Forensic Photography: An Overview

• Photography is a key branch of forensic science with four components: light, sensitized material, mechanics, and chemicals.
• Photography is an art/science reproducing images via light action via lenses, cameras, and accessories.
• Photography comes from the Greek words "Phos" meaning light and "Graphia"/"Graphos" meaning to draw or write.
• Photography gained precedence over Heliography, Photogeny, and Daguerreotypy.

Photography vs. Picture vs. Image

• Photograph/Photo refers to the mechanical and chemical result of using a camera.
• Picture is a generic term for all kinds of formed images.
• Image refers to visual objects created or modified on a computer.

Forensic Photography Explained

• Forensic Photography, also called Forensic Imaging or Crime Photography, accurately reproduces crime or accident scenes for court or investigations.
• Crime scene photography is a primary documentation component, providing systematic visual records of undisturbed scenes.
• Forensic Photography involves correct lighting, accurate lens angling, and multiple viewpoints.
• Scales or known-size objects record item dimensions in forensic photos.

Purpose and Professionals

• Forensic Photography records scenes, evidence, and provides visuals: for investigators, analysis, and court.
• A forensic photographer, also known as a crime scene or evidence photographer, captures exact, detailed, objective photos for legal use.

Importance and Implications

• Crime Scene Photography is needed in court.
• Altered crime scenes are not restorable to the original condition.
• Crime scene aspects can later become important to a case.
• Photographing a crime scene should be the first step in any investigation, done completely and accurately before anything is disturbed.
• Post-removal photographs also must be taken.

Crime Scene Reconstruction

• Photographs help specialists reconstruct the crime scene.
• Photographs help the prosecutor, and can be coordinated with sketches/drawings.

Mugshots and Rogues Gallery

• Mugshots are portraits taken after arrest, originally for law enforcement to identify individuals.
• The Rogues Gallery is a police collection of suspect photos for identification, or shady characters, such as a "Mugshot" line-up.

Key Figures in Photography

• Alhazen (Ibn Al-Haytham) was an optics authority in the middle ages and invented the first pinhole camera (camera obscura), and explained image inversion.
• Sir John Frederic W. Herschel coined the term "photography" in an 1839 letter to Henry Fox Talbot.
• Joseph Nicephore Niepce was a French inventor and produced the first permanent image in 1826, using camera obscura.
• Niepce's photographs required 8 hours of light exposure, and would fade soon after appearing.

Developments in Photography

• Heliography (Sun Prints), invented by Joseph Niepce, employed sun and drawing in the first permanent light-recorded image.
• Louis Daguerre developed an improved photographic method called Daguerreotype, which reduced exposure time to under 30 mins, and stabilized images.
• The Daguerreotype was the first commercially successful photographic process that would not change if exposed to light.
• Henry Fox Talbot invented the first negative, from which positive prints were made.
• Talbot created the calotype process in 1841, a negative-positive process using paper.

Photography in Police Work

• Alphonse Bertillon pioneered photography as identification with anthropometry.
• Photography is used to identify: Prisoners, persons being investigated, unidentified remains, missing persons, civilian clearances, and lost items.
• Photography is a universal way to communicate due to not relying on language.

Photography for Recording and Preservation

• Photography records the original appearance and related areas for later use in investigations, court trials and hearings.
• Photographs preserve crime scenes and physical evidence, capturing the initial condition that can't be retained otherwise.

Discovering and Proving with Photography

• Photography extends vision to discover and prove things via magnification.
• Photomicrography magnifies small objects using a camera with a microscope,
• Photomacrography magnifies via extended tube lens.
• Microphotography reduces film scenarios to small strips.
• Macrophotography enlarges photos of small objects.

Specialized Photographic Techniques

• Telephotography captures distant objects with long focus lenses, and artificial light such as X-rays.
• Photography is used to present evidence in court meeting relevancy for admissibility.
• Evidence presented in court is called "EXHIBIT".
• Relevancy involves evidence origins and case relation, with supplemental photographs.
• Video cameras prevent crimes, making detection easier.

Photography in Police Training

• Photography is used for training purposes.
• Photography reproduces evidence, so experts can examine real specimens.

Different Photography Views at Crime Scene

• General views capture the overall crime scene to show direction and location.
• Medium-range views photograph the crime scene to show nature of the crime.
• Close-up views show evidence details.
• Extreme close-up views, commonly used in laboratories with magnification, capture bruises and traces.

Principles of Lighting

• Lighting is key to successful images, impacting darkness, tone, mood, and atmosphere through correct direction and angle.
• Light from illumination can be classified into three types: directional, side and backlight.
• Directional lighting uniformly radiates from the front, yielding small shadows.
• Side light creates clear shadows on the subject.
• Backlighting shines from behind, creating silhouettes and challenging exposure.

