This is the first of a series of blog posts addressing photographic lighting techniques for transparent glasses.
Most photographers, especially in museum settings, are trained to photograph objects on flat, neutral backgrounds, and yet that approach creates incredible challenges when trying to capture subtle details—like engraving, tooling marks, optic ribbing, etc.—in transparent glasses. Often, it appears as if all detail disappears once the object is placed on the background.
Unlike most any other material, it is impossible to separate our perception of transparent glass from our perception of what we see through the glass. Every curve, every bit of engraving—really every change in the surface—in transparent glasses acts as a lens, however imperfect, and distorts the view through the glass.
Because detail is revealed through contrast of light and shadow, the field of view of each of these “lenses” must also include a contrast of highlight and shadow. If there is little contrast seen through the “lenses,” then there will be little contrast visible in the glass.
The first object covered in this series is an 18th century engraved wineglass from The Netherlands (79.3.993). I chose to begin with this object because it is colorless and has both blown and engraved elements.
Let’s start with some basics about the setup used for this series. All objects are photographed on a photo table with translucent white Acrylic (Plexiglas 2447) with a P95 (smooth matte) finish. This surface works well for both backlighting and surface lighting. Many different lighting types can be used, as long as they have matched color temperature and allow you to shape the light with beam control, flags, or masks. In these case studies, I have used high output LED BR40 lamps under the table and a variety of softlights and Fresnel (focusable spotlights) fixtures above the table. The translucent surface makes all of these techniques easier, but the optical principles remain the same, and lighting techniques controlling the contrast of a scene can be adapted for an opaque surface as well (Only surface lighting will be used for the second object in this series).
As this first example has demonstrated, our perception of transparent glass is a result of how it transmits, refracts, reflects, and distorts light. Armed with an understanding of these optical properties, we can reveal detail by exploiting the ways glass interacts optically with its surroundings in a carefully controlled lighting environment.