Note: this is part I in a two-part series. Check in later this month for more dental photography tips!
Though camera phones are being used routinely to click selfies, overload Instagram accounts and create ASDA memories, their use in dentistry seems restricted. How can you bring that “oomph” factor to your clinical pictures? It is simple–stick to your basics and know them well! Although we are well acquainted with the different clinical pictures that need to be taken for patient records, what we generally tend to neglect are the basics to a good photograph. So, follow these steps and let the magic unfold!
The first step to a good click is to know the basic photographic terms to help you decide on your photographic requirements.
- Resolution: This means how much detail an image can hold. It’s measured in pixels. As the number of pixels increases, the image details become sharper. For dental use, generally 4-6 megapixels is good.
- Focal length: Focal length simply means the distance between the camera lens and the image sensor and is measured in millimeters. It tells you how “zoomed in” your pictures will be. The higher the focal length, the better the image captured. For dental use, a focal length of 50-85 mm should give you a high-clarity picture.
- Shutter speed: This indicates how long your camera shutter remains open. This speed is measured in fraction of a second like 1/9 or 1/200 and it controls the amount of light that enters the lens when a picture is taken. If more light is desired, the shutter speed should be lowered and you’ll need to hold still to get a good photograph. On your camera it is denoted by the letter “S.” For dental use, shutter speed of 1/125-1/160 is ideal.
- Aperture: This determines how wide the camera lens is opened. By setting aperture values, depth of field (plane of sharp focus) is determined. The more the lens is opened, the more light is let in resulting in a lighter exposure. Small aperture value (high f-number) is for a large plane of sharp focus. Large aperture value (small f-number) is for a narrow plane of sharp focus. On the camera it is denoted as “A” or “AV.” For dental use, AV 22-29 is suitable for intra-oral photographs, while AV 5.6-8 is ideal for extra-oral photographs.
- ISO: This is the light sensitivity of your camera’s sensor. Higher the ISO, more sensitive your camera will be to light and your images will appear grainier. For dental use, ISO’s of 80-200 is optimum.
The second step to ensure a good click is to have the right equipment–the right camera, lens, flash, cheek retractors and occlusal mirror.
- Camera: Today’s market is stocked with 2 types of cameras: point-and-shoot and DSLR (Digital Single-Lens Reflex). Of the two, the DSLR camera is preferred for dental photography. In spite of it being bulky and expensive, the increased image quality, fast operation and unlimited macro lens and flash options that the DSLR provides, make it the best candidate to click extra-oral and intra-oral pictures.
- Lens: The macro lens is an essential component in quality photography. Its ability to focus up-close and capture an image close to the actual size of the object is ideal for capturing pre-operative and post-operative images of teeth. Point-and-shoot cameras usually have a built-in macro feature that requires a minimum fixed focusing distance. On the other hand, the DSLRs have no prerequisites and also give the freedom to choose between different lenses based on your needs. However, DSLR lenses that give 1:1 magnification is generally desired, where object size captured on digital lenses equals the actual size of the object.
- Flash: A good picture always needs good lighting. The on-board flashes (built-in flash in point-and-shoot cameras and pop-up flash in DSLR’s) are inadequate for good images as shadowed and over-exposed areas are visible in the picture. An additional light source is required to overcome these errors, which can be easily tackled with the DSLR that allows for mounted flash systems (Ring flash or Dual-point flash). A ring flash is a circular flash unit fitted around the lens and is the preferred choice of the two for it allows uniform, flat and shadow-less illumination. But, surface texture and characterization might be compromised. This drawback is not seen with dual-point flashes, yet, it may produce images with shadows.
- Cheek retractors and Occlusal mirror: There are different sizes of cheek retractors available that can be used depending on your need. Care should be taken to moisten these retractors before use to avoid hurting the oral tissues. Try using long-handled occlusal mirrors for maxillary and mandibular occlusal shots as these are easy to handle while clicking pictures. Also, front-silvered mirrors offer better image quality and light distribution than glass mirrors or rear-silvered mirrors. It is advisable to warm the mirror/spray air continuously to prevent fogging of the mirror while taking occlusal shots.
- Always use a solid dark backdrop for extra-oral photographs simply to avoid reflection of light that may affect the quality of the image.
- Use saliva ejectors in patients who salivate heavily during photoshoots.
- For occlusal shots, ask the patient to open his mouth wide only after you have focused your camera, purely to avoid tiring the patient.
- Buccal mirrors are a good adjunct for indirect buccal shots of the dentition.
- Anterior contrasters are a fine addition in anterior shots where you want to “black out” the background and click either the maxillary or mandibular anterior teeth. This enhances the ability to appreciate translucency.
That’s it! The recipe to a good clinical photograph has been unveiled. Time to click those shutters and capture some amazing photos. Happy clicking everyone!
~Archana Menon, predental member