Day 38 Setup...
Ok, here is a bit about my setup for this project... I went back and forth and made lots of changes before I ended up with the product.. and it was actually from the early tests... I will elaborate more....
1st tests, I set up and in manual, set for a black background by camera settings... 1st couple tests, the strobes were too low to properly expose the bubbles. As I made adjustments to improve bubble exposure, I lost my blackness and my blue sofa was in my picture.. I was not able to dial it out... I then decided I needed a black backdrop. I started with it propped on a tripod but light spill was too great so I moved it back to the back of the sofa. (in the photo's is a white backdrop I tried later).
Here are the setup photo's...
Overall setup.. I was in chair, left strobe was yougnuo 560 II, right side was SB - 700. Both units were always set the same as each other (manual Mode) Note that I started with Tripod like with drops but hard to target and time shot so I switched top hand held.
View from the command Chair!

My wife blew the bubbles, starting
from my left right at umbrella. Later she was on back side of umbrella.
Target and focus was center of umbrellas and center of paper. (autofocused on
her finger than sswitch to manual focus).
Shows relative setup from lights to backdrop...
Ok, issues... major was backdrop! Once I got the black, I had trouble keeping it black, seemed like when I had my best bubble exposure black was gray (sometimes splotchy) and as I tried to get it darker there was a lot of white spots (which I supect was reflections of spill light on other bubbles and/or some flare.) Never really solved that, so I tried removing the umbrella's, thinking maybe I would get less spill... I had a dark background but lost the good exposure on the Bubbles. After playing around, I went back to Umbrellas.
Still not satisfied, and realizing I was fighting the background, I switched to a white background. a couple exposure adjustments and the background was good (a little flare to lower left but not mottled or spotty and the bubbles were super crisp. I figured I had it!!! Did a series of shots, packed up and prepared to upload and process...
It was at that point, I was back to disappointment.... I will be back in a while to wrap this up and give you the final results and whys and wherefores...
Pat in NH