Forensic Photography: A Review Center PDF

**POWERMIND REVIEW CENTER** **FORENSIC 1- FORENSIC PHOTOGRAPHY** THE DEVELOPMENT OF PHOTOGRAPHY - Camera Obscura- (Latin as Dark Room) it was known as the first pinhole camera that was able to develop a Photograph during the 13^th^-14^th^ century. It was invented by Alhazen (Ibn Al-Hayt...

**POWERMIND REVIEW CENTER** **FORENSIC 1- FORENSIC PHOTOGRAPHY** THE DEVELOPMENT OF PHOTOGRAPHY - Camera Obscura- (Latin as Dark Room) it was known as the first pinhole camera that was able to develop a Photograph during the 13^th^-14^th^ century. It was invented by Alhazen (Ibn Al-Haytam). - Joseph Nicéphore Niépce- a French inventor who produced the first permanent photographic image in 1825 which depicts a photo of the glass of the "Le Gras". - Louis Daguerre- he was a French artist who partnered with Joseph Nicephore Niepce to develop and capture a photo that will make it permanent and long-lasting by exposing it to mercury vapor. It was later on called as "Daguerreotype" - Henry Fox Talbot- The inventor of the first negative from which multiple positive prints. He perfected this paper-negative process and called it a "Calotype" (Greek for beautiful picture)which is being produced in a short time. He is also the inventor of the "Mouse Trap Camera" **Legal foundation of Photographic Evidence:** - **For black and white photographs:** 1859-Daguerreotype was use in civil case, Lueo vs. US (regarding the authenticity of photographs in comparing signatures) 1874-In criminal case introducing photograph as identification evidence, Underzook vs. Commonwealth - **For color photographs** 1943-Civil litigations Green vs. City and county of Denver Colorado, involving spoiled meat in violation of a health ordinance prohibiting the sale of putrid meat to the public. 1960- In criminal case, State vs. Conte, showing the graphic wound of the victim ### DEFINITION OF TERMS: {#definition-of-terms.ListParagraph} 1. ***Sir John F. W. Herschel*** coined the word photography when he first wrote a letter to Henry Fox Talbot. = Is the art and science of reproducing image by means of light through some sensitized material with the aid of a camera, Lens and its accessories and the chemical process required in order to produce a photograph. 2. 3. USES OF PHOTOGRAPHY =================== 1. **Personal Identification** 2. **For Communication** 3. **For Record Purposes** Different Views in Photographing -------------------------------- a. b. c. d. 4. **For Preservation** 5. **For Discovering and Proving** a. **The use of Magnification** **Telephotography** = Is the process of taking photograph of a far object with the aid of a long focus and Telephoto lens. 6. **For Court Exhibits** 7. **Crime Prevention** 8. **Police Training** 9. **Reproducing and Copying** ESSENTIALS OF PHOTOGRAPHY ========================= 1. **Light** = is an electromagnetic energy that travels in a form of a wave with the speed of 186, 000 miles per second. 2. **Camera** = a light tight box designed to block unwanted or unnecessary light from reaching the sensitized material. 3. **Lens** = is the light gathering mechanism of the camera that collect the reflected light coming from the object to form the image. 4. **Sensitized material** = composed of a highly sensitized chemical compound which is capable of being transformed into an image through the action of light and with some chemical processes. ( Film and Photo Paper). 5. **Chemical Process** = is the process necessary for reducing silver halides into a form so as a latent image and a positive image be made resulting to what we called Photograph. E. LIGHT: ITS NATURE, CHARACTERISTICS, SOURCES AND CLASSIFICATION Light is defined as an electromagnetic energy with the speed of 186,00 miles per second. Its wave travel is said to be characterized in certain extent based on velocity, wavelength and frequency of the number of vibration of the wave per second. Light wavelength is the distance measured between two (2) successive crest or through of wave and it is expressed in either Millimicron (nanometer) or Angstrom. **Millimicron** is the units of light wavelength which is equivalent to one-millionth part of a millimeter which the **Angstrom** is relatively smaller for it has an equivalent measurement of ten (10) millionth part of a millimeter. Once light hits a certain medium, its action can be characterized as either: **Reflected, Transmitted or Absorbed** (RAT). **Reflected** once the light hits a mirror and it bounce back. **Transmitted** when the light hits a transparent glass which would allow the light to pass through its medium and **Absorbed** when the light hits a dark colored object and prevents it from either bouncing or passing through. Isaac Newton in 1666 proved that the light which men see as white light is actually a mixture of all colors of the spectrum. This is produced when we allow light to hit a glass prism (Sharp Edge of the Glass). A rainbow array will then be shown with colors red, orange, yellow, green, blue and violet colors (from top to bottom). The visible light is also said of have a wavelength of between 400-700 millimicron or nanometer. - **Types of Light** a. **Visible Light** b. **Invisible Light** **2. Photographic Rays** a. **X-ray** b. **Ultra-violet ray (Before the violet)** c. **Visible Light** d. **Infra-red (Beyond the Red)** **3. Light Source** **A. Natural Light=** are those light which come to existence without the intervention of man e.i. Sunlight, moonlight and starlight. 1. **Bright Sunlight** 2. **Hazy Sunlight** 3. **Dull Sunlight** **B. Artificial Light =** **otherwise known as man-made light e.g. fluorescent bulb, incandescent bulb and photoflood lamp.