One of my favorite photography books is Light Science and Magic. Understanding, and controlling, light is what photography is. Years ago, when I first started really experimenting with flash, I did a series of images based on the bright field/dark field techniques for illuminating glass. The book does an excellent job teaching these techniques. Most product photography involves back lighting the subject. This is particularly true for transparent objects like clear glass. The trick with glass is to show the edges of the glass, something very hard to do without precise control of what is lit (and what is not). I decided to revisit these techniques. I made this image showing the general concept of how to make glass edges visible:
I won’t go into detail as the book does a far better job than I can, but the essence of both is to have the edges reflect what the transparent middle of the glass does not. Understanding that a surface – including people’s surface (the skin) – reflects is a key concept in how lighting something works. We see, and the camera sees, using reflected or refracted light. The edges of the champagne flute are in fact reflecting what is just outside of the cameras frame – be it something light or something dark. Since the glass is transparent, it must be the opposite for the edges to be seen. Cool, huh.
No matter how glass is portrayed in an image, a variation of one of these techniques must be used.
Shooting glass can be challenging, yet at the same time very rewarding. Aside from keeping it (the glass) very clean (or doing lots of work in post), understanding bright field and dark field lighting makes the process manageable and forms the basis for creative and exciting photography.