Light as Energy

• Light is electromagnetic energy emitting from heat.
• Light that is visible travels at 186,000 miles/second (air) or 300,000 km/sec (open space).
• The most important element in photography is light and includes visible or invisible light.
• Visible light triggers a sensation on human eyes/excites the retina.
• Invisible light wavelengths are either too short/long to excite a retina: X-Ray.

Quantum Theory and Light

• Max Planck discovered the Quantum Theory in 1900 and stated light waves travel as energy packets, called quanta or photons.
• It is the most accurate theory about light.
• Albert Einstein discovered light is wave-like photons that emit electrons, via the photoelectric effect.

Wavelength, Frequency, and RAT Law

• Wavelength measures distance between wave crests.
• Frequency measures waves passing a point per second.
• RAT Law means when light strikes something it is reflected, transmitted, or absorbed.

Types of Natural Light

• Natural light forms without human intervention and includes sun, stars, moon, bioluminescent organisms and natural phenomena.
• The sun is the major light source on Earth.
• Stars produce minimal light due to distance.
• The Moon uses sunlight and does not produce its own light.
• Bioluminescence comes from living organisms such as jellyfish.
• Natural phenomena includes Lightning or Volcanic eruptions

Qualities of Natural Light

• Intensity is the strength of light.
• Bright light has distinct shadows that requires faster shutter speed.
• Hazy light creates soft shadows that requires a slower shutter speed.
• Cloudy bright light has no shadows and diffuses the light.
• Heavy overcast conditions create low-contrast conditions and requires a compensation of 8 times the basic exposure for light decreases.
• Direction can be obvious from single sources, or absent with multiple or diffused sources.
• Light varies in color, depending on its source.
• Sunlight color varies, depending on atmospheric conditions.

Characteristics of Artificial Light

• Artificial lights are also known as man-made lights and used for indoor photography.
• Incandescent sources are objects heated to high temperature: Incandescent Lamp.
• Luminescent sources include fluorescent tube and electric bulbs.
• Gas Discharge Sources includes neon and sodium lamps.
• Flame is created from burning fuel and produces light, e.g., lanterns.
• Explosions illuminates intense light from war.
• Phosphorescence stores electricity and gradually emits light, such as glow-in-the-dark watch dials.

Properties of Light

• Light is electromagnetic radiation with wave properties.
• Visible light ranges from 380-730 nanometers (electromagnetic spectrum).
• Transparent material allows lights to pass, and opaque material absorbs it.
• Translucent material allows light to pass through, but distorts it.

The RAT Law

• Reflected Intensity + Absorbed Intensity + Transmitted Intensity = Incident Intensity.
• Kirchoff's Law states the intensity of involved light equals energy conversion.
• Gustav Robert Kirshoff discovered it in the 19th century.

Reflection and Absorption of Light

• Reflection is the bouncing back of light from a surface.
• Irregular or Diffuse Reflection means rays go in different directions, and occurs on rough surfaces.
• Regular/Specular Reflection means rays go in one direction, and occurs on flat or shiny surfaces.
• Absorption is when light converts to heat energy.

Light Interactions and Object Properties

• When light enters a transparent material, it dissipates to heat.
• If an object does not transmit/reflect light, it appears opaque.
• Dark Objects absorb more light and also hotter, compared to white.
• White light is a spectrum of all colors, and black is the absence of color and light.

Light Behavior and Terms

• A prism splits light into rainbow colors.
• Transmission is when Light passes through a substance, such as visible light in glass.
• Transparent transmits visible light, but translucent objects are not clearly seen due to being scattered or diffused.
• Refraction of light occurs when when waves change direction/ speed entering new object.
• Index Refraction measures light refracting in a medium.

Diffraction and Dispersion of Light

• Diffraction spreads light after passing through narrow opening and edge.
• Dispersion is when light splits into colors after differences in refraction.
• Dispersion is splitting white light when passing through a prism.

Scattering and Electromagnetic Properties

• Scattering of light is when passing from one medium to another and light is absorbed.
• Electromagnetic Radiation is energy radiating from a source.
• Electromagnetic Spectrum is wavelengths and energies of electromagnetic radiation.
• James Clerk Maxwell discovered the Electromagnetic Spectrum.

Electromagnetic Spectrum Types

• The Electromagnetic Spectrum types include: Radio/TV, Microwaves, Infrared, Light, Ultraviolet, X-Rays and Gamma Rays.

Key Camera Components

• A camera is a light-tight box using to form images, using a shutter and diaphragm.
• Cameras use a lens to create an image and regulate incoming light.
• Early cameras included pinhole and box cameras.

Pinhole and Camera Obscura

• A pinhole camera is a simple imaging device within a box or chamber.
• Camera Obscura means Darkened Room in Latin, and is a device projecting outside images upside down.

Box and View Cameras

• A box camera is a sealed fixed-focus camera with angled viewfinder mirrors.
• A view camera is a large format camera, with inverted images formed on glass screen at film plane.

