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CLINICAL
PHOTOGRAPHY
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

www.indiandentalacademy.com
• Ever since the caveman began drawing on
walls, it has been widely acknowledged that "a
picture is worth a thousand words...
• Photography is undoubtedly one of the most
important inventions in history -- it has truly
transformed how people concei...
• Photography is a universal means of
communication and an invaluable tool in many
fields.
• From family snapshots to pict...
• In skilful hands, a camera can transform an
ordinary scene into an image of exceptional
beauty.

www.indiandentalacademy...
WHAT IS PHOTOGRAPHY?
• The word photograph comes from the greek
words ‘Phos’ and ‘Graphien’.
– Phos – light
– Graphien- To...
• The art of photography has been in existence for
well over a century.
• It is best described as an art for the purpose
t...
WHY PHOTOGRAPHY IN
DENTISTRY??
• Patient education
– Understand her/his condition
– Need for treatment
– Visualize potenti...
• Teaching
• Publication / Clinical research
• Communication with colleagues
• Record keeping
• Legal protection

www.indi...
CAMER
A

www.indiandentalacademy.com
• The term camera is shortened from camera
obscura, literally "dark room" in Latin.
• The camera is basically a box , with...
• The inside of the camera must be completely
dark , so that the rays of light reach the film
only through the aperture.

...
PRINCIPLE
• The camera works in much the same way as
your eye.
• The lens in the eye focuses the image on to the
nerve cel...
www.indiandentalacademy.com
• This is the principle employed in the camera.
The lens sharply focuses the image on to the
film.
• To keep the image sha...
www.indiandentalacademy.com
• The diaphragm of the camera is a variable
aperture which controls the amount of light
allowed onto the film, much in the...
www.indiandentalacademy.com
• The light reflects from a subject, enters the
camera through the lens, which focuses the rays
of light into an image on ...
TYPES OF CAMERAS
www.indiandentalacademy.com
• Single Lens Reflex (SLR)
• Twin Lens Reflex (TLR)
• Instant picture / Polaroid
• Point and Shoot
• Special cameras
– Pan...
SINGLE LENS REFLEX

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TWIN LENS REFLEX

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COMPONENTS OF A 35mm SLR
CAMERA
Hot Shoe For Flash

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www.indiandentalacademy.com
LENS

www.indiandentalacademy.com
• Lens is a piece of transparent material that has
at least one curved surface.
• The lens is the heart of the camera, the...
• 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 i...
• 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...
• A lens can be thought of as two rounded
prisms joined together. Light passing through
the lens is always bent toward the...
CONVERGING
OR
CONVEX LENS

DIVERGING
OR
CONCAVE LENS
www.indiandentalacademy.com
• A lens produces its focusing effect because light
travels more slowly in the lens than in the
surrounding air.
• Therefo...
www.indiandentalacademy.com
• Because of the curvature of the lens surfaces,
different rays of an incident light beam are
refracted through different ...
FOCAL POINT

www.indiandentalacademy.com
• Refraction of the rays of light reflected from or
emitted by an object causes the rays to form a visual
image of the obj...
• 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 obje...
FOCAL LENGTH

www.indiandentalacademy.com
• A long-focus lens forms a larger image of a
distant object, while a short-focus lens forms a
small image.

www.indianden...
www.indiandentalacademy.com
• The closer that you move an object to the lens, the
larger it will appear on the film or photograph.

www.indiandentalac...
• The image may be much larger or smaller than
the object, depending on
– the distance between the lens and the object
and...
• 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 ob...
www.indiandentalacademy.com
TYPES OF LENSES
www.indiandentalacademy.com
TYPES OF LENSES
• Fisheye lenses
– The fish eye is an ultra wide angled lens.
– Typically it will have a focal length of
b...
www.indiandentalacademy.com
www.indiandentalacademy.com
Wide-Angle Lens
– Includes focal lengths ranging from around
15mm through 35mm
– Particularly well suited to landscapes an...
www.indiandentalacademy.com
www.indiandentalacademy.com
Normal / Standard lens
– 50mm lens
– Suitable for all general photography
– Usually are the cheapest available for
cameras...
Telephoto lens
• Short telephoto lenses range from 85mm to
250mm.
• Long telephoto lenses range from around
300mm to 1000m...
www.indiandentalacademy.com
www.indiandentalacademy.com
• In addition, a short telephoto lens is considered
ideal by many photographers for portrait
photography.

