Reflections

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Reflections
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• A Reflection is light striking an object and
  bouncing of it. Reflection is what makes vision
  possible.
• We do not see objects we only see the light
  reflected of them. Since most objects produce no
  light, their visibility depends entirely on light
  reflected of them.

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Types of reflection

• Light can reflect from a subject as either a-
• Diffuse reflection
• Direct reflection
• Glare (Polarised Light)

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Diffuse Reflections
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What are Diffuse Reflections ?

• When a light source reflects of a matt surface
  the light scatters and breaks up the original
  light beam, reflecting it evenly in all
  directions. If a light source reflects of an
  object in all different directions, it is called
  a diffuse reflection. For example, room light may
  reflect of a sheet of newspaper that you may be
  reading.

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Rule 1

• Diffuse reflections are seen with the same
  brightness level regardless of the angle from
  which they are viewed and regardless of what
  angle we place the light source.

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• This means that regardless of where we place our
  camera (viewpoint), the light will always evenly
  reflect of the diffuse surface.

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• A second characteristic is that light shining
  from any angle onto a diffuse surface will also
  reflect of it with exactly the same brightness.
  Neither the angle of illumination nor the angle
  of view affects how bright the subject is in a
  photograph.

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Rule 2

• Diffuse surfaces appear the same regardless of
  whether we use a large light source or a small
  light source.

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• From earlier experience we have determined that a
  small light source causes hard shadows and a
  large light source causes soft shadows. So how
  does it affect diffuse surfaces?

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• The contrast of the light source does not affect
  the appearance of a diffuse reflection.
• If you were to place some coins on top of a
  newspaper and make two photographs one with a
  large light source and one with a small light
  source - you will find that the size of the light
  source will only affect the coins and not the
  newspaper.

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Direct Reflections
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• Because light travels in straight lines, it
  always reflects off a surface at the same angle
  at which it strikes it.
• For instance, we know that light rays striking a
  surface from the right will be reflected to the
  left. Light coming from above and behind the
  subject will be reflected up and to the front,
  sometimes directly into the lens of our camera.

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Rule 3

• The angle of incidence equals the angle of
  reflectance.

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• Shiny surfaces need more care than usual in a
  studio. They are not necessarily problem objects
  but they do posses two qualities that have an
  important veering on the lighting and
  construction of the set. They act like mirrors
  that pick up images of their surroundings which
  can include the camera and other elements outside
  the set, and they have a tendency to create high
  contrast by picking up reflections of the lights.

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• Brass, polished metal, and lacquer are typical of
  objects that are inherently reflective, while
  liquids can turn normally matt surfaces shiny.
• The basic principle of photographing such
  surfaces is that the reflection itself is a part
  of the subject. In other words, the surroundings
  that will be reflected in the surface must be
  anticipated and controlled.

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• Fortunately in a studio this control is possible.
  If the surface is simple, such as flat, it will
  reflect only a limited part of its surroundings
  and this can be controlled, whether by altering
  the angle of the object or by rearranging the
  surroundings.

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• If the surface is convex or concave such as a
  bowl or a spoon or the glass of an electric light
  bulb, the reflection is likely to cover a wide
  angle, and this will probably include the camera
  and nearby photographic equipment, none of which
  is likely to be wanted in the picture. The light
  source will also probably be included.

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Lighting

• Chrome Part One

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• FLAT METAL.
• A small piece of flat metal has only a small
  family of angles from which direct reflections
  can be produced.
• This makes such a piece of metal the simplest
  example we can use to describe the general
  principle of lighting any metal.

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• One of the first decisions that we have to make
  when we photograph a piece of metal is how bright
  we want it to be.
• Do we want it to be bright, dark, or something
  in between? The answer to this question
  determines the lighting.

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• If we want the metal to appear bright in the
  photograph we must make sure our light source
  fills the family of angles that produces direct
  reflection.
• If on the other hand we want the metal to be dark
  in the picture, we put the light anywhere else.
• The first step in lighting metal is to find that
  family of angles.

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• Solution.
• 1. Position a white target where you think the
  family of angles will be. This white target can
  be any convenient large surface. The easiest will
  be whatever large piece of diffusion material you
  might eventually use to light the metal. The less
  sure you are of where the angles are, the bigger
  the surface needs to be.

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• 2. Place a test light at the camera lens. Aim the
  test light at the point on the metal surface that
  is nearest to the camera. The light will reflect
  off the metal and onto the test surface. This
  will be the point at which the beam marks the
  near limit of the family of angles. Use a piece
  of tape to mark the spot.

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• Similarly, mark as many points as you need to see
  where the family of angles lies. The shape of the
  metal subject determines the necessary number of
  points.

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• This exercise will make it easy to find the
  source of glare or hot spots on any type of
  subject from now on.

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• Keeping the Metal Bright.
• Since photographers usually choose to make the
  metal in their picture look bright, we will deal
  with that case first. If we assume that we want
  the entire surface of the metal to photograph
  brightly, we then need a light source that at
  least fills the family of angles that produces
  direct reflection.

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• When we use a light this size, it will produce
  direct reflections over the entire surface of the
  subject. These reflections make the subject
  bright in the picture. It is worth noting that
  because polished metal produces almost no diffuse
  reflection, light coming from any other angle
  will have practically no effect on the metal,
  regardless of how bright it is or how long the
  exposure.

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• It is also important to realize that a light that
  just fills the family of angles is the minimum
  light size we can use.

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• Keeping the Metal Dark.
• In the previous section we talked about how to
  photograph the metal to appear bright. Now we
  will re-light the scene to keep the metal as dark
  as we can. All we have to do is to light the
  metal from any direction other than from within
  the family of angles that produces direct
  reflection. One simple way to do this is to put
  the light near the camera.

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• Combination Lighting.
• Sometimes we never use the bright metal or the
  dark metal lighting techniques by themselves.
  More often we prefer a combination of the two, a
  compromise between the extremes. We can decide
  exactly where we want to place the metal on the
  gray scale. The precise tone of the metal is
  fully controllable but then a decision is
  required as to what tone the background is
  required to be.

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• Using one light in this manner becomes a
  compromise as to which tone has precedence - the
  background or the metal. This often requires two
  lights. Using two lights gives infinite control
  of the relative brightness of the metal and the
  background.

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