FORENSIC PHOTOGRAPHY 2 Flashcards
is a radiant electromagnetic energy that can be seen by the naked eye. It excites the retina of the eye and makes things visible.
Light
those that can be detected by our naked eye
Visible –
these are the radiations, which are either too short or too long in wavelength to excite the retina of the eye.
Invisible
This refers to the speed of light as it travels. (Usually light travels 186, 000 miles per second)
The Velocity of travel
This is the distance between two successive crests since light travels in wave motion.
The Wavelengths
This refers to the quantity or the number of waves that light creates as it travels.
The Frequency or the number of vibration of the wavelength
Refers to rays having a wavelength of 1 to 30 millimicrons. Hallow solid objects as seen by the naked eyes can be penetrated by x – rays. This is being used to produce shadow photogtaphs of internal structures of solid objects.
X – Ray Radiation
It is a ray having a wavelength of 30 to 40 millimicrons. These rays give up energy in the form of visible light that gives “fluorescent effect” to the object. It can be use in photographing fingerprints on multi – colored backgrounds, in documents that are altered chemically as well as in the detection of secret writings.
Ultra Violet Rays (UV)
It is otherwise known as “black light”.
Ultra Violet Rays (UV)
The wavelength of visible light is from how many miliimicrons which produces white light.
400 to 700 millimicrons,
Isaac Newton in 1666, state that the light which man sees as white is actually a mixture of all colors of the spectrum. He discovered this, when a beam of light passed through a glass prism and produces the rainbow array of hues of the visible spectrum. With this, we can say that white light means presence of all colors of light, and black means absence of all of colors light.
in 1666, state that the light which man sees as white is actually a mixture of all colors of the spectrum. He discovered this, when a beam of light passed through a glass prism and produces the rainbow array of hues of the visible spectrum. With this, we can say that white light means presence of all colors of light, and black means absence of all of colors light.
Isaac Newton
is actually a mixture of seven colors, namely red, orange, yellow, green, blue, indigo, and violet.
White light
with 400 to 500 millimicrons, it has the shortest wavelength
Blue –
with 500 to 600 millimicrons, it has a medium wavelength
green –
with 600 to 700 millimicrons, it has the longest wavelength
red
A combination of blue and green colors
Cyan
A combination of green and red colors
Yellow
A combination of red and blue colors
Magenta
It is a ray having a wavelength of 700 to 100 millimicrons. means below the red. Even though our eyes cannot see the IR, we have a sensor for it, “our skin”.
Infra red Rays (IR)
comes to the existence without the intervention of man,
Natural
It usually refers to daylight.
Natural Lights
is considered as the source of all daylight. Daylight can be classified according to their intensity.
Sun
simply means the amount or the quantity of light that are present in a scene.
Intensity
Objects in open space, cast a deep, strong and uniform shadow.
Bright Sunlight
Object in open space cast a transparent shadow. In hazy sunlight, the clouds partially cover the sun.
hazy Sunlight
Objects in open space cast no shadow. At this time, the sun is totally covered by the clouds.
Dull Sunlight
Almost all ——– light sources are possible to be used in photographing an object. But most preferred those lights that are incandescent.
Artificial Light
means, light are produced by means of heat. In photography, incandescent is usually known as ——
Incandescent
tungsten light.
It is also known as reflectorized light or spot light. This lamp used reflector to focus the light, to the object being photographed.
b. Flash Bulb
photoflood Lamp
These are chemical lamps for they generated light through the rapid combustion of metal in oxygen. can be ignited by means of a flashgun and can only be used once as the is busted when fired electrically.
Flash Bulb
These are tube lamps wherein the walls are coated with materials that are capable of fluorescence. These are commonly used by anybody but not merely in photography for the light it produces are not incandescent.
Fluorescent Light
It is a special type of lamp that is capable of producing infra- red radiation. This type of bulb is useful in photographing object at dark places.
Infra – Red Lamp
Produces light by instantaneous electrical discharge between two electrodes in a glass filled glass bulb.It has the capability to arrest or stopped objects, or subjects in fast motion.
Electronic flash
It is a gas lamp burning disulfide vapor in oxygen or in nitric oxide. Its bulb is made up of a glass transparent to ultra violet light, and such bulb is common to all people as “black light”.