www.indiandenta...
Zoom lenses
• Designed to have variable focal length from
24mm to 80mm, or 80 to 200mm, etc.
• These are very handy pieces...
50mm

120mm

www.indiandentalacademy.com

300mm
Macro lens
• Macro-photography is a term that covers the
photography of subjects on a life size scale (1:1)
or larger than...
• Macro lenses offer a stepless range of
magnifications and shooting distances.
• They make good portrait lenses.

www.ind...
www.indiandentalacademy.com
• Dental Photography: 100-105mm Macro lens
• Some zooms can be set at a macro setting,
although the image magnification is...
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
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www.indiandentalacademy.com
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www.indiandentalacademy.com
www.indiandentalacademy.com
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www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
• Depending on the preference of the
photographer and the situation, a wide variety
of choices can be exercised in order t...
SHUTTER SPEED

www.indiandentalacademy.com
• The purpose of the shutter is to protect the film
from light until the chosen moment.
• Simply put, the shutter speed is...
• Shutters have speeds ranging from ½ sec. to 1/8000
sec.
• A fast shutter speed, 1/2000 sec., 1/4000 sec., etc means
that...
• Do not let the numbers on your camera confuse
you.
• A shutter speed shown as ‘2000’ means
meaning very fast.

1/2000

–...
1/30

1/1000

www.indiandentalacademy.com
• Each speed will allow half as much of light
strike the film as the preceding one.
• For eg.
– 1/30 will allow twice as m...
MECHANISM

www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
• Usually, in Dental Photography, we have
standard situations which are static. Therefore,
the shutter speeds are also sta...
APERTURE

www.indiandentalacademy.com
• The aperture is an opening through which the
light passes from the subject to the film.
• The aperture size is a measure...
• The aperture does this either by opening or closing ,
and allowing more or less light to pass through.

www.indiandental...
• Some lenses have a
rotating ring on the lens
barrel
called
the
aperture selection ring.
• Other cameras have an
electron...
• 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.
• E...
• These numbers refer to the size of the LENS
aperture, but not the diameter of the aperture.
• The f number is the number...
• 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. 25m...
• 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 20...
• This can be expained on
the basis of the Inverse
Square Law.
• The intensity of light is
inversely proportional to
the s...
• The 200mm is longer
than the 50mm lens.
• Therefore the light has to
travel further to reach
the film.

200mm

www.india...
• 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/...
• Remember in this case too, the higher the
number, the lesser the amount of light that is
allowed to pass through.
• Also...
• 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’ fro...
FILM

www.indiandentalacademy.com
Types
• Black & White
• Colour
• Colour reversal (for slides)
• Also, Instant film (Polaroid)

www.indiandentalacademy.com
Speed
• Film speed is the amount of time required for
the film to react to light.
• The photographic film is similar to th...
• Thus, the larger the grains, the more sensitive it
is to light. This is called a fast film.
• A slower film would have s...
• Previously, film speed was either denoted with
an ASA (American Standards Association)
Number or a DIN (Deutsche Industr...
• The film speeds available range from ISO 25 to
ISO 3200.
• ISO 25 being the slowest and ISO 3200 being
the fastest.

www...
• Slow (25- 64) films are used for stationary
objects in a well illuminated scene or when fine
detail is essential.
• A fa...
• 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 ex...
• For dental Photography, the ideal film would
be ISO 100 that provides adequate sharpness
and detail.
• Light would not b...
www.indiandentalacademy.com
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EXPOSURE

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• Exposure is the total amount of light reaching
the film in the camera.

www.indiandentalacademy.com
• If too much light enters the camera, the film will be over
exposed and the picture will be too bright.
• If there is ins...
• The three factors that affect the exposure are
– Aperture setting (smaller number)
– Shutter speed (smaller number)
– Fi...
• To obtain the correct image for your object, you
must combine the three so that the correct
quantity of light strikes th...
• 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 sho...
• 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 ...
DEPTH OF FIELD

www.indiandentalacademy.com
• A photographic term, which defines what is in
focus within your shot, both in front of, and
behind your point of focus.
...
www.indiandentalacademy.com
Factors affecting DOF
• Aperture size
• Focal length of the lens
• Distance of the subject from the camera

www.indiandent...
www.indiandentalacademy.com
• It should be noted that the depth of filed does
not extend equally in front of, and behind, the
point of focus.
• As a g...
1.4

