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Article: Viktor Scherbakov

20215 Views - Nov 2015

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The Light in dental photography. The techniques of artistic photography.



Every year, dental photography becomes more and more interesting for dentists. Before you buy a camera you want to know what your camera is capable of. As a rule, before you buy the camera, you estimate the number of megapixels, sensor size, and lens quality and so on.

All these aspects are important, however, there is one main secret to getting really high quality photos, which many people don’t know: it is the light.

You can have the most expensive camera in the world, but without understanding the basic rules of using the light, you will be disappointed by the discrepancy between the expected image quality and the results.

However, if you know what equipment is used in photography for light and you are able to work with it, you can create stunning images with the simplest camera.



An article by Viktor Scherbakov



Modern dentistry cannot exist without the photography. The craft of photography is so closely intertwined in every day practice that today, it accompanies each clinical case.

And this is not surprising. Nowadays, with the rapid sophistication of methods of dental treatment and the increasing demand for complex aesthetic transformations, photography is becoming a great importance.

It is used to create a professional portfolio as a mean of communication between doctor and patient, as well as between members of the medical team; as a primary mean of motivation for patients and so on

Photography in dentistry has become so specific, complex, and multi-tasking that it can be considered a special kind of photography



Dental photography combines the principles of macro and micro photos, subject shooting and portrait photography. Today dental photography got a set of special equipment and accessories, which makes it possible to take pictures in difficult conditions of the mouth.



In order to work successfully in dental photography, you must have a general understanding of the principles of photography and the technical side of the ongoing processes. The process of shooting is based on the work of three major equipments: the camera, lens and flash.



The camera is essentially a device for storing light and the main body of the control process of photography. The main element of the camera is a light-sensitive sensor (matrix), which captures the light.



The lens is an optical system that allows you to focus light on the matrix of the camera. In dental photography, a special macro lens is used to get the image in a large size



Third, and most important technical element of photography is the flash. It allows you to illuminate the subject with the necessary amount of light. We will discuss further details concerning the flash.



Light is the most important element in photography. Light reflected from various objects and trapped in the matrix of the camera in the end, becomes a photo. Dental photography involves working on large degrees of magnification, the distance from the front lens to the teeth is very small – only 15-30 centimeters.



In dental photography, as with any macro photography, to increase depth of field, it is necessary to set a high aperture values (f20-32), which leads to the maximum closing of the lens aperture. In such conditions, the light is very difficult to penetrate through the lens onto the sensor. Using ordinary light, like the lamp in our office, we will get too dark frames. Therefore the flash is necessary.



Flash gives a short, but very powerful light pulse. Flash allows you to get focused, controlled intensity light which is required, in order to illuminate the subject.

In dental photography there are 5 levels of lighting, using different types of flashes and accessories.



Level 1 – ring flash



The first is the ring flash. (Fig. 1) the Most simple and uncomplicated lighting option in macro photography. Pulsed lamp ring flash is located around the front lens in the form of a circle, this allows you to get a good fill light even at very large scale imagery. Ring flash is easy to control and makes it easy to get good results. (Fig. 2) Also it is indispensable for the registration of occlusal photographs taken through a mirror. (Fig. 3)

The main disadvantages of ring flash are: sharp shadowless light with the formation of bright round spots on the enamel surface and objects under the ring flash often look flat and expressionless. Disadvantages of ring flash are especially noticeable when shooting the front teeth.



Level 2 – bipolar flash



The second level of illumination in dental photography is bipolar flash. (Fig. 4) These devices with dual lamps are mounted directly to the front edge of the macro lens and connected to one control unit. Flash can be tilted at different angles to the subject. This type of lighting allows you to get a more attractive form of glare, which is located on the side faces of the teeth, without closing an important detail. (Fig. 5)
The disadvantages of bipolar flash are: sharp light, leading to the formation of unnaturally bright glare, Dual-lamp systems, and also a limit on the maximum scale of shooting: if the lens is placed too close, the light may not be enough. When shooting chewing teeth in the larger scale of one of the lamps bipolar flash can get in a closed area (cheek retractor or cofferdam) that will not allow you to get a photo of a sufficient level of illumination.



Level 3 – bipolar flash on the bracket



The third level is a modified version of the bipolar flash lamps which are mounted on a special movable bracket. (Fig. 6) It allows you more freedom to configure the position of the lamp relative to the subject. In addition, the flash can be set to the special properties of light – soft boxes or boundary. (Fig. 7) Use them to soften the brightness of the flare, and get more attractive form of glare on the teeth. (Fig. 8)
The principle operation of the bouncer is that the flash light falling on the white surface of the reflector scatters and becomes softer. Mini diffusers reflect light through the diffusing screen, which also leads to softening of the flare.

This lighting option has the potential not only for standard photo-logging, but also for artistic photos.

The disadvantages of bipolar flash on the bracket is that the freedom of positioning of the lamps is limited by the mobility of the bracket. This system will be easy to get great shots in the traditional angles in simple configurations of lighting. However, for those who want to go beyond that, it is not enough.



Level 4 – remote bipolar system with mini soft boxes.



The fourth level of light in dental photography which opens up great opportunities for artistic photography and configures the most complex lighting schemes – remote bipolar system with mini soft boxes. (Fig. 9)
As light sources for this system, external flash are used with a swivel head. An ordinary power of these lamps for dental shooting is too much, so you should reduce the light intensity to 1/8-1/16 of the maximum pulse.