Ultra Violet Lamp
light rays are the one that affects the eyes. The object is seen as white when all of the various wavelength of the visible light are reflected.
Reflected -
– when there was no reflection from the subject and all of the various wavelength of the visible rays are absorbed, this will produce black, which means absence of all colors.
Absorbed
– when the rays of light pass through a transparent material, such rays will be transmitted on the other side.
Transmitted
is the process of bending the rays of light as it strikes a transparent material. Best example of this is when rays of light passed through the water.
Refraction
on the other hand occurs when the rays of light reach an opaque material. This usually happens when a light strikes the sharp edges of a knife.
Diffraction
There are two kinds of sensitized material
Film
Photographic paper
that produces the negative after chemical development and the
the Film
that produces a photograph or positive print after printing and chemical development.
Photographic paper
is a part of the sensitized material that is actually sensitive to light.
Emulsion
are consists of a flexible transparent base, that is coated with a thin layer of light – sensitive emulsion
Photographic Films
are consists of a flexible transparent base, that is coated with a thin layer of light – sensitive emulsion
Photographic Films
is consists of silver halide particles suspended in an animal gelatin and coated by a celluloid material to prevent abrasion.
are light sensitive compound. They darken when exposed to light.
The emulsion
is a strip or sheet of transparent plastic film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The size and other characteristics of the crystals determine the sensitivity contrast and resolution of the film
Photographic film
is a strip or sheet of transparent plastic film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The size and other characteristics of the crystals determine the sensitivity contrast and resolution of the film
Photographic film
It is cellulose tape or plate where silver salts are suspended capable of recording light.
Its primary function is to record the image that is focused upon it by the lens of the camera.
film
called panchromatic films to record the entire visible spectrum. Some films are orthochromatic, recording visible light wavelengths.
black and white film
This refers to the characteristics of the film to response into the different wavelength of light source. This is considered as the most important characteristics of the film.
The Spectral Sensitivity
sensitive to ultra violet rays and blue color
Blue Sensitive (orthonon) –
sensitive to ultra violet rays, blue and green, except in red
Orthochromatic
– sensitive to ultra – violet rays, blue green and red and to all colors except in infra – red.
Panchromatic
Three Classes of Panchromatic Film
fine grain
it permits shorts exposure under average lighting condition and has the advantage of fine grain structures.
Fine Grain –
it is low in speed and high in contrast
Process –
this is intended for photographing an object or subject under adverse lighting condition.
High Speed –
sensitive to ultra violet rays and infra – red rays
Infra – Red –
is the measure of the film’s sensitivity to light. The higher the sensitivity of the film, the higher the film speed rating number.
the film speed
ASA means
which became ANSI in 1970.
American Standards Association”,
or “American national Standards Institute”
Types of Speed Rating
asa rating
din rating
iso rating
DIN Rating – DIN stands
for This is expressed in Logarithmic value such as: DIN 12, 15, 18, 21, 24, 27, 30, 33 degrees, etc. In DIN rating, each increased of three times towards the higher speed rating, doubles the sensitivity of the film.
“Deutches Institute Fur Normung or Deutches Industri Normen”.
DIN stands
“Deutches Institute Fur Normung or Deutches Industri Normen”.
for This is expressed in Logarithmic value such as: DIN 12, 15, 18, 21, 24, 27, 30, 33 degrees, etc.
each increased of three times towards the higher speed rating, doubles the sensitivity of the film.
DIN Rating
This is a group of standard – setting bodies from many countries.
ISO Rating –
ISO is short for
“International Standard Organization”.
Sensitized paper serves as the permanent place for the photographic image after chemical development. It is the material or the paper used for producing positive print or photographs.
photograpic paper
is also coated with light sensitive emulsion, not in a transparent material but in something opaque such as paper.
photographic paper
These photographic papers are widely used for projection printing or enlarging process, wherein the image in the negative are projected or enlarge with the aid of an “enlarger”
t is considered as the best photographic paper for police investigative work.
silver bromide emulsion
Its sensitivity to light is low and commonly used in contact printing, wherein a photographic image from the negative is transferred to the photographic paper through a direct contact with each other (negative and photographic paper) under a certain amount of light
Silver Chloride Solution
– the photographic paper that contains both silver chloride and bromide is———— . With this, the sensitivity of this paper to light could either be slow or fast. Meaning, it has a slow emulsion for contact printing, and a fast emulsion provided for projection printing.
