Monday, July 28, 2014
Photographing Clear Objects
Transparent subjects require special lighting techniques
|This Article Features Photo Zoom|
Lighting stuff is easy, right? You just point a light at it, and you can see it. But what if the thing you're trying to photograph is transparent—as in crystal clear? In that case, simply pointing a light at it won't work. You have to concern yourself with what can be seen through the object and with defining its edges in order to provide the shape. This is done mainly in two ways: on a dark background with light edges or on a light background with dark edges. Here's a simple technique for each approach.
When photographing a transparent subject on a light background, success will come from doing two things right: lighting the background and defining the edges. My preferred method with a tabletop setup is to use black glass as the foundation, with the table placed at least six feet from the white paper background. This way, I can light the background separately from the subject without worrying about spill and the mirror-like black plexi surface will reflect the bright background quite well.
I place a softbox below table height and centered on the background in order to evenly illuminate the white paper (or white wall) that will become the white background. Alternatively, two softboxes on either side of the table can also be used to evenly illuminate the background—although this method requires more attention to spill and flare, so flags may need to be positioned between these lights and the tabletop set. The benefit of one light below table height is flare is not an issue.
To define the edges of the clear object, I don't use lights. I use black flags or black foamcore sheets, usually about 2x3 feet in size for a subject smaller than a bread box. These act as negative fill. They reflect in the edges of the clear subject to effectively trace a dark line against the bright background. The position of those flags—how close to the subject and how far forward or behind—dictates the thickness and intensity of the outline. Sometimes, an additional flag placed above the subject is necessary to continue the outline across the top of the object. In the end, a single light is all it takes to make this shot work.
Clear Object on Black
The good thing about photographing a transparent subject on a black background is that you don't have to worry about lighting the background; you only have to make it dark. You could do this with a black seamless paper or black velvet drape positioned several feet from the tabletop in order to create a dark black background, and then position softboxes behind and to the sides of the subject, directed at the subject, in order to create the white highlight edges. But I've been leaning toward an even simpler method of achieving the same result, and it doesn't take much space at all. It uses a flag to create a silhouette behind the subject that's sure to go dark black.
This method is equally simple, allowing for some fairly refined lighting with only a single source. The key is to ensure you don't overexpose and make the black background dark or, even worse, middle gray. With the illumination coming from the exposed strips of softbox, it won't take much to set off the subject with white highlights against the black-silhouetted background.
Whether shooting on black or white, I find that the most important post processing adjustment is to contrast—ensuring deep blacks and bright whites—because after all, there shouldn't be many tones in between. Spotting and retouching of highly visible little blemishes and dust may be necessary as well, but in the end the success of these shots is largely a function of knowing how to light them. Remembering that you don't light a clear object—you light what is seen through it—is a great place to start.