Clinical photography 01 /certified fixed orthodontic courses by Indian dental academy


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  • Clinical photography 01 /certified fixed orthodontic courses by Indian dental academy

    2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
    3. 3. • Ever since the caveman began drawing on walls, it has been widely acknowledged that "a picture is worth a thousand words." • Nowhere is this truer than in dentistry. • Radiography depicts that which cannot be seen with the naked eye; photography documents that which can be seen.
    4. 4. • Photography is undoubtedly one of the most important inventions in history -- it has truly transformed how people conceive the world. • Now we can "see" all sorts of things that are actually many miles -- and years -- away from us. Photography lets us capture moments in time and preserve them for years to come.
    5. 5. • Photography is a universal means of communication and an invaluable tool in many fields. • From family snapshots to pictures taken from aircrafts, photographs record the people and the things we see, as well as many subjects beyond our range of vision.
    6. 6. • In skilful hands, a camera can transform an ordinary scene into an image of exceptional beauty.
    7. 7. WHAT IS PHOTOGRAPHY? • The word photograph comes from the greek words ‘Phos’ and ‘Graphien’. – Phos – light – Graphien- To draw • Literally – To draw with light • Photograph is a picture drawn with light.
    8. 8. • The art of photography has been in existence for well over a century. • It is best described as an art for the purpose that we likely to put it to; but in recent years, it has also become a science.
    9. 9. WHY PHOTOGRAPHY IN DENTISTRY?? • Patient education – Understand her/his condition – Need for treatment – Visualize potential improvements – Improves confidence – Evaluation of progress • Interactive treatment planning • Diagnostic aid
    10. 10. • Teaching • Publication / Clinical research • Communication with colleagues • Record keeping • Legal protection
    11. 11. CAMER A
    12. 12. • The term camera is shortened from camera obscura, literally "dark room" in Latin. • The camera is basically a box , with small aperture or opening where the lens is attached at one end and the film at the other.
    13. 13. • The inside of the camera must be completely dark , so that the rays of light reach the film only through the aperture.
    14. 14. PRINCIPLE • The camera works in much the same way as your eye. • The lens in the eye focuses the image on to the nerve cells in the retina and this image is sent to the brain by the optic nerve.
    15. 15.
    16. 16. • This is the principle employed in the camera. The lens sharply focuses the image on to the film. • To keep the image sharp even when the distance varies, the lens has to be moved either farther or closer to the film. This what we commonly call ‘focussing’.
    17. 17.
    18. 18. • The diaphragm of the camera is a variable aperture which controls the amount of light allowed onto the film, much in the same way that the iris of the human eye contracts in bright sunlight but opens when the room is dark.
    19. 19.
    20. 20. • The light reflects from a subject, enters the camera through the lens, which focuses the rays of light into an image on the film. • Light rays from the top of the subject form the lower part of the image and those from the bottom form the upper part. Thus the image on the film is upside down.
    21. 21. TYPES OF CAMERAS
    22. 22. • Single Lens Reflex (SLR) • Twin Lens Reflex (TLR) • Instant picture / Polaroid • Point and Shoot • Special cameras – Panoramic – Under water – Stereoscopic – Sub miniature (spy)
    24. 24.
    25. 25. TWIN LENS REFLEX
    26. 26.
    27. 27. COMPONENTS OF A 35mm SLR CAMERA Hot Shoe For Flash
    28. 28.
    29. 29. LENS
    30. 30. • Lens is a piece of transparent material that has at least one curved surface. • The lens is the heart of the camera, the component that turns the three dimensional world outside the camera into a two dimensional image on the film inside.
    31. 31. • Its job is to take the beams of light bouncing off of an object and redirect them so they come together to form a real image -- an image that looks just like the scene in front of the lens.
    32. 32. • The best way to understand the behavior of light through a curved lens is to relate it to a prism. A prism is thicker at one end, and light passing through it is bent (refracted) toward the thickest portion.
    33. 33. • A lens can be thought of as two rounded prisms joined together. Light passing through the lens is always bent toward the thickest part of the prisms.
    35. 35. • A lens produces its focusing effect because light travels more slowly in the lens than in the surrounding air. • Therefore, refraction (an abrupt bending of a light beam) occurs both where the beam enters the lens and where it emerges from the lens into the air.
