Thanks to everybody who posted their comments and advice! I do agree that I should have focused more carefully on the first row of beads. Also, more DoF would have probably helped, although I felt that separating the first row of beads from the others was somehow important. I used such a shallow DoF because I was holding the plastic tube with my hands (you can see my fingers on the tube, if you watch carefully) during the 1-sec exposure. A smaller aperture would have required a longer exposure time, and motion blur would become visible in the reflections. Next time I'll try to secure things in place, somehow. :)
Very beatiful colourwise. The front row of the balls should have been tiny bit more in focus and then the DoF would have worked better in this case. (btw, love your camera setup).