CAD/CAM international magazine of digital dentistry

I 09 special _ digital photography I CAD/CAM 3_2012 control how far the lens is openedwhenapictureistaken. The farther the lens is opened, thegreatertheamountoflight thatisallowedintothecamera and the lighter the exposure. Once the aperture value has been selected, the camera au- tomatically selects the correct shutter speed to produce an acceptable exposure. By set- ting the aperture value, the photographer decides on the depth of field (the plane of sharp focus) in the image. One can select a small aperture value (a high f-number)foralargerplaneofsharpfocus(Fig.4)and alargeaperturevalue(asmallf-number)foranarrow plane (Fig. 5). A depth of field problem is that the entire denti- tion can only be photographed completely in sharp focusifthefocalplaneispositionedcarefully.There- fore,donotfocusontheanteriorteeth(yellowcircles onFig.4).Forafrontalview,thepointoffocusshould be around the canines (yellow circle on Fig. 5). Shutterpriority The shutter speed controls the amount of light that enters the lens when the picture is taken. The more light desired, the slower the photographer should set the shutter speed. Once the shutter speed has been selected, the camera automatically selects the correct aperture value to produce an acceptable exposure. This mode is not used for the purpose of intra-oral photography. Program The camera automatically selects both the aper- ture and shutter speed based on a built-in program. Manual The photographer selects both the aperture and shutter speed, but the camera’s built-in meter can still be used to calculate the correct exposure. For dental photography, it is important to be in control of the exposure features. Therefore, either the aperture priority or manual exposure settings are preferable. _Accessories for intra-oral photography Cheek retractors and intra-oral photography mirrors are essential tools for dental photography (Table I). Using these tools allows us as clinicians to teach and improve team involvement of all the staff. I feel that it is important to delegate the process of intra-oral photography to other members of staff; therefore, it is essential to teach and emphasis the standardisation of all the images taken so that any member of staff trained will achieve the high stan- dards required. Orientation of the image is important. The oc- clusalplaneshouldrunparalleltohorizontalframeof thephotographthroughtheview-finder,asaphoto- graph taken from below will distort and alter the perspective of the teeth. Lateral photographs should be taken perpendicular to the teeth using a mirror (Figs. 7, 8 & 11a). Lateral photographs without mir- rors will only show a few teeth, as the metered focus will be on the canines and first premolars (Fig. 11b). For occlusal views, the camera should be as near as perpendicular to the occlusal mirror (Figs. 9 & 10). Fig. 19Fig. 18 Tips for dental photography _Use cheek retractors; _Use dental photography mirrors (warm using the three-in-one to remove fogging and saliva bubbles); _If the image if too bright,increase the f-number (reduce aperture size); _If the image is too dark,decrease the f-number (increase aperture size); _Take as many photographs as you like,as you can delete them later. Tips for dental presentations _Use the crop tool to remove cheek retractors; _When using presentation software,use a black or white background for your images; _Don’t use too many transitions,as this can be distracting to the audience; _Definitely don’t use any sound effects. Table I Table II RecommendeddigitalSLRcamerasandtheirsettingsforintra-oralphotography Camera NikonDSLR CanonDSLR NikonDSLR Flash NikonR1C1flash SigmaringflashorCanonringflash Sigmaringflash Powersetting TTL eTTL 1/4 Aperturevalue F22 F25 F25 Shutterspeed 1/160 1/125 1/160 Table III Fig. 18_Cropping tool using GIMP. Fig. 19_The cropped image without the retractors using GIMP.