4

22

8

www.indiandentalacademy.com
• So how do we know what is in focus?
Most 35mm SLR’s have a depth of field
preview button.
Looking through the viewfinder...
FLASH & LIGHTING

www.indiandentalacademy.com
• The two most important sources of light are
– Natural
– Artificial / Flash

www.indiandentalacademy.com
•Using different combinations of the two can
enable the photographer to obtain a wide
variety of results, often with drama...
www.indiandentalacademy.com
Hard Light

Soft Light

www.indiandentalacademy.com
• In dental photography, the flash gun is always
employed, irrespective of the type i.e. I/O or
E/O photography.

www.indi...
TYPES OF FLASHES

www.indiandentalacademy.com
Built-in flash

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Dedicated point flash

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Ring flash

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Ring + Point Combo

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Important characteristics
• Flash guide number- indicates how powerful
the flash is.
– A GN of 40 is adequate for dental
p...
Synchronization
• The duration of the electronic flash is very
short, often less than 1/1000 second, and it
goes off insta...
• If your shutter is adjusted to higher speeds as
prescribed by the manufacturer, you may end up
with partially lit photog...
Red-Eye
• We've
all
see
photographs where
the people in the
picture have spooky
red eyes. Where do
the red eyes come
from?...
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 t...
Eliminating Red-eye
• Many cameras have a "red eye reduction "
feature. In these cameras, the flash goes off
twice -- once...
• Red-eye normally occurs when the angle of the
light, striking the subject and being reflected off
o
the camera is 2.5 or...
www.indiandentalacademy.com
Leader in continuing dental education

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

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
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Clinical photography 01 /certified fixed orthodontic courses by Indian dental academy