    36. 36.
    37. 37. • Because of the curvature of the lens surfaces, different rays of an incident light beam are refracted through different angles. • Thus an entire beam of parallel rays can be caused to converge on a single point. This point is called the focal point, or principal focus, of the lens.
    38. 38. FOCAL POINT
    39. 39. • Refraction of the rays of light reflected from or emitted by an object causes the rays to form a visual image of the object. • This image may be either – real--photographable or visible on a screen or – virtual--visible only upon looking into the lens, as in a microscope.
    40. 40. • The focal length of a lens is the distance from the centre of the lens to the point at which the image of a distant object is formed.
    41. 41. FOCAL LENGTH
    42. 42. • A long-focus lens forms a larger image of a distant object, while a short-focus lens forms a small image.
    43. 43.
    44. 44. • The closer that you move an object to the lens, the larger it will appear on the film or photograph.
    45. 45. • The image may be much larger or smaller than the object, depending on – the distance between the lens and the object and – the focal length of the lens .
    46. 46. • There is a limit to how close you can move an object in order to enlarge an image size. • If you move too close to an object, with a lens which is not suited to that distance, then the image will get distorted. • This is one of the most important concepts in dental photography, with regard to lenses.
    47. 47.
    48. 48. TYPES OF LENSES
    49. 49. TYPES OF LENSES • Fisheye lenses – The fish eye is an ultra wide angled lens. – Typically it will have a focal length of between 6 and 16 mm – For shooting interiors or other confined spaces where an extreme angle of view is needed
    50. 50.
    51. 51.
    52. 52. Wide-Angle Lens – Includes focal lengths ranging from around 15mm through 35mm – Particularly well suited to landscapes and architectural photography
    53. 53.
    54. 54.
    55. 55. Normal / Standard lens – 50mm lens – Suitable for all general photography – Usually are the cheapest available for cameras
    56. 56. Telephoto lens • Short telephoto lenses range from 85mm to 250mm. • Long telephoto lenses range from around 300mm to 1000mm, and beyond. • Both these groups have multitude of uses including landscape photography, sports photography and wildlife photography.
    57. 57.
    58. 58.
    59. 59. • In addition, a short telephoto lens is considered ideal by many photographers for portrait photography.
    60. 60. Zoom lenses • Designed to have variable focal length from 24mm to 80mm, or 80 to 200mm, etc. • These are very handy pieces of equipment for, in one lens, you get two or three normal lenses. • Expensive, but when you consider that they take the place of two or three lenses these are quite economical.
    61. 61. 50mm 120mm 300mm
    62. 62. Macro lens • Macro-photography is a term that covers the photography of subjects on a life size scale (1:1) or larger than life size perhaps up to ten times (1:10).
    63. 63. • Macro lenses offer a stepless range of magnifications and shooting distances. • They make good portrait lenses.
    64. 64.
    65. 65. • Dental Photography: 100-105mm Macro lens • Some zooms can be set at a macro setting, although the image magnification is not as great. • In addition, because of the variable focal ability, it is almost impossible to make zoom lenses as sharp as a fixed focal length macro lens.
    66. 66.
    67. 67.
    68. 68.
    69. 69.
    70. 70.
    71. 71.
    72. 72.
    73. 73.
    74. 74.
    75. 75.
    76. 76.
    77. 77.
    78. 78.
    79. 79.
    80. 80.
    81. 81.
    82. 82.
    83. 83.
    84. 84.
    85. 85.
    86. 86.
    87. 87.
    88. 88.
    89. 89. • Depending on the preference of the photographer and the situation, a wide variety of choices can be exercised in order to get the required effect from the lens.
    90. 90. SHUTTER SPEED
    91. 91. • The purpose of the shutter is to protect the film from light until the chosen moment. • Simply put, the shutter speed is the length of the exposure time.
    92. 92. • Shutters have speeds ranging from ½ sec. to 1/8000 sec. • A fast shutter speed, 1/2000 sec., 1/4000 sec., etc means that the shutter is open only for a brief moment. • A slower shutter speed, 1/30 sec., ½ sec. means the opposite; the exposure is made for longer.
    93. 93. • Do not let the numbers on your camera confuse you. • A shutter speed shown as ‘2000’ means meaning very fast. 1/2000 – • The fraction indicator of 1/ is left out to ‘simplify’ things.
