forensic photography

PHOTOGRAPHY

the art and science of capturing the image of a certain event in time and recording it in a film or a digital medium using a camera

who captured the first photography

Joseph Nicephore Niepce in France It shows the roof of a building lit by the sun

when was the first photograph

The first permanent photograph was captured in 1826 or 1827

Photography

Literal definition

The word photography is a derivative of two Greek words phos which means "light" and graphia meaning "write". Therefore, photography best translates to "write with light."

Photography Modern definition:

Photography is an art or science which deals with the reproduction of images through the action of light, upon sensitized materials, with the aid of a camera and its accessories, and the chemical processes Involved therein.

photography Technical/Legal definition:

Modern photography may be defined as any means for the chemical, thermal, electrical or electronic recording of the images of ble light and infrared rad by some type of radiant energy, including gamma rdronic recor ultra-violet rays, visible light and infrared rays. This definition is broad enough to include not only the raventional methods of photography but almost any new process that may be developed.

Police Photography

an art or science which deals with the study of the principles of photography, the preparation of photographic evidence, and its application to police work

Forensic Photography

the art or science of photographically documenting a crime scene and evidence for laboratory examination and analysis for purposes of court trial.

The Basic Components of Photography

1. Light-the days of creation

2. Equipment (1700)

3.Chemicals (1726-1777)

In 1800 thomas Wedgewood and Humphry Davy photograms.

Light sensitivity of silver nitratproduced photolande solution was discovered and investigated.

The portable camera obscura

(Latin for dark chamber) was used by artist or painters to get accurate perspective of natural scene and scale of their subjects.

Light-the days of creation

In the beginning, God created the heavens and the earth. Now the earth was formless and empty. darkness was over the surface of the deep, and the spirit of God was hovering over the waters.

1850

The year when photography was already well-developed. It was used as an art concerned with landscape, portraiture and architectural presentation

1835

The year when colored filmis, sensitized materials and different brands of cameras came in different types and model sold in the market.

Electromagnetic Spectrum

A colored band that is formed when light is allowed to pass through a prism

It includes different energies such as a lowed to as thous ultraviolet rays, visible light. infrared rays, heat rays, Hertzion waves, and the alternating current

Four Photographic Rays of Modern Photography

1. X-rays-01 to 30 mm

2. Ultra-violet rays 30 to 400 n

3. Visible Light-400 to 700 nn

4. Infra-red rays-700 to 1000+ inn

General Types of Light

1. Visible Light

2. Invisible Light

Visible Light

- lights with a wavelength of 400 to 700 nm

Invisible Light

lights with a shorter or longer wavelength

luminescence

The final effect a radiant energy may have on an object is to be converted to another wavelength. This conversion is known as

Two types of luminescence

Fluorescence

Phosphorescence

Fluorescence

is the ability of an object to convert one wavelength to another as long as the active energy source is irradiating the object.

Phosphorescence

the object not only converts the wavelength while being irradiated but continuous to reflect the new wavelengths for a period of time after the energy source is removed.

Irregular or diffused reflection

occurs when light hits a rough or uneven but glossy object.

Refraction

the bending of light when passing from one medium to another

Diffraction

the bending of light when it hits a sharp edge of an opaque object.

Translucent objects

allows light to pass, however diffuse it sufficiently that objects on the other side may not be clearly distinguished. In some cases, the objects on the other side may be recognizable but sharp detail and outline are obscured.

Opaque objects

so greatly diffuse the light that recognizing the object on the other side is very difficult if not impossible.

Intensity

it refers to the strength of light which varies according to the output of the light source and the distance from the source.

white light

When the wavelengths from 400 to 700 nanometers are present in nearly equal amounts, our eyes perceive what light?

white light

When blue, green, and red overlap in proper ratios, they produce ?

White and black

The presence of all colors (all light).

The absence of light (and therefore all colors).

Bending of Light

1.Reflection

a. Regular reflection

b. Irregular or diffused reflection

2. Refraction

3. Diffraction

Kinds of object as to how they behave to light

Transparent objects

Translucent objects

Opaque objects

Qualities of Light

1. intensity

2. Direction

3. Color

Direction

when there is a single source, the direction is clearly defined. Where there are multiple sources, or light is diffused as on cloudy day, the direction ules evident or totally absent

Color

Light varies in color depending upon its source and the substance through which it passes. Natural sunlight has a different color mixture from incandescent lighting or electronic flash and the color of sunlight itself varies depending upon atmospheric condition and time of the day. The following are the characteristics of color hus, saturation and brightness

source of sunlight

Sources of Light

Artificial light source -

Continuous radiation

are those that can give illumination continuously. The common light source of this kind is the fluorescent lamp, incandescent lamps, carbon arc lamp, photoflood lamp, gas lamp, etc.

short duration (Flash unit)

A flash unit gives a brief flash of light produced by a burning metallic wire (flash bulb) or an electrical discharge through a gas-filled tube (electronic flash). At this time, the flash bulb is no longer available in the market but the electronic flash remains very popular. The electronic flash offers a great light output in a compact, lightweight and economical form. It does not have the effect of heat and glare during setup that are common with continuous light sources. Because it is battery-powered, it is most convenient for field work where AC current is not available. Like any other artificial source, flash units allow the photographer to control the direction, quality and intensity of light to achieve the desired result.

Electromagnetic Spectrum

➤ A colored band that is formed when light is allowed to pass through a prism

➤ It includes different energies such as cosmic rays, gomma rays, x-rays, ultra-violet rays, visible light, infrared rays, heat rays, Hertzian waves, and the alternating current.

VISIBLE LIGHT

Light Rays with wavelength of 400 to 700 nn

Human eye is capable of perceiving

INVISIBLE LIGHT

Those with shorter or longer wavelength that the visible light

Human eye is not capable of perceiving.

Production of Colors

Colors can be produced through several physical phenomena. Understanding these methods helps us evaluate and control color quality:

Absorption:

Objects appear colored because they absorb different amounts of light at different wavelengths.

The colors we see are the wavelengths that are reflected, not absorbed.

Scattering:

The blue color of the sky is a result of light scattering in the atmosphere.

Atmospheric gases scatter shorter wavelengths (blue) more than longer wavelengths (red), making the sky appear blue when clear and whiter when hazy.

Interference:

Thin films (like soap bubbles or oil on water) produce color through interference.

Light reflected from the top and bottom surfaces of a film can interfere with each other, sometimes shifting phases and creating vibrant color patterns (e.g., Newton's rings).

Fluorescence:

Certain materials absorb light at one wavelength and re-emit it at a different wavelength.

This re-emission of light creates a fluorescent effect.

Dispersion:

Dispersion occurs because different wavelengths of light bend by different amounts when passing through a medium.

This effect is seen in prisms, where white light is separated into its component colors, forming a rainbow.

Production of Colors

Dispersion

:Fluorescence

:Interference

:Scattering

:Absorption: