Here are a few photos from my experiments.I used my Nikon D810 with a 50mm, F 1.8 lens.
On a couple of websites/blogs I visited they recommended using a little dish soap in with your water and oil to give the bubbles a little more of a rounded shape. I tried it and personally was not fond of the mix. But, that is just me. You might find that you like the look. The photos below are some of my examples with the soap added.
Makes for some interesting and colorful macro photos to add to your collection if nothing else, lol.
Thank you for stopping by to have a look and
keep those cameras clicking!
Julie