    94. 94. 1/30 1/1000
    95. 95. • Each speed will allow half as much of light strike the film as the preceding one. • For eg. – 1/30 will allow twice as much light as 1/60 would.
    96. 96. MECHANISM
    97. 97.
    98. 98.
    99. 99. • Usually, in Dental Photography, we have standard situations which are static. Therefore, the shutter speeds are also standard viz. 1/60
    100. 100. APERTURE
    101. 101. • The aperture is an opening through which the light passes from the subject to the film. • The aperture size is a measure of the size of that opening. • It controls the amount of light that is allowed to pass through the lens, and eventually strike the film.
    102. 102. • The aperture does this either by opening or closing , and allowing more or less light to pass through.
    103. 103. • Some lenses have a rotating ring on the lens barrel called the aperture selection ring. • Other cameras have an electronic dial to control this setting.
    104. 104. • The various sizes of the aperture are called ‘f’ stops or ‘f’ numbers. • The f-stops start from 1.4 and go up to 32. • Easy calculation: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32
    105. 105. • These numbers refer to the size of the LENS aperture, but not the diameter of the aperture. • The f number is the number by which the focal length of the lens must be divided to yield the diameter of the aperture
    106. 106. • For eg. – In a 50mm lens the lens is set to f/2 aperture. – Therefore the diameter of the aperture must be 50/2 i.e. 25mm. – Similarly, in a 100mm lens an aperture setting of f/2 means a diameter of 100/2 i.e. 50mm
    107. 107. • Caution: A 50mm lens set at f/8 will allow exactly the same amount of light that is allowed to pass through as does a 200mm lens set at f/8 200mm 50mm
    108. 108. • This can be expained on the basis of the Inverse Square Law. • The intensity of light is inversely proportional to the square of the distance that it travels. 200mm 50mm
    109. 109. • The 200mm is longer than the 50mm lens. • Therefore the light has to travel further to reach the film. 200mm 50mm
    110. 110. • Thus, on the 200mm lens the opening has to be bigger, at f/8, to allow the same amount of light as a 50mm lens set at f/8. 200mm 50mm
    111. 111. • Remember in this case too, the higher the number, the lesser the amount of light that is allowed to pass through. • Also one setting allows only half as much light as the preceding one would.
    112. 112. • For eg. – If you ‘open up’ the setting from f/11 to f/8 the aperture admits twice as much light – If you ‘stop down’ from f/11 to f/16, the aperture admits half as much light.
    113. 113. FILM
    114. 114. Types • Black & White • Colour • Colour reversal (for slides) • Also, Instant film (Polaroid)
    115. 115. Speed • Film speed is the amount of time required for the film to react to light. • The photographic film is similar to the radiographic film in this respect. • The photographic film is also composed of light sensitive grains (silver halide particles), which when exposed, produce an image of the subject.
    116. 116. • Thus, the larger the grains, the more sensitive it is to light. This is called a fast film. • A slower film would have smaller crystals, that are less sensitive to light. • However, smaller grains i.e. slower films always would produce sharper images vis-à-vis faster films with larger grains.
    117. 117. • Previously, film speed was either denoted with an ASA (American Standards Association) Number or a DIN (Deutsche Industrie Norm) Number. • Now film speed ratings have been standardized and are indicated by an ISO (International Standards Organization) Number.
    118. 118. • The film speeds available range from ISO 25 to ISO 3200. • ISO 25 being the slowest and ISO 3200 being the fastest.
    119. 119. • Slow (25- 64) films are used for stationary objects in a well illuminated scene or when fine detail is essential. • A fast film (400- 3200) is used for scenes that have dim light or involve fast action. • A medium (100-300) speed film is suitable for average conditions of light and movement.
    120. 120. • In this case too, as you move from one film number to the next, you would require twice as much light to get the same exposure. • E.g.. When you move from ISO 50 to ISO 100, you need half as much light for the ISO 100 to get the same photograph.
    121. 121. • For dental Photography, the ideal film would be ISO 100 that provides adequate sharpness and detail. • Light would not be a constraint in these situations as the conditions are static and well illuminated with a flash.
    122. 122.
    123. 123.
    124. 124.
