In “Focus, Vol. 1,” photographer Roman De Giuli follows colorful droplets as they roll along, chase one another, and burst. You may notice that many of the drops seem attracted to one another. This is actually a surface tension effect caused by the dimples the droplets create on the surface; it’s the same effect responsible for Cheerios clumping together in your milk. Interestingly, though, the oil coating the drops doesn’t seem to drain quickly enough for the clumping drops to actually coalesce. (Image and video credit: R. De Giuli)