Polaroid and Reflex Cameras

• A Polaroid Camera is an instant camera
• A Reflex Camera sees images through the lens.
• Reflex cameras allow optical view of scene using a mirror system.

Single Lens Reflex Camera (SLR)

• A Single-Lens Reflex (SLR) camera uses one lens for viewing and photographing with film.
• Forty-five degree mirrors form 45-degree images on cameras.

Digital Single Lens Reflex Camera (DSLR)

• A Digital Single-Lens Reflex (DSLR) combines single optic and digital sensors.
• DSLR cameras offer image quality, controls, and options similar to fixed lens cameras.
• DSLR uses memory cards or connectors.

Prism Effects in a DSLR

• Inside a DLSR body is light reflecting mirrors to viewers.
• In DSLRs, Prisms bend and color the light.
• Internal prisms transmit images on the focusing screen.

Main Camera Shutter Types

• Twin Lens Reflex Camera uses two lenses where one helps the viewer and the other takes photos with film.
• A camera lens refracts light to form images and can produce own image with tiny prisms.
• Aperture controls the amount of light hitting the image sensor, measured in F-stops, where each stop doubles the light.
• Camera Image Sensors are where captured light is turned into an image.
• Shutters control focal plane exposure duration, controlling the incoming light to the lens.
• Focusing Controls are an integral aspect of its operation.

Types of Focus and Shutters

• The focus is adjusted or has a varying focal plane.
• Types of focus incude a Scale Bed type (Focusing Scale), Micro Prism (Range Finder Type), B.1. Split Image, B.2. Con-Incidence Image and Ground Glass Type.
• A Diaphragm Leaf Shutter is a lens component for a clear hole that opens/closes at time, invented in 1912.
• A Focal Plane Shutter allows fast shutter speed and is less timing accurate.
• Large blades results accurate aperture

Shutter Types and Flash

• Camera Shutter types includes turning the sensor or capturing exposure.
• A Mechanical shutter uses pivoting metal leaves to prevent sensor and expose to light.
• Strobe Cubes, Slave units, Right lights and Accessory Flash are types of electric flash.

Accessory Flash Units and Flash Synchronization Speed

• Manual flash, Automatic flash, Dedicated lights, Built-in Flash, and Off-Camera Flash are accessory flash units.
• Flash Synchronization Speed is used with a flash for evenly lit results.

Camera Lens

• Lenses refract light to make an image.
• Lenses also are glass and have 2 special surfaces forming images.
• Lenses include magnifying glasses and compound, like microscopes.
• A convex lens is thick in the center or thin, bends outwards or focuses light.
• A concave lens is thin in center or spreading light, diverging etc.

Filter Thread Parts of a Lens

• Filter threads includes filter rings.
• Filter Thread is a section allowing accessories and lens shade.
• A section rotating has the picture or auto-focus lens.
• Manual Focus lens is with it in front, with a signal to force position/sharp.

Lens Markings and Indicators

• Distance Indicator is used for close ups.
• Lens Marking Specs numbers with lens is local / aperture / marking are mm.
• Depth of field moves the focus for F number.
• F number is measured numerically.

Additional Rings of a Camera

• Aperture ring adjusts the size of the hole
• A zoom ring enables changing it locally when shooting or at intervals too..
• Focal Length has a range of an image given.

Aperture of a Camera

• Aperture has light/element sizes capture elements.
• F numbers / double etc to expose more light on the image
• There are 2 images that are in or out of focus, and are determined by: lens.

Images and Gyroscopes

• Image Gyroscopes read the movement to help reduce motion blur.
• Photos can be adjusted with stabilization / sensor..
• One way to adjust a scene can through close positioning
• A Prime Lens also known as a Fixed Focal Lens , can change based off distance.

Wide Angle, Telephoto and Macro Lenses

• Narrow areas also magnify when near you, and are used to not get to close.
• All lenses is a 70mm-135 mm / 300 mm lenses that are high quality, used near a camera
• Special lenses ( used when making the toys)

Lenses that Distort Image

• Fisheye or shifts, and are used with special cameras
• Aberrations can occur in lenses, caused from imperfections in how it focuses/ reflects
• Images are also bent from distortion of the lens itself.

Chromatic Aberration

• Chromatic Aberration can be called the color finging of photos
• Lens not focus wavelength.

Longitudinal and Lateral Aberration

• Aberrations, caused from bokeh- fringing / blurry images/ transverse, change size image/ wavelength
• Chromatic aberration the is imperfection , can not focus on line or light
• Spherical images can focus on axis or clarity .

Film Emulsion

• Emulsion means project lines are curvy not flat.
• Project lens or area . and the axis which distortion

Silver Halide

• Film with silver halide is emulsion and reactions with dye additions with ultraviolet / blue light

Types of Film

• Photographic film records to store / with plastic over lead made emulsion
• A film is negative emulsion printing and with direct sun with glass.

More on Film

• The films are with dye transfer. or projector .same transfer that make black / reversal film ( small film or black and white -