    125. 125. EXPOSURE
    126. 126. • Exposure is the total amount of light reaching the film in the camera.
    127. 127. • If too much light enters the camera, the film will be over exposed and the picture will be too bright. • If there is insufficient light, the film will be under exposed and will result in a dark uninteresting picture.
    128. 128. • The three factors that affect the exposure are – Aperture setting (smaller number) – Shutter speed (smaller number) – Film speed (larger number)
    129. 129. • To obtain the correct image for your object, you must combine the three so that the correct quantity of light strikes the film. • Usually speaking, the shutter speeds and the aperture are variable, but the speed of the film is not.
    130. 130. • E.g. on a bright day, for a ISO 100 film the ideal settings for a static object are f/22 and 1/60 sec. • You need to shoot a fast object coming your way and change the shutter speed to 1/125 sec. Then you would need to compensate the aperture setting to f/16 for the correct exposure. • Vice-versa for aperture change.
    131. 131. • On a cloudy day, you may be better off loading a ISO 400 film rather than a ISO 100 film. • This would give you greater latitude in terms of selecting the shutter speeds and aperture controls. • Probably the sharpness may be compromised to a limited extent, but the trade off is worth it.
    132. 132. DEPTH OF FIELD
    133. 133. • A photographic term, which defines what is in focus within your shot, both in front of, and behind your point of focus. • In other words , it is the zone of the ‘in-focus’ elements in front and behind.
    134. 134.
    135. 135. Factors affecting DOF • Aperture size • Focal length of the lens • Distance of the subject from the camera
    136. 136.
    137. 137. • It should be noted that the depth of filed does not extend equally in front of, and behind, the point of focus. • As a general rule, the DOF produced by a particular lens will extend approximately onethird in front the point of focus, and two-thirds behind.
    138. 138. 1.4 4 22 8
    139. 139. • So how do we know what is in focus? Most 35mm SLR’s have a depth of field preview button. Looking through the viewfinder with the DOF preview button pressed down will give you a very good idea what is in focus and what is not.
    140. 140. FLASH & LIGHTING
    141. 141. • The two most important sources of light are – Natural – Artificial / Flash
    142. 142. •Using different combinations of the two can enable the photographer to obtain a wide variety of results, often with dramatic effects
    143. 143.
    144. 144. Hard Light Soft Light
    145. 145. • In dental photography, the flash gun is always employed, irrespective of the type i.e. I/O or E/O photography.
    146. 146. TYPES OF FLASHES
    147. 147. Built-in flash
    148. 148. Dedicated point flash
    149. 149. Ring flash
    150. 150.
    151. 151. Ring + Point Combo
    152. 152.
    153. 153. Important characteristics • Flash guide number- indicates how powerful the flash is. – A GN of 40 is adequate for dental photography when using an ISO 100 film • Recycle time: 5-10 secs
    154. 154. Synchronization • The duration of the electronic flash is very short, often less than 1/1000 second, and it goes off instantaneously. • Hence, flashes can be used at shutter speeds slow enough for the whole film to be exposed simultaneously. • This is where flash synchronization comes into the picture.
    155. 155. • If your shutter is adjusted to higher speeds as prescribed by the manufacturer, you may end up with partially lit photographs. • The shutter speed that is synchronized with the flash is often marked in red or has this sign marked next to it “ ”. • This shutter speed should be the one selected for dental photography.
    156. 156. Red-Eye • We've all see photographs where the people in the picture have spooky red eyes. Where do the red eyes come from?
    157. 157. Red-Eye • The red color comes from light that reflects off of the retinas in our eyes what you see is the red color from the blood vessels nourishing the eye.
    158. 158. Eliminating Red-eye • Many cameras have a "red eye reduction " feature. In these cameras, the flash goes off twice -- once right before the picture is taken, and then again to actually take the picture. The first flash causes people's pupils to contract, reducing "red eye" significantly. • Another trick is to turn on all the lights in the room, which also contracts the pupil.
    159. 159. • Red-eye normally occurs when the angle of the light, striking the subject and being reflected off o the camera is 2.5 or less. Thus, if possible, move the flash away from the camera. • You can also try bouncing the flash off the ceiling if that is an option. • Have the subject look slightly away from the camera.
    160. 160. Leader in continuing dental education