Silver Chlorobromide Papers
this prevent the paper from being scratched.
Protective Coating –
this is the part of the paper that does the real work. It contains the silver chlorides or bromides suspended in gelatin. These react with light to create a latent image, which cannot be seen until the development process has taken place. Paper is less sensitive than film, it usually required several or tens of seconds of light exposure to create an image.
Emulsion –
this layer stops the emulsion from soaking into the fibers of the paper. This makes the processing, washing and drying quicker and prevents the paper from getting soggy and falling apart.
Pigmented Polythene –
– good quality paper with anti – curl agent
Paper
exposure of film to cause an image after development is not just a matter of how bright the light on the film, but as well as how long it is allowed to fall on the film
The Shutter –
exposure of film to cause an image after development is not just a matter of how bright the light on the film, but as well as how long it is allowed to fall on the film
The Shutter –
It is defined as a contraption or device that used to black the path of light passing through the lens and exposing the sensitized material in a pre – determined interval of time.
Shutter?
a shutter that is located in the lens (usually between the elements of the lens). It is made up of metal leaves and its action from the center toward the side, then close back to the center
Central Shutter
It is usually made up of cloth curtain but also available in metal. Some focal plane shutter moves vertically to make an opening, while other camera models use horizontally moving shutter.
- Focal Plane Shutter –
is usually located on top of the camera. This will allow you to change the shutter speed, to control the length of time the film will be exposed to the light that pass through the diaphragm opening.
A shutter speed
it continuously keeps the shutter to be in open position while still pressing the shutter release button.
B – Setting –
it keeps the shutter in an open position in one press, and close it back by another click
T – Setting -
it is located at the back of the camera. Its function is to hold firmly the sensitized material in its place during exposure to prevent the formation of multiple or blurred image of the subject. It is usually consist of cavity for a film cartridge and a film take up spool.
Holder of Sensitized Material/Film Holder –
Its function is to hold firmly the sensitized material in its place during exposure to prevent the formation of multiple or blurred image of the subject. It is usually consist of cavity for a film cartridge and a film take up spool.
Holder of Sensitized Material/Film Holder
the viewfinder of the camera determines the entire scene coverage that will be recorded on the film inside the camera during the exposure.
View Finder or Viewing System –
, is to transfer the exposed film on the take up spool, and advance the remaining unexposed film behind the lens and prepare it for another exposure.
Film Advancer
– the light gathering power of the lens is determine by the area of its aperture or opening. Control over the lens aperture can be obtained by selecting the desired f – numbers, engraved on the aperture ring of the lens.
Lens Aperture
controls the speed of opening and closing of the shutter, to regulate the quantity of light that will expose the sensitized material inside the camera.
Shutter Speed Selector –
– the focusing system of the camera provides sharpness and clearness to the objects being photograph.
Focusing Mechanism
– are the most popular and useful camera support for general photography.
Tripods
comes in different lengths and allowed you to fire the camera from a distance.
Cable Release
– this could either be a flash bulb or electronic flash, which is synchronized to the action of the shutter. This is very effective especially when there’s no enough light for the object being photograph.
Flash Units
– a source of artificial light that occurs through burning certain metals in an atmosphere of oxygen.
The Flash Bulbs
– involves the process of producing light by passing an electrical current through a glass bulb containing a gas.
Electronic Flash
– it is a device used in determining the intensity of light that strike the subject and affect the film.
Light Meter / Exposure Meter
– the reflected light from the shadow as seen by the naked eye is estimated and calculated by direct observation of the photographer.
Extinction Meter
– the most dependable device for measuring the brightness of light. A device is being pointed toward the subject to be photographed, and convert the collected light into electric energy that makes the needle of the meter to move across its scale.
- Photo Electric Meter
usually use in Close – up Photography. this are just light tight spacers that fit between the camera body and the lens.
Extension Tubes –
– a transparent medium that transmits and absorbs different wavelength of light passing through it. They are usually made out of glass or gelatin material placed in front or behind the camera lens.
Filters
– a device used to hold firmly the camera so as to prevent the vibration of movement during the period of exposure.
Camera Grip
helps prevent extraneous light from striking the front element of the lens that causes flare.
Lens Hood
2 kinds of shutter
central shutter
focal plane shutter
