Two Principles, One Rule by Glenn Rand
Lighting Shiny Subjects

Many photographers have trouble lighting chrome or other shiny surfaces. While there are a lot of “Cookbook” solutions to lighting specific objects or specific looks, it is far easier to understand the two principles that control the lighting and the one rule to apply making it all work, regardless of the subject or light.

Principle One: Light Intensity
When lighting a shiny surface the light intensity within the total light envelope of the shot will determine how the final shot will look. Therefore, the ability for the photographer to modulate the light becomes key. This is true for adding and subtracting light intensity within the environment. Depending on the surface being lit, more lights may be needed than to simply give proper exposure to the subject but these lights will not shine on the subject.

There are three main ways that intensity can be modified. These are energy control on artificial light, blocking or partially blocking the light and using the Law of the Inverse Square.

The easiest to understand for most people is the electrical solution. Artificial lighting equipment sometimes allows adjustment of the power. Many lights have controls designed to adjust the light to lower intensity levels than maximum. Light can also be added to situations to increase the intensity. With lighting shiny objects, the off position for the switch of some lights may actually be the best way.

Lighting of “Resource Fork” Setting the Scene: The picture was shot from above with 4x5 view camera and offset with parallel shift to control angle of view and distortion. The black licorice for the background is taped down. The fork is raised on wires from underneath. Having the fork three inches above the background material allows reflective angles from below (behind) and away from the camera. Lighting: Black Plexiglas is used to allow for light to be reflected into the bottom of the fork. All lights are goboed or barn-doored to restrict direct light from reaching any part of the fork. Card #1: A large horizontal white card positioned above and behind the set fills the fork’s bowl and tines. Controlled light on the card from below creates an oval light pattern on the card. Card #2: A large white card behind and above the fork is angled to put a pattern of light (a blush) on the black enamel handle. Lighting the card fairly close from the side causes fall-off on the card, which creates an uneven reflection in the handle. Card #3: A small narrow card standing on the Plexiglas reflects fine lines on the camera side of the tines. Since the card is on the Plexiglas, the light can also bounce to reflect from the far tines. The light bounces into the card from the right side of the set. Card #4: This angled colored card above and to the camera side reflects a rich gold color into the forks’s gold accent. No light is shining on this card. Accent Light: This small specular light puts accents on the licorice.

The second way to control the light intensity is by blocking part of the light source. This blocking can be complete as with a “gobo” or partial, as with scrims or gels. It can also be important to remove light totally, beyond turning off or blocking lights. This is accomplished with flags or dark light absorbing materials.

The last of the three ways to modulate the light is by using the Inverse Square Law. Simply stated the law means that as the distance between the light and the light-catching material increases, the light intensity on the light- catching surface decreases. Conversely, as the distance is reduced the light increases in intensity. Therefore, moving lights closer or farther from the light-catching surface changes the intensity. Since both photographic stops and the law are based on a mathematical square function, it can be said that as you move the light twice further away you lose two stops of intensity. If you half the distance you gain two stops intensity. Photographed reflected intensity does not vary with distance of a lit surface from the camera, only varying with distance from the light(s) illuminating the reflected surface.

Principle Two: Law of Reflection
The angle of incidence equals the angle of reflection. That is the basic law of reflection. Unfortunately, it is not always simple to see because of what the law really means. The incident angle is measured from a perpendicular at each location. While flat reflective surfaces can cause some interesting problems, it is the curvilinear surfaces that make lighting more difficult.

Figure 1

In the simplest curvilinear shiny surface, a chrome cylinder, the point of reflection changes as the angle from the camera changes. When viewing straight into the cylinder the reflection of the camera is seen, though reduced. Here the camera’s viewing angle is perpendicular to the cylinder and the angle of incidence is 0° (see figure 1, page 15). In this case there is no reflected angle. Using a point on the cylinder one-third from front to back, the surface makes a 30° tangent angle with the camera (see figure 2, page 15), but the angle of incidence to that point is not the planar tangent angle of the surface but that amount subtracted from 90° (90°- 30° = 60°). At this point on the cylinder the camera will view a reflection of whatever is on a line going behind the cylinder at approximately 60° off axis (see figure 3, this page).