** #### 4. SENSITIZED MATERIAL = It refers to the film and photographic paper that basically composed of emulsion containing Silver Halides suspended in gelatin and coated on a transparent or reflective support. **Parts of the Sensitized Material** 1. **Emulsion** = is that part of the film or photographic paper which contains the silver grains which is the one sensitive to light. In a colored film this emulsion surface can be composed of Three layers ( Blue, Green and Red) with filters intervening. 2. **Anti Halation Backing** = Is the one designed to hold back the light and prevents halation. 3. **Base** = Support the emulsion #### 5. CAMERA Is a light tight box with light gathering device and a means of blocking unwanted or unnecessary light from reaching the sensitized material. Basically, camera can produce image with its four-(4) basic parts such as light tight box, lens, and shutter, Holder of sensitized material. #### Essential Parts of a Camera 1. Light Tight Box -- a box designed to keep light out and serve as a frame to hold other parts. 2. Lens -- designed to collect or to focus the reflected light from an object to form an image on the film. 3. Shutter -- designed to control the time during which the light reaches the film 4. Holder of the sensitized material -- located at the opposite side of the lens designed to hold firmly the sensitized material to prevent the formation of the multiple or blurred image 5. View finder -- designed to determine the field of view of the camera or the extent of the coverage of the given lens OTHER PARTS OF A CAMERA ======================= ##### Viewing System A. **Film Advancer** (film advance lever or knob) =designed to transfer the exposed film to the other side or to the take up spool and the unexposed film will be the opposite side of the lens for another exposure. B. **Shutter speed** = is that part of the camera which regulates the time exposure of the film thus, affecting the amount of light reaching the sensitized material. It is usually expressed in a fraction of a second. The speed number in the left is always two times powerful in terms of light gathering than that of the right number Using a fast shutter speed the photographer can stop or "freeze" the action of a person provided that necessary adjustment on the lens opening be made in order to maintain normal exposure. C. **Lens Aperture** = the ratio between the diameter of the whole lens in relation to the focal length of the lens. It is the light gathering power of the lens. Otherwise known as lens opening or relative aperture and it is expressed in F-number. **f 2.8 f-4 f-5.6 f-8 f-11 f-16** The lower the f-number, the bigger the lens opening and the bigger the lens opening the greater the volume of air that will passed through the lends and reach the sensitized material. If the objective of a photographer is obtain the widest possible coverage of the lens in which objects are all sharp, It will be advisable to used a smaller lens opening. D. **Focusing** = is that mechanism of a camera designed to control the degree of sharpness of the object to be photograph. It is usually obtained by estimating the distance from the camera and that of the object that will make a sharp or clear image. TYPES OF THE CAMERA =================== 1. **View Finder Type** -- it is considered as the smallest and the simplest type of camera 2. **Single Lens Reflex Camera** -- it is a type of camera best suited for police work due to its interchangeability of the lens 3. **Twin Lens Reflex Camera** -- A type of camera with dual lens, one for focusing and the other for forming the image. 4. **View or Press type** -- is considered the biggest and expensive type of camera, used for movie making 5. LENS ==== = It is the image-forming device of the lens that actually has a greater effect on the quality of the image to be formed. **Daniel Barbaro** = first to introduce the use of lens in the camera. CLASSIFICATION OF LENSES ======================== 1. **According to the type of image to be produced** a. Positive or Convex Lens (Converging Lens) Characterized by the fact that it is thicker at the center and thinner at the side which is capable of bending the light together and forms the image inversely. b. Negative or Concave Lens (diverging Lens) Characterized by the fact that it is thinner at the center and thicker at the side and forms the virtual image on the same side of the lens. LENS CHARACTERISTICS ==================== 1. **Focal Length --** is the distance measured from the optical center of the lens is set to focus at infinite position. As according to focal lenses may be classified as: a. Wide Angle or Short Focus = with focal length not longer than the diagonal half of the negative. Useful in taking photograph at short distance with wider area coverage. b. Normal or Medium Focus = with focal length approximately equal but not longer than twice the diagonal half of the negative. c. Long or Telephoto Lens = with focal length longer than twice the diagonal half of the negative. Best used in long distance photographing but with narrow area coverage. 2. **Relative Aperture --** the light gathering power of the lens expressed in F-number d. Depth of Field -- is the distance measured from the nearest to the farthest object in apparent sharp focus when the lens e. Hyperfocal distance = Is the nearest distance at which when a lens is focused with a given particular diaphragm opening will gives the maximum depth of field. 3. **Focusing =** is the setting of the proper distance in order to form a sharp image. The one that controls the degree of sharpness of the object.