Forensic Photography II Flashcards
The amount of light reflected by the performer and the background.
Intensity
Also known as the temperature of the light reflected by the performer and the background.
Color
Determines the length and location of the shadows cast by the
performer and the three-dimensional props around him.
Direction
It is not something we can measure. It is, instead, something we describe based upon
visual perception; light is either soft or hard. Also, may referred to as the Hardness of the light.
Quality
Refers to the difference in brightness between the brightest and darkest parts of the image which is
the contrast between highlight and shadow areas. Highlights are the brightest parts of the image and shadows
are the darker regions of an image.
Contrast
It is when the sun sets, day turns into night and it becomes dark.
Moon and Stars
The most popular and mostly used light source of photographers. It is free and no need to be transported.
But it is not always there where we want it. It is uncontrollable but can be controlled using the camera controls (shutter
speed & aperture opening).
Sunlight
This is the direct sunlight striking the subject. It is the brightest of all, it is highly directional, images taken with distinct sun is characterized by extreme highlights and deep shadows and it provides the highest contrast in a picture.
Bright sunlight or Distinct sun
When the sun is covered by thin clouds but still clearly visible and it is illuminating your subject, it produces soft shadows and moderate highlight and contrast is also moderate, while
rays are directional.
Hazy Sunlight
Objects in open space cast no shadow
Dull Sunlight or Cloudy
Sun is bright but not visible, light is soft and not directional,
Overcast Sky or Cloudy Bright
This is practically the same as overcast sky but generally darker and light is dull. It provides very poor contrast and static cloud is so thick where one cannot tell the overhead position of the sun.
Heavy Overcast or Cloudy Dull
Distinct sun is used as ______ lighting when it comes from behind the photographer
Front Lighting
This type of lighting happens mostly in the morning and afternoon when the sunlight hits the subject from either the right or left flank of the photographer.
Side Lighting
This type of lighting happens when the sun strikes the subject from behind
Back Lighting
This normally occurs at noontime where sun is directly above your subject.
Overhead Lighting
Closest star on earth (4 light-years)
Centauri Proxima
Primary application of forensic light source for enhancing the detection of latent fingerprint
Latent fingerprint detection
The dried body fluids will actually glow under the light source of illumination
Bodily fluids
Two light illumination method can be employed. first, oblique or parallel lighting of a surface. Second, hair and fibers will also glow under UV.
Hair and fibers
A tunable forensic light source can be used to identify light variations in ink type by viewing ink responses as the color of the light is turned through the visible and infrared regions.
Questioned Document
SPEED OF LIGHT
299,792,458 meters per second
Refers to some units are portable battery operated and are easily carried and can meet the rugged and rigorous demand for Field work
UV Lamp
Refers to Light amplification through simulated emission of radiation. They would fluoresce or could be made to stand out in sharp contrast from their background.
LASER
Refers to far more expensive alternative to forensic laser. It uses a variety of band pass filters to provide a high intensity beam of non-coherent light.
Alternative Light Source
Refers to a wide variety of relatively inexpensive light sources which used filtered white light.
Forensic light source
Refers to a pair of carbon rods connected in series with a resistance across directly current.
Carbon arc
Refers to a conducting filament enclosed by a glass bulb heated by the electric current until emits light.
Incandescent
Refers to a lamps that can be placed up very high producing deep shadows underneath protruding surfaces. These can be placed to shine from below giving mysterious and strange effects of frights to observers of the picture
Photoflood lamps
Refers to illumination in an electric discharge lamp of the mercury-vapor type
Fluorescent Lamps
Refers to light that produces by the rapid burning of metal wire, foil, or primer powders.
Chemical flash lamp
This is consisting of a slender glass tube filled with a gas (xenon), a high voltage electrical discharge is passed through coiled tube, causing the gas to glow.
Electronic flash lamp
It occurs whenever an object changes the direction of a light wave but does not allow the wave to pass through it.
Reflection
It is the change in direction of a wave due to a change in its speed.
Refraction
It is described as the apparent bending of waves around small obstacles and the spreading out
of waves past small openings.
Diffraction
It allows sufficient visible light to pass through them that the object on the other side may be
clearly seen
Transparent objects
It allows light to pass, however diffuse it sufficiently that objects on the other side may not be clearly distinguished
Translucent objects
It is so greatly diffuse the light that recognizing the object on the other side is very difficult if not impossible
Opaque objects
electromagnetic energy having a wavelength that ranges between 10-30 millimicrons
X-ray
divided into the near and far ultraviolet and ranges from about 200-400 millimicrons wavelength.
It is used to photograph fingerprints on multi – colored background, documents that are altered chemically or over writings and detection of secret writings.
Ultraviolet light
Shortest wavelength
Used in recording or photographing objects hidden by opaque mediums.
Gamma rays
high energy charged particles, originating in outer space, that travel at nearly the speed of light and strike the Earth from all directions.
Cosmic rays
. It is an invisible rays and it is only detected by the human skin as heat.
• Used in taking photographs of obliterated writing, burnt or dirty documents. Also known as
“Blackout photography”.
Infrared light
These light waves have the longest wavelength of all lights.
Used for communicating through the modification and amplification of sound waves.
Radio waves
excite the water molecules in food, heat them up, and pass the heat throughout the
food.
It can harm the body because it can heat the water molecules in deep tissues.
Microwaves
An electromagnetic wave produced by the oscillation of electricity in a conductor (as a radio antenna) and of a length ranging from a few millimeters to many kilometers.
Hertzian waves
