I recently spend a few hours exploring photographing water drop refractions with a small group of photographers. And the results were quite beautiful and relatively easy to come by.
Your DSLR of mirrorless camera and a macro lens mounted on a tripod is the basic equipment you need. Lighting is minimal. A small LED light or even available light will do the trick. I’ve used my cell phone’s flashlight. Since your camera is on a tripod exposures can be quite long. Of course, your off-camera flash can be quite useful as well.
Water drops are essentially spherical and act as a lens that is focused on whatever is behind it. So a colorful, interesting background image such as a flower or even an image on your computer screen will work. Use your imagination and get creative. Next you’ll need something for the water drops to rest on. A blade of grass or a twig for example. Set this up in front of the background using paper clips, clothespins, small clamps, etc. There will be some trial and error getting everything set up and spaced proper. The background should be far enough behind the drops so it will be completely out of focus. Next bring your camera as close as possible to the drops and still be able to focus on them. The drops will in turn be a perfectly focused refraction of the background. The hardest part is getting the drops to be full and spherical enough – and to stay put. I’ve heard that adding a little glycerin to the water helps with the drop formation.
Water drop refraction photography can be quite rewarding. There will be some trial and error getting your set up working well but the results will be surprisingly beautiful. A great way to exercise your creativity.