  1. 1. CLINICAL PHOTOGRAPHY www.indiandentalacademy.com
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  6. 6. • In skilful hands, a camera can transform an ordinary scene into an image of exceptional beauty. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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 www.indiandentalacademy.com
  10. 10. • Teaching • Publication / Clinical research • Communication with colleagues • Record keeping • Legal protection www.indiandentalacademy.com
  11. 11. CAMER A www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  13. 13. • The inside of the camera must be completely dark , so that the rays of light reach the film only through the aperture. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  15. 15. www.indiandentalacademy.com
  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’. www.indiandentalacademy.com
  17. 17. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  19. 19. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  21. 21. TYPES OF CAMERAS www.indiandentalacademy.com
  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) www.indiandentalacademy.com
  23. 23. SINGLE LENS REFLEX www.indiandentalacademy.com
  24. 24. www.indiandentalacademy.com
  25. 25. TWIN LENS REFLEX www.indiandentalacademy.com
  26. 26. www.indiandentalacademy.com
  27. 27. COMPONENTS OF A 35mm SLR CAMERA Hot Shoe For Flash www.indiandentalacademy.com
  28. 28. www.indiandentalacademy.com
  29. 29. LENS www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  34. 34. CONVERGING OR CONVEX LENS DIVERGING OR CONCAVE LENS www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  36. 36. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  38. 38. FOCAL POINT www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  41. 41. FOCAL LENGTH www.indiandentalacademy.com
  42. 42. • A long-focus lens forms a larger image of a distant object, while a short-focus lens forms a small image. www.indiandentalacademy.com
  43. 43. www.indiandentalacademy.com
  44. 44. • The closer that you move an object to the lens, the larger it will appear on the film or photograph. www.indiandentalacademy.com
  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 . www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  47. 47. www.indiandentalacademy.com
  48. 48. TYPES OF LENSES www.indiandentalacademy.com
  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 www.indiandentalacademy.com
  50. 50. www.indiandentalacademy.com
  51. 51. www.indiandentalacademy.com
  52. 52. Wide-Angle Lens – Includes focal lengths ranging from around 15mm through 35mm – Particularly well suited to landscapes and architectural photography www.indiandentalacademy.com
  53. 53. www.indiandentalacademy.com
  54. 54. www.indiandentalacademy.com
  55. 55. Normal / Standard lens – 50mm lens – Suitable for all general photography – Usually are the cheapest available for cameras www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  57. 57. www.indiandentalacademy.com
  58. 58. www.indiandentalacademy.com
  59. 59. • In addition, a short telephoto lens is considered ideal by many photographers for portrait photography. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  61. 61. 50mm 120mm www.indiandentalacademy.com 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). www.indiandentalacademy.com
  63. 63. • Macro lenses offer a stepless range of magnifications and shooting distances. • They make good portrait lenses. www.indiandentalacademy.com
  64. 64. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  66. 66. www.indiandentalacademy.com
  67. 67. www.indiandentalacademy.com
  68. 68. www.indiandentalacademy.com
  69. 69. www.indiandentalacademy.com
  70. 70. www.indiandentalacademy.com
  71. 71. www.indiandentalacademy.com
  72. 72. www.indiandentalacademy.com
  73. 73. www.indiandentalacademy.com
  74. 74. www.indiandentalacademy.com
  75. 75. www.indiandentalacademy.com
  76. 76. www.indiandentalacademy.com
  77. 77. www.indiandentalacademy.com
  78. 78. www.indiandentalacademy.com
  79. 79. www.indiandentalacademy.com
  80. 80. www.indiandentalacademy.com
  81. 81. www.indiandentalacademy.com
  82. 82. www.indiandentalacademy.com
  83. 83. www.indiandentalacademy.com
  84. 84. www.indiandentalacademy.com
  85. 85. www.indiandentalacademy.com
  86. 86. www.indiandentalacademy.com
  87. 87. www.indiandentalacademy.com
  88. 88. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  90. 90. SHUTTER SPEED www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  94. 94. 1/30 1/1000 www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  96. 96. MECHANISM www.indiandentalacademy.com
  97. 97. www.indiandentalacademy.com
  98. 98. www.indiandentalacademy.com
  99. 99. • Usually, in Dental Photography, we have standard situations which are static. Therefore, the shutter speeds are also standard viz. 1/60 www.indiandentalacademy.com
  100. 100. APERTURE www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  102. 102. • The aperture does this either by opening or closing , and allowing more or less light to pass through. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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 www.indiandentalacademy.com
  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 www.indiandentalacademy.com
  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 www.indiandentalacademy.com
  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 www.indiandentalacademy.com 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 www.indiandentalacademy.com 50mm
  109. 109. • The 200mm is longer than the 50mm lens. • Therefore the light has to travel further to reach the film. 200mm www.indiandentalacademy.com 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 www.indiandentalacademy.com 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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  113. 113. FILM www.indiandentalacademy.com
  114. 114. Types • Black & White • Colour • Colour reversal (for slides) • Also, Instant film (Polaroid) www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  118. 118. • The film speeds available range from ISO 25 to ISO 3200. • ISO 25 being the slowest and ISO 3200 being the fastest. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  122. 122. www.indiandentalacademy.com
  123. 123. www.indiandentalacademy.com
  124. 124. www.indiandentalacademy.com
  125. 125. EXPOSURE www.indiandentalacademy.com
  126. 126. • Exposure is the total amount of light reaching the film in the camera. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  128. 128. • The three factors that affect the exposure are – Aperture setting (smaller number) – Shutter speed (smaller number) – Film speed (larger number) www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  132. 132. DEPTH OF FIELD www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  134. 134. www.indiandentalacademy.com
  135. 135. Factors affecting DOF • Aperture size • Focal length of the lens • Distance of the subject from the camera www.indiandentalacademy.com
  136. 136. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  138. 138. 1.4 4 22 8 www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  140. 140. FLASH & LIGHTING www.indiandentalacademy.com
  141. 141. • The two most important sources of light are – Natural – Artificial / Flash www.indiandentalacademy.com
  142. 142. •Using different combinations of the two can enable the photographer to obtain a wide variety of results, often with dramatic effects www.indiandentalacademy.com
  143. 143. www.indiandentalacademy.com
  144. 144. Hard Light Soft Light www.indiandentalacademy.com
  145. 145. • In dental photography, the flash gun is always employed, irrespective of the type i.e. I/O or E/O photography. www.indiandentalacademy.com
  146. 146. TYPES OF FLASHES www.indiandentalacademy.com
  147. 147. Built-in flash www.indiandentalacademy.com
  148. 148. Dedicated point flash www.indiandentalacademy.com
  149. 149. Ring flash www.indiandentalacademy.com
  150. 150. www.indiandentalacademy.com
  151. 151. Ring + Point Combo www.indiandentalacademy.com
  152. 152. www.indiandentalacademy.com
  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 www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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? www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  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. www.indiandentalacademy.com
  160. 160. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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