Sometimes I go back through RAW files from a photo tour or workshop to see if I'd missed any good images. I found this one yesterday from my bats and birds workshop last year. I can't believe I missed it. What you are seeing are two different bats flying across an artificial pond, tripping the electronic beam which triggered two flash units. This flight sequence took place within a span of 30 seconds in which the shutter was open in pitch darkness. Everyone in the workshop got this shot because we all had our cameras pre-focused on the beam. The reflections of the bats in the water mirror the distance the animals were above the water. I find it especially compelling how the bat on the left opened its mouth. Bats come in to drink on the wing in the dry Sonoran desert in Arizona. My lens aperture was f/16, and the ISO was set to 1250. Magnify this image on your computer or phone and look at it closely. It's pretty intriguing.