-nude lover, lights are often dim.
But this perfectionism to much erotica is what makes it so often seem clinical and unerotic. Unless you're a gynecologist or a bodybuilder, you rarely see bodies so well lit and well-framed in all their glory. It's the dim light, the obscured view, the accidental glance, the quick flash that arouses us in real life.
German painter Johannes Kahrs shows how the unbalanced frame creates more sexual tension than the centerfold. It's the combination of what we can and can't see that drives us wild.
This is why the peeping tom has more fun than the gynecologist.
