This is part intentional and part luck. I placed a box of Oreos in the background of this to give it some color. I illuminated it with one flash head while using the other to side-light the stream of water. I just KNEW that the Oreo box would be totally out of focus so nobody would suspect my cheap, kitchen-sink setup and trick.

But oddly, the lens-effect of the water stream brought the box into reasonable focus, particularly in the reflection of the stream. It's not what I intended, but I think I like it better than what I had in mind.

This was taken at 2 to 3 X magnification. I'm intrigued by the standing waves in the water stream near where it makes contact with the surface of the water in the little cup I was using.