Dental photography is an essential part of the Facially Generated Treatment Planning process. It requires the right equipment and camera settings to ensure that the photos taken are useful for co-discovery and case presentations.

The process of producing a photo involves creating an “exposure.” When light passes through the camera lens, it hits a sensor within the camera. The exposure of light on to the sensor creates the image that we see. Different iterations of equipment and settings affect how much light hits the sensor. In turn, this affects the image that is obtained. To have an adequate exposure for clinical dental photography, it's important to have the proper camera components and settings.

Dental Photography Camera Components

The basic set up for clinical photography consists of a camera body, macro lens, ring flash, and SD memory card.

Camera set up for dental photography
Figure 1: Camera set up for dental photography.

The camera body is the main component in the camera set up. It contains the viewfinder, mirror, shutter, and image sensor. In essence, a camera body is a light proof box. When the shutter opens, this allows light to hit the sensor which results in an exposure. The camera body is also the element where the settings can be adjusted to control how much light is being exposed to the sensor.

In addition to a camera body, a macro lens is necessary for dental photography. This lens is a special camera lens that is designed to focus on objects that are positioned in close proximity (typically within one foot) of the lens. Because of how close we are to our patients when taking clinical photographs, a macro lens is ideal for producing sharp, crisp, and in focus intraoral images.

Camera body (left), macro lens (middle), macro lens attached to camera body (right)
Figure 2: a) camera body b) macro lens c) macro lens attached to the camera body.

A ring flash is a uniquely designed flash system that attaches to the front of the lens. This creates additional lighting close to the subject. A ring flash is beneficial for dental clinical photography because it produces the lighting necessary to illuminate the oral cavity. In many cases, an adapter is necessary to connect the ring flash to the lens.

Ring flash and adapter
Figure 3: Ring flash and adapter (seen on the lower left of the image).

Finally, an SD card is used to store images that are taken. The SD card is analogous to film in analog photography. When an exposure occurs, the data is recorded on the SD card. This data is stored as a digital image that now can be used to view the resulting photograph.

Camera SD card
Figure 4: SD card.

The Three Fundamental Camera Settings

Once the camera components have been assembled, there are three basic camera settings to consider: ISO, shutter speed, and aperture.

The triad for proper exposure: ISO, Shutter Speed, and Aperture
Figure 5: The “triad” for the proper exposure.

The ISO is analogous to film speed with traditional film cameras. Historically, film that has a higher ISO value was considered more beneficial for low-light environments. With digital cameras, the ISO can also be adjusted for dark or bright environments to help adequately expose an image.

The shutter speed is the second setting that plays a role in dental photography. The shutter speed dictates how long the camera's shutter stays open when an exposure occurs. The longer the shutter is open, the more light will be captured on the camera's sensor. If a shutter speed is too short, the image will be “underexposed” and will appear dark. If a shutter speed is too long, the image will be “overexposed” and will be too bright.

Differences in camera exposure on images of a baseball: underexposed (left), overexposed (middle), proper exposure (right)
Figure 6: a) too short of a shutter speed results in an underexposed image b) conversely, too long of a shutter speed leads to an overexposed image c) a properly exposed image due to an adequate shutter speed.

The aperture is the third setting that is important to consider in dental photography. The aperture is a hole or diaphragm in the lens that controls how much light passes through the lens and hits the sensor. The size of the aperture opening in the lens is recorded as the “f-stop.” This dictates how wide or narrow the diaphragm is in the lens. The more open the aperture, the more light passes through. The aperture is recorded in an inverse manner. For example, an f-stop of f/4 is a larger diameter opening than an f-stop of f/22.

Aperture and f-stop diagram demonstrating camera shutter at f/5.6, f/8, f/11, f/16, and f/22.
Figure 7: Aperture and f-stop.

In addition to controlling the amount of the light that hits the sensor, the aperture also plays a role in the “depth of field.” The depth of field refers to how much of the image is in focus. A larger aperture (such as an f/4) will have a much shallower depth of field than a smaller aperture (such as an f/22). Larger apertures tend to be used in portrait photography, whereas smaller apertures are more commonly used in landscape photography.

Aperture demonstrated in three different photos with f-stop adjusted to f/5.6 (left), f/10 (middle), and f/22 (right)
Figure 8: Aperture and depth of field. Notice how more of the background is in focus as the f-stop adjusts from f/5.6 to f/22.

Dental Photography Camera Settings

Knowing that there are multiple settings for ISO, shutter speed, and aperture, which are the most appropriate for dental photography?

Typically, an ISO of 100 is considered the most ideal setting for dental photography. The ideal shutter speed for dental photography is 1/125 sec. The aperture will vary depending on if extraoral or intraoral photos are taken. A f-stop of f/8 to f/11 works well for extraoral photos, whereas a f-stop of f/22 to f/32 provides the best depth of field for intraoral photos.

Headshot of patient
Figure 9: Extraoral photo taken with an aperture setting of f/9.
Intraoral full mouth with aperture f/22
Figure 10: Intraoral photo taken with an aperture setting of f/22.

Finally, for the ring flash a “through the lens” setting is the most ideal for dental photography. This will commonly be represented as a “TTL” or “ETTL” setting on the camera flash. A through the lens setting enables the camera to auto-adjust the flash in order to minimize the risk of overexposing or underexposing an image.

Basic camera settings: ISO - 100, Shutter Speed - 1/125 sec, Aperture/f-stop - Extraoral: f/8-f/11; Intraoral: f/22-f/32, Flash - Through the lens (TTL)
Figure 11: The basic camera settings for clinical dental photography.

In future articles, we will explore patient positioning and troubleshooting for clinical dental photography.

Andy Janiga, D.M.D., practices at the Center for Dental Excellence in Nashua, N.H., and is a contributor to Spear Digest.