	Figure 2

The math is not practical for the photographer, so a directional fine-beamed light can be used to shine from the camera’s lens to determine what the camera will photograph. Using either a SLR or view camera the light can be placed on the ground glass or against the eyepiece to see where the light reflects. (A word of warning: Laser pointers can be used, but they can cause retinal damage if they shine in anyone’s eyes.) Using this technique the reflection in planar or curvilinear surfaces can be determined by seeing what the light coming from the light hits.

Figure 3

If the light reflecting onto a shiny surface is specular then the light reflecting off of it will be specular. The same is true for diffuse sources of light.

With these two principles, we can now apply the single rule that makes lighting shiny surfaces more than happenstance or cookbook.

The Rule
When lighting a shiny surface, do not light the surface, light what is reflected into the surface.

Any light shining onto a highly reflective surface can reflect directly into the camera. Hot spots (speculars) in the shot are unavoidable if the surface has a lot of curve and distortion and a specular light is illuminating the shiny surface. Therefore direct light on a shiny surface should only be used when speculars are desired.

The shape of a curvilinear surface determines when and where the light must be applied and reduced. But as mentioned above, these additions and reductions don’t happen for lights shining on the subject. A very convoluted shape can cause speculars that are generated by light reflecting within the shape.

Finn Knives 1998 by Glenn Rand

It is also important to determine how light transitions from lightness to darkness because these transitions will make up the dynamic tones in the shiny surface. If the transitions between intensities are abrupt on an open (large radius or planar) surface then the line between the lightness and darkness will be strong. Similarly, if the transition is gradual for the light reflected in this open area, there will be a gradient captured on the shiny surface.

	Al Reading 1989: The shape of the softbox’s light surface used for the exposure was modified by viewing through the view camera to create a smooth line on the complex surface of the car.

When thinking about the light envelope that the photograph will be made in, realize that the more control of potential reflected angles the better. Something black can disappear while something light can reflect in a shiny surface.

The size of what is reflected also affects the look of the photograph. And size is a relative concept. The relativity occurs because of the geometry of the photographic process. Both concave and convex surfaces expand the reflected environment. If optically large reflections need to be created then optically large light patterns are required. “Optically large” refers to the angle of coverage needed to reflect the light, not to its physical size. The further from the reflective surface, the larger the light pattern will need to be to accomplish the same amount of coverage.

Applying the Principles to the Rule
For highly reflective materials the camera must remain stationary, on a tripod or shooting stand that retains its single point of view.

Step 1: (Step one may be used many times—coming back to this step as required.) Determine what optical coverage light pattern is needed to fill a shiny area of your shot. Use material larger than the coverage needed. In this way there will be the ability to have more control of reflective effects.

Step 2: (Step 2 may be used many times.) Determine where light should not be in the reflection. Normally this is around the camera if it reflects but may be required by other concerns. Often photographers do not think about the dark, just the light.

Step 3: Tune the lights. Using either dimmers, scrims, gels, additional light or the distance of the light to the lighting material, achieve the amount of light desired for specific reflections. A spot meter can be used to read the intensity and adjust it in comparison to other lighting effects desired. Since the distance the reflection material is from the subject will not change its exposure value (only the distance the light is from the reflection material effects the intensity of reflections), the reflection material can be mover closer or further away depending on needs of lighting pattern. Working on one reflection at a time is recommended and accomplished by turning off all lights but the light being tuned and viewing the effect through the camera.

Step 4: Determine the overall lighting or directional lighting and effects for subject. Meter the subject as normal.

General Dos and Don’ts
Specular light tends to be more problematic than diffused light. Front reflections need camera side lighting material. Top and side reflections normally require lighting material toward the back of the set. When adding directional or camera side lighting, check specular reflection to make sure it reflects away from the camera and not into the scene. Use the shiny surface to add fill for other areas of the image.

Dr. Glenn Rand received his Bachelor and Master of Arts from Purdue University with a Doctorate from the University of Cincinnati. Photographs by Dr. Rand are in the collections of over 20 museums in the U.S., Europe and Japan. He has published and lectured extensively about photography and digital imaging ranging from commercial aesthetics to the technical fine points of black-and-white photography. Presently Dr. Rand teaches in the graduate program at Brooks Institute of Photography.