To connect flashes with a camera you can use the remote radio synchronizers, which provides accurate high-speed sync (about 1/300 of a second) at a distance of 100 meters, or use a built-in remote control available in some modern cameras. In some cases, the remote connection type allows you to use the automatic metering (TTL-control), so the adjustment of the power of the flashes must be set manually.



This system has no bracket. This provides maximum freedom of movement, however, the help of an assistant for flashes positioning is needed.



An important feature of the system is soft-boxes. These accessories allow you to get the most attractive pictures with a beautiful form of glare on the teeth. (Fig. 10)
A few words about the soft-boxes.
One of the main tasks of the photographer and the artist is to explore the nature of light. Sometimes the light is hard, and gives a pronounced contrast (direct sunlight / flash), and in some cases the light is soft (diffused lighting on a cloudy day, daylight, falling from a window).



Soft-boxes were designed to soften the harsh light from a small light sources (lamps, flash), and reduce the contrast of shadows and light spots. As a result, it helps to create a soft, natural lighting for taking pictures of people and other objects, such as teeth.



What’s inside the soft-box (Fig. 11): the flash light reflected from the inner silver walls, passes through the partition, and then through the front screen for diffusion of light. Due to the fact that the pulse of light passes through two scattering screens, light becomes soft. The form of glare is changing too. For this version of lighting, it is better to use a small soft box of approximately 25 by 25 cm.
The fourth level of lighting has several disadvantages: no automatic TTL control, the need to adjust the power of the flashes manually, requires the help of an assistant, and the impossibility of shooting occlusal photos through a mirror – specificity of this system makes it too uncomfortable.



Level 5 – bipolar flashes on stands with large soft-boxes.



Last, and most creative and promising, is the fifth level of lighting – bipolar flashes on stands with large soft-boxes. (Fig. 12)

As lamps can be used with Studio flash or the external flash that is used on the 4th level. The main difference of this system is that it uses larger soft boxes (50 by 50 cm and more) for shooting. The assistant will be uncomfortable to hold soft boxes in hand, so it’s best to fix them on special racks.



Large soft-boxes allow you to get even softer and more diffused light, with a beautiful form of glare. The reflection of a large soft-box on enamel restoration material and the gum allow us to show not only the optical structure and picture color, but also its volume, texture and relief. (Fig. 13)
Everyone has different ideas of beauty, but most photographers will agree – if we are talking about soft boxes there is one rule – bigger is better!



The disadvantage of the system of the fifth level is, first of all, the bulkiness. To change the position of the racks will not be easy. In the 5-th level similar to the 4th, there is no possibility to do the shooting in auto exposure control mode (TTL).



However, despite all the shortcomings, only the 4-th and 5-th levels have the potential to get really artistic photos. High-quality images are worth any inconvenience



Rules for the use of soft boxes



In order to successfully use the lighting system of the 4-th and 5-th levels, you need to know the General principles of work with soft-boxes.

If the flash is large, then size of the flare will also be large.

The following two photos show lighting schemes using soft-boxes of different sizes.

(Fig. 14 – Fig. 15) (Fig. 16 – Fig. 17)
If the soft box is closer, then the reflection and glare become more important?
Many believe that if you move the box farther away from the object, the light will be softer and more diffused. Actually, the light source becomes smaller and, therefore, higher contrast.
While using a soft box for photography, it is important to remember that at a closer distance from the object, the light will be softer. (Fig. 18 – Fig. 19) (Fig. 20 – Fig. 21)
If the angle of light is large, then shadows will be more contrasting.
If soft-boxes are located in front of the face of the patient, the light will fill the entire surface of the teeth without shadows. The image will appear too soft and bright. (Fig. 22 – Fig. 23)
If the flash is positioned at a large angle to the surface, the flare will be located on the side of the teeth. The shadow will become more contrasted. With this configuration, the surface texture is more obvious. (Fig. 24 – Fig. 25)
Changing the location of the light sources can get very good quality pictures.

Despite the opinion that the main and only purpose of dental photo is to have reliable information about the appearance and condition of the teeth, the doctors are more and more interested in art dental photography.



Artistic photos

Art photography is above conventional dental photography. It is not subject to the rules. It’s a real art. The main difference between art photography and conventional dental photography is its place in our dental life. These photos are made in order to put them on specialized Internet sites to demonstrate their professional level; for publications in journals; as a material for training programs and so on.



You should know that creating such works do not need some expensive professional equipment. All that is needed is an understanding of the behavior of light. It is important to know how you can achieve the desired lighting, how to position the light source relative to the subject, and how to choose the angle.

In art photography valid techniques are beyond the classic dental shooting. The main tool still remains a soft box.
The main rule of successful development of photo-art, is to practice and experiment as much as possible. We must always be open to free creativity. The process of photography is incredibly interesting, because at the slightest change of position of the flashes, the picture looks differently.

Conclusions

To find an interesting object for dental shooting, does not need unique clinical cases. Aesthetics can often be seen in the most ordinary things: interesting micro relief on the tooth, cracks in the erased cutting edge, custom enamel formation, and chewing teeth. If every dentist will learn to see the beauty through a routine, then we will all work with love. And the main tool in the way of understanding the aesthetics is photography!
 

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