Flash Systems for Dental Photography

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All digital cameras come with an “on board” flash. This is the flash located either on the top of the camera, or on the left side. For digital SLR cameras, the flash is usually a “pop up” style, and a button must be pushed to open it. Point and Shoot style cameras usually have a visible flash, which is located on the top or left side of the camera. While flash systems that come with a camera may be sufficient for recreational use, they are not always adequate for dental photography.

For a digital camera to focus efficiently on a subject, it must be able to read the contrast found in the image. The better the image is illuminated, the faster the camera will focus. This is especially true for Point and Shoot style cameras. If you have ever tried to take an arch shot with a Point and Shoot style camera – and the camera just keeps hunting for the focus – then you know what the output is going to be like. The computer chips found in the most recently released cameras are more sensitive, and require less light to focus. But additional light is still needed for Intra-oral Photography.

For digital cameras, the most common flash system used in dentistry is a ring flash. A ring flash emits light 360 degrees around the lens. This provides illumination to the subject from all directions. It is designed for up-close photography. This is different from the on board flash found on digital cameras.

The on board flash gives additional light from only one direction, usually from the top of the lens or from the left side. This causes problems in two areas. As previously mentioned, it makes it difficult to take intra-oral pictures. The light from the flash bounces off the cheek and lips while very little light actually enters the mouth. When a photo of a smile or a photo taken with retractors is used, the left buccal corridor will be fine but the right buccal corridor will be dark. The ring flash eliminates these problems. The ring flash emits light from all sides so sufficient light enters the mouth for intra-oral photos. It also lights up both sides of the mouth evenly. But, as with everything, there is a con that comes with the pro. The ring flash can do the job almost too well. While its job is to illuminate the entire field from all directions, the ring flash will also eliminate all shadows. This means the slight texture and anatomy, found particularly on anterior teeth, will not be seen. So teeth and veneers may appear to look ‘flat’.

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A twin flash solves this problem. A twin flash has a ring that attaches to the end of the lens like a ring flash. But it only has two flashes located on opposite sides. These flashes can usually be rotated around the ring and on their own axis, so they can be located in almost any position. You can  keep these at the 9 and 12 o’clock positions, pointed straight ahead. This provides light to both sides of a patient’s smile, and provides sufficient light to illuminate an arch. Though it does not remove all shadows, a photo of a smile taken with a twin flash will look much more natural than a smile taken with a ring flash. The colour quality will be the same, but even the slightest texture will be visible. The down side to a twin flash is its cost.

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Depending on the model, a ring flash will cost between Rs.24,000 and Rs.30,000. Meanwhile, a twin flash will cost from Rs.35,000 to Rs.56000. But, the twin flash is well worth it.

For Canon G series Point and Shoot cameras, both the Canon ring flash and twin flash will fit on easily. For Fuji and Nikon Point and Shoot cameras, ring/twin flash compatibility is a little complicated and you can consult with Mr.Sanjay Bajaj  at sb@iiirdi.in.

Meanwhile, you can also explore some Ring Flash options here:
http://www.thirdidigital.in/camera-accessories–flash-and-camera-lighting–ring-flashes

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