Paul Purcell , Jul 16, 2002; 05:59 p.m.
It's not actually reflective, it's the water acting like a lens: surface tension pulls the surface of the drop as much as possible into a spherical shape, which is just like most lens elements ( until the recent aspherical elements).
What you need to do is get close enough to focus on the drop, or in that picture's case, on the bulge the drop makes on the windshield. Then you focus on the image within the drop, so you'll need a close focusing lens.
I've seen the same effect using dew drops laying on horizontal flower leaves, transmitting the flowers, and using the drops of dew on a spider's web.
Dew as a lens