Axial Lighting for Coin Photos

Axial Lighting

Axial lighting is a little-known technique which I think has great application in coin photography. In this technique, the light path travels straight back and forth along the same axis as the direction of the camera lens. Primarily used with microscopes or forensic photography, axial lighting can produce shadowless, yet high-contrast images with startling levels of detail.

An Axial Lighting Setup

As shown below, an axial lighting setup requires a flat and clear sheet of glass which is placed at a 45 degree angle to both the light source and the camera lens. Most of the light hitting the glass passes through it, but a significant portion of light is reflected downward at the subject - in this case, a coin.



You will notice that I've used a small black object to shield the coin from any direct light. I've also darkened the room to avoid any stray reflections in the glass. Therefore, the camera lens sees only the light reflected from the surface of the coin.

Here is one coin photo I took using axial lighting, with a black cloth used as the background...



What happens is that any smooth surfaces that are perpendicular to the light path, such as Liberty's cheek or the raised faces of the lettering of the coin, reflects a lot of light back to the lens and thus show up brightly. Any surfaces that are not perpendicular, such as the Liberty's profile or the edges of the lettering, reflect light away from the lens and show up darker. Smooth surfaces, such as the worn areas in Liberty's hair, show up very brightly. Slightly textured areas, such as the background field of the coin, show up darker.

In other words, there are no real shadows here, just brighter and darker areas, dependent on the angle, texture and reflective characteristics of each part of the coin. Note that I controlled the exposure in this photo so that the brightest areas would not wash out entirely. This makes the coin look somewhat darker than you would think from seeing it in person, but the emphasis here is on detail, not shine or luster.

This high degree of detail can be seen even more clearly in this larger version of the above photo...

Larger Axial Lighting Photo

Modified Axial Lighting

You can also control and modify the appearance of a coin with small changes in the angle of the reflective glass, causing the light path to be slightly off-axix, as in this example, where the glass was tilted just a couple of degrees more...



As you can see, even a small shift of the light off the primary lens axis loses some of the available detail, but it also restores the lustrous appearance of the coin.

Shooting a Darker Coin with Axial Lighting

Another advantage of axial lighting is that it can increase the contrast in a dark coin, such as an old copper cent. Such coins, shot with traditional lighting setups can sometimes look like featureless blobs, making it hard to see any significant detail. However, axial lighting and a well-chosen exposure can reveal much more...



In person, this coin is quite dark. To do it justice in an eBay auction, you might want to include both an axial lighting photo and another taken with conventional lighting.

Axial Lighting for Proof Coins

If you'll pardon the pun, the place where axial lighting really shines is with proof coins. The mirror finish of the fields on such coins makes them notoriously difficult to shoot. Any light striking such a mirrored surface at an angle will simply reflect away from the camera, leaving behind what look like featureless black pools surrounding the satin-finish design elements. Here is an inexpensive proof coin, shot with simple side lighting...



And here is the same coin, shot using axial lighting...




Choosing the Right Lighting for Your Coins

As I said when I started this coin photography series, there is no single approach which is best for all coins. In fact, more than one type of lighting can be used effectively  to show different aspects of a single coin. So, I would recommend experimenting with all of these techniques and even to invent variations of your own. The idea is to communicate with people about your coins. For that, a wide lighting vocabulary can be your best tool.