Welcome to a new ongoing feature in Digital Video, Adventures in Lighting, a monthly resource that will expand your understanding of light and lighting. For this first installment, I’ll discuss specular highlights, what they are and how to use them.
By definition, a specular highlight is a mirror reflection of the light source on the surface of your subject. It can also be described as direct reflection. Properly utilized specular reflections help to define the shape of a glossy or highly reflective surface such as glass or chrome.
The classic example is a wine bottle. Pictured is a beautiful bottle of 2003 Francis Ford Coppola Rubicon Cabernet Franc, a favorite of mine. As you can see, it’s a lovely dark bottle with very little fringe decoration. I’m going to use two ARRI 650W Fresnel lamps to light it.
If I use the lamps clean, what we see is a specular highlight of the lamps reflected off the black glass of the bottle—and they’re just points of light. It’s not pleasing; it’s not helping to define the shape of the bottle. There is light, but we’re not doing this beautiful, simple bottle any favors by just pumping hard light onto it. (fig. 1)
What we need to do is increase the apparent size of the light so it becomes a very large source reflected down the full length of the bottle.
In this case, I’m going to use large sheets of white foamcore—I’ll bounce the Fresnels into the foamcore. By evenly filling the foamcore with light from the 650W Fresnels, I turn a 6″ pinpoint of light into a 40″ x 60″ source of light.
Now what we’re seeing is the mirror reflection of the large sheets of foamcore in the glass of the bottle. The large reflection helps to reveal the bottle’s shape via silhouette. This is much more pleasing to look at than just the two spots of light and uses specular reflections to our advantage. (fig. 2)
This setup was a lot more complicated than just bringing in two large sheets of foamcore. The entire bottle is, for all intents and purposes, a mirror that reflects any source of light. I had to build up a lot of black around the bottle so as not to reflect myself or the room in the glass. Using duvetyn (black fabric) hanging on C-stands, I was able to surround the bottle in black. The bottle then reflects the black, which has no specific detail and makes the bottle’s surface appear smooth and clean. (fig. 3)
I also had to put up “siders,” solid black flags on the sides of the 650W Fresnels, to keep the lights themselves from being reflected in the glass. I simply used 24″ x 36″ cuts of black foamcore on C-stands for the siders.
The camera itself, and me behind it, was also reflected in the bottle; I remedied that by hanging a large piece of duvetyn in front of the camera and cutting out a small hole to fit the lens through. This erased any reflection of me or the rest of the room from the surface of the bottle.
Finally, I shot the bottle as if it were an advertisement. In which case, the name on the bottle is very important. Bringing out those gold letters against the glass was no easy task. I used a 150W ARRI Fresnel positioned very high and pointing down at the bottle, spotting in the light on the gold letters. I then brought in another black foamcore flag—as close to the bottle as I could get it without being in the frame—and used it to cut off the specular reflection of the 150W lamp from the upper curve of the bottle. You can see that specular reflection in figure 2, but it’s cut out of the final image by the flag. (fig. 4)
When you’re dealing with direct/specular reflection, it is handy to remember the law of physics that says that the angle of incidence is equal to the angle of reflection. In other words, the precise angle that light strikes a glassy/glossy surface is the angle at which it will be reflected. (fig. 5)
This point may be demonstrated by shining a laser light into a mirror; you’ll see that the angle of incidence (laser falling on mirror) is the exact angle of reflectance. This is an important rule to remember when using specular reflections, or when trying to remove unwanted reflections. Look at the reflection from the camera’s position and note the angle the camera is to the glossy surface, then trace that angle back to the offending (or creative) source. This can be a considerable challenge on a curved surface such as the wine bottle, but with some practice you’ll understand the principle.
This principle of specular reflections applies when photographing any glossy or reflective surface. In car photography, we use the same concept, but we utilize very large (typically 20′ x 40′ or larger) bounce or light sources to get a very large reflection in the surface of the car.
Any light source can have a specular reflection in a glossy/reflective surface. The larger the light source, the more the reflection will help to define the shape of the surface. Foamcore is an excellent source as it is very smooth, has no texture, and will appear as a smooth highlight.
You can use any light-colored material to create your specular highlight, but be careful how reflective the surface is—if your material has any pattern or texture to it, that may show up on the subject. I could have used a softbox to create my specular highlights, but any wrinkles in the front diffusion of the box would also show up in the highlight.
Take a look through your favorite magazine. You’ll see advertisements for cars, jewelry, drinks, silverware, even electronics—all employing specular highlights to show off the product’s beauty. Looking at these ads and deconstructing the lighting schema is a great way to expand your knowledge and experience when you don’t have a chance to play with the lights and toys yourself.