Dental Products Report | Web Exclusive
September 23, 2008

Shade matching photography

If you can’t afford the newest in shade matching technology, then a reliable digital camera, used properly, is still your best bet.

By Dave Hutt, Managing Partner for DMD Digital Dental Photography

	David Hutt

Accurate shade-matching is an on-going challenge for everyone. Right off the bat, the dynamics involved are so complex. There’s you and your patient, analyzing and comparing shade tabs by eye in an ever-changing environment. Ambient lighting, room color, time of day, and even personal factors all impact how we see color, and how that perception is so easily affected. Then, we try to communicate all that to the lab, with the expectation that they will use the information we provide to create color-accurate and patient-pleasing crowns and veneers. We shouldn’t be surprised when sometimes this doesn’t work.

So we try to use photography to minimize these variables and maximize our rate of success. Needless to say, digital photography has its own challenges, but these are more easily controlled, and the process can be made simple and reliable. The two key factors are: using the right equipment, and using the equipment right.

Using the right equipment

	Shot with Ringflash Shot with TwinLight

Forget the little “point & shoot” cameras; they’re great to take on your vacation, but sadly inadequate in your practice. The digital SLR cameras, with their larger sensors, superior electronics, and advanced firmware, will always produce greater color accuracy and image sharpness. The SLR is also capable of shooting in RAW format, which more and more labs are requesting. With an SLR, you can (and should) shoot with a true Macro lens, giving incredible image quality and maximum “depth of field” at up to 1:1 magnification.

With the SLR comes much more sophisticated lighting options, but where the traditional “ring flash” works fine for general intraoral photography, it is far less satisfactory for shade-matching. A ring flash places the light source directly on the lens axis, and this produces a harsh glare on the central anteriors. Glare means no color information and reduces surface texture and subtle opalescence. “Twin Lights,” or dual point-source lights, move the light sources a few inches off the lens axis, reducing those problems considerably.

What are some good SLR cameras? The Canon Rebel XSi , or the more advanced 40D, are excellent and affordable, as are the Nikon D60 and D80. Canon makes the popular MT-24 TwinLight; Nikon’s R1 Speedlight is likewise superb and affordable. Both can also be used for the full course of intraoral photography as well.

Using the equipment right

	Canon Rebel XSi Click here for full description.

The great thing about the SLR is that we have total control over shutter speed and aperture, which is vital in effective shade-matching and intraoral photography. With the camera set in the MANUAL mode, select a fast shutter speed/flash sync speed, which on most cameras will be around 1/160th to 1/250th of a second. This will allow you to comfortably hand-hold the camera and minimize movement and vibration, keeping the images looking clear and sharp. Select an aperture (“f-stop”) that will give the maximum “depth of field,” which on most Macro lenses will be f32. (“Depth of field” refers to the degree of apparent sharpness in front of, and beyond, the actual point of focus. Minimum, or shallow, “depth of field” looks like something generally out of focus).

So if the camera is set on its Manual mode, instead of one of its Auto modes, how do we get accurate exposures at varying distances? Easy—we make the flash do all the work. All these flashes, both the Ringflashes and the TwinLights, use what is known as “TTL” technology, “Through The Lens.” It allows the flash and the camera to communicate with each other, producing pin-point accurate flash output—and, consequently, exposure—every time, even as you move in closer or further away to frame your shots.

And finally, a word of caution: Never open up your files and “tweak” them before sending them off to your lab. Granted, it’s a hard temptation to overcome; we look at those photos we’ve just taken and know that we can improve the color, or make them a little lighter, and so on. But here’s the problem—you have probably never colorcalibrated your monitor (few dentists know what this is) and so what you’re seeing is not what the lab is seeing. Most good labs regularly calibrate their monitors, so that they conform to an ICC color standard, which ensures accuracy. It’s neither difficult nor expensive for you to do this, too, but that discussion is a little beyond the scope of this article.

It’s vital to understand that, even with all of this, digital photography is not a silver bullet that by itself will eliminate every problem and guarantee 100% results with your lab. No technology can replace good communication. Photography is but one element in that communication, albeit a very important one when done properly. Always make sure you know how your lab wants your files delivered, and in what format. If you’re ever uncertain about what these are or how they’re done, your lab will be delighted you asked them about it.

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Dave Hutt has been a professional photographer for over 30 years. He has spent most of the past decade as a consultant in digital photography, training commercial photographers, law enforcement personnel, and dental professionals in the use of digital technologies and lighting systems.

As a managing partner, and Training & Workshop Coordinator, for DMD Digital Dental Photography (www.dmddigitalphoto.com) , he teaches now solely in the dental profession. He has given presentations to the Tanaka Study Group, Oregon Health Sciences University, Astra Tech World Congress, and other study groups and dental associations throughout the U.S. He is a 1975 graduate of the University of Wyoming. You can reach Dave at dhutt@dmddigitalphoto.com to inquire about workshops and seminars at your location.