30 Photographing the lower jaw
Retractors keep the lips apart when the mandible is being photographed, too. The mirror used for photographing the upper jaw is also used here and is placed against the upper tooth arch. The photographer stands in front of the patient and indirectly photographs the tooth arch of the lower jaw using the mirror.
35-mm Photo Systems and APS System
For intraoral photography—macrophotography—SLR cameras with corresponding accessories (macrolens, flash) are indispensible for both the conventional 35-mm film format and the newer APS system.
The APS system uses a new, smaller film format (negative film) that stores all camera settings on magnetic strips. The APS film is exposed conventionally and then developed. The laboratory can later produce identical color prints by using the stored data. Furthermore, the APS system allows photos with classic, wide, and panoramic picture formats.
Because of its highly developed periphery, it is possible to transfer the pictures stored on photographic film via a video signal to a conventional TV screen for viewing. The picture can also be transferred via a digital connection to an APS player, processed by the computer, and be printed out. This could affect the dentist's decision in favor of the APS when deciding which new camera equipment to buy.
Camera Equipment
—SLR camera (APS or 35-mm film),
—Macrolens (90–120 mm focal length) that allows for a 1:1 magnification,
—Matching (TTL-attached) flash, usually ring or multiple side-flash version,
—Photographic film, for example, with standard 100 ASA speed,
—Cheek retractors and intraoral mirrors.
For intraoral photography it is important to use a camera system that allows for the use of a small aperture (usually f-32) in order to obtain maximum depth of field with the macrolens.
Examples of Conventional 35-mm Camera Systems
Two dedicated systems are especially suitable for dental close-up photography:
—Nikon Medical Nikkor (120 mm)
—Yashica Dental Eye II
Moreover, it is possible to put together a close-up system from the existing range of all major brands.
—Nikon F-601 AF or F50 with Nikon AF Micro-Nikkor 2.8/105 mm
—Minolta Dyuar 600 si classic or 500 si super with Minolta A-F Macro 2.8/100 mm
—Canon EOS 500 N or EOS 50 E with Canon EF 2.8/100 mm Macro
—Pentax MZ-5/10 or Z-70 with Pentax SMC-FA 2.8/100 mm Macro
—Sigma SA-300N/SA-5 with Sigma AF 2.8/90 mm Macro
The above-mentioned macrolenses are all original parts. For each brand, matching lenses (macrolenses at focal lengths of 90–120 mm) by companies such as Sigma, Tamron, Tonika etc. are also available that often cost half the price of the original brand names. It is difficult to decide which is the best system. It is probably still the best photographer who takes the best photographs, regardless of the system!
APS Camera Systems
The major camera manufacturers have recently introduced APS-SLR camera casings to which special APS lenses, conventional 35-mm lenses, or TTL-controlled external flashes (e.g., ring flashes) can be attached. APS systems suitable for dental close-up photography include:
—Canon EOS IX
—Nikon Pronea 600i
—Minolta Vectis S-1
31 Photograph of the upper tooth arch
A magnification of 1:3 to 1:4 is recommended.
32 Photograph of the lower tooth arch
A magnification of 1:3 to 1:4 is necessary.
Digital Camera Systems—Criteria for Selection
A new camera generation no longer records the pictures on a film but on an electronic memory chip. These pictures can be processed further on personal computers or shown on the monitor. Using a color printer such digitally recorded pictures can also be printed immediately.
Digital cameras contain a photosensitive chip (CCD sensor). This converts the picture into electric impulses (digital data). The image is stored in the memory chip, even when the camera is turned off. The image can be downloaded from the camera to the computer via a direct connection between camera and PC. Using a driver and image processing software, usually included in the purchase of such a camera, the photograph can be downloaded from the camera memory and transferred to the screen of a PC or a Macintosh, where it then can be processed. The quality of the picture depends on the pixel density of the chip, which determines whether the digitized picture is in focus or true color.
A few years ago, only professional photographers used the new technology because digital cameras were very expensive. However, relatively affordable appliances have been available for some time, whose pixel density still does not compare with that of professional cameras. The possibilities of the digital cameras are enormous. They are most suitable whereever the pictures need to be shown immediately and where there is a wish or need to process them further on the computer.
33 Professional digital camera, single lens reflex with changeable lenses, allowing wireless transmission of graphic files to the laboratory or other recipients. Additional professional Kodak cameras are the DCS 330, CDS 500, 520, 600, and 620.
34 With an appropriate printer, the images can be printed in photographic quality; here the Kodak Personal Picture Maker Kit is shown.
Resolution
The CCD sensors of a digital camera process information, which is expressed in pixels. The resolution is defined by the number of pixels per inch (ppi) or per centimeter (ppcm). The maximum picture format and the quality are determined by the pixel number.
Bit-depth
The bit-depth defines the maximum number of colors that a digital camera can capture. It not only determines the individual colors but also the hues and the shades of gray. If the gray is only divided into a few shades, an effect known as “posterization” will result.
No more than 256 (8 bits) shades of gray can be used by the usual computer programs during picture processing. Most digital cameras have a higher bit-depth. They dismantle the analogous data into 1024 (10 bits), 4096 (12 bits), or 16 384 (14 bits) steps. The computer then reduces the quantity of incoming data. Eight bits are available for each of the three primary colors, which means that it can process 16.7 million (256·256 ·256) colors.
Lenses
The quality of a picture is also determined by the quality of the lens. High-resolution, professional cameras with interchangeable lenses (e.g., Kodak of DCS 1 to DC 5, DCS 410 to DCS 460 with Canon or Nikon) are available. These modified 35-mm cameras offer a high picture quality, with, however, a concomitant large amount of image data. Only powerful computers with a large RAM can process this amount of data.
Normally,