Forensic Photography PDF

# Principles of Photography ## Module 1: Lesson 2 - A photograph is the mechanical and chemical result of photography - To produce a photograph, light is needed aside from sensitized materials - Lights reflected or radiated by a subject must reach the sensitized materials while all other lights mu...

# Principles of Photography ## Module 1: Lesson 2 - A photograph is the mechanical and chemical result of photography - To produce a photograph, light is needed aside from sensitized materials - Lights reflected or radiated by a subject must reach the sensitized materials while all other lights must be excluded - The exclusion of all unwanted and unnecessary lights is achieved by placing the sensitized material inside a camera - The amount of light on the sensitized material after exposure is not immediately visible to the eyes - To make the formed image visible, it must undergo the development process - The visual effect that results from the chemical processing is dependent on the quantity and quality of the exposing light - More light will yield an opaque or black shade on the sensitized material after development - Too little light will produce a transparent or white shade - The varying shade of gray will finally form the complete image - The effect of light on the sensitized material is not visible in the formation of images of objects. The effects could made visible with the aid of chemical processing of the exposed sensitized material called development ## Police Photography - The science which deals with the study of the principles of photography and the preparation of photographic evidence and its application to police work. ## Four Primary Ways of using Photography in Police Work - As a means of identification - As a method of discovering, recording, and preserving evidence - As a way to present, in the courtroom, an impression of the pertinent elements of a crime - As a training and public relations medium for police programs ## Objectives of Police Photography - Produce a pictorial record of everything on the crime scene - It keeps police officer's memory accurately as to where he find things - It helps in securing confessions, disposition and information relating to the case ## Importance of Forensic Photography - It presents minute details of the crime scene - It is a permanent record of the crime scene - It aids the investigator to describe in court details of the crime scene that he investigated several months ago - It assists the investigator to solve crime ## Forensic Photography - Is a science which deals with the study of notion of photography, its application to law enforcement work and the preparation of photographs for court presentation. - The process of photographing crime scene or any other objects for court presentation ## Macro Photography - Is the art or process of photographs an object at greater than 1:1 ratio up to nine times magnification. - Photographing of objects directly enlarged on the negative and magnified from 1 to 9 times ## Micro Photography - Is the art or process of photographing minute objects and magnified by means of the microscope and enlarge from 10 times up ## Ultra Violet Photography - Is the art or process of photographing unseen objects by the naked eye with the use of ultra violet rays and filters. ## Infrared Photography - Is the art or process of photographing or recording unseen objects by the naked eye by means of infrared light ## X-Ray Photography - The process of photographing or recording internal structure of the body. ## Aerial Photography - A kind of photography applied for photo mapping ## Underwater Photography - Photographing things under water. ## Flash Photography - Applied to the technique whereby exposures are made with illumination from one or more photograph. ## Mug Shot Photography - The process of taking photographs of the suspect/s in full length, half body, right and left side views, and two quarter views. - It is usually use for personal identification which is the first use of photography in police work. ## Evidence Photography - Many valuable articles of evidence can be found at the crime scene. Each object can be photographed individually and in relation to other objects at the scene. Examples of evidence to be photographed are: Tools, Weapons, Clothing, Contraband ## Purpose of Photographing Physical Evidence - A permanent record is made of the original appearance of the object. - The photographs can be used in place of physical evidence to supplement the case report. - Each article is preserved from necessary handling which might cause the evidence to deteriorate or otherwise become altered. - A photograph should be taken at the scene of any piece of evidence that might deteriorate, change over time, or any evidence that cannot be moved from the scene or that might be damaged by handling ## Basic Requirement of a Photograph Admitted as Evidence in Court - Accurate Representations - Free of Distortion - Material and Relevant - Unbiased ## A.M. No. 01-7-01-SC Rules on Electronic Evidence - "Ephemeral electronic communication" refers to telephone conversations, text messages, chatroom sessions, streaming audio, streaming video, and other electronic forms of communication the evidence of which is not recorded or retained. ## A.M. No. 01-7-01-SC Rules on Electronic Evidence Rule 11: Audio, Photographic, Video, and Ephemeral Evidence - Section 1. Audio, video and similar evidence. - Audio, photographic and video evidence of events, acts or transactions shall be admissible provided it shall be shown, presented or displayed to the court and shall be identified, explained or authenticated by the person who made the recording or by some other person competent to testify on the accuracy thereof. # Elements of Photography ## Module 2: - Images or subject - Sensitized material - Light - Camera - Chemical ## Light - Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which visible to the human eye and is responsible for the sense of sight. ## Optics - The science behind how the human eye works - The study of light and the interaction of light and matter. The observation and study of optical phenomena such rainbows and the aurora borealis offer many clues as to the nature of light. ## Electromagnetic Spectrum - Colors of the sunlight that is separated is called the spectrum - One way to see the spectrum of sunlight is by using a prism made of glass or plastic. Another way is to look at a rainbow. - The light is bent and because some wavelengths bend more than others, the colors are separated. - Violet rays are bent the most. - Red rays are bent the least. - The whole range of radiant energy includes radio waves, microwaves, infrared light, visible light, ultra violet light, x-rays and gamma rays. - Visible light, which makes up only of a tiny fraction of the electromagnetic spectrum, is the only electromagnetic radiation that humans can perceive with their eyes. ## Visible Spectrum - Is small part of the electromagnetic spectrum where the visible light is found, the portion of the electromagnetic spectrum that affect the human sense of sight. Visible light includes all those radiation having a wavelength ranging from 400-700 mu. - When sunlight shines through a prism, you can see all the colors of the rainbow (or visible spectrum). In fact, daylight is a mix of all colors. All the colors of nature come from light. | Primary Colors | Approximate Wavelength | Complementary Colors | Approximate Wavelength | |--------------------------------------|------------------------|---------------------------------|------------------------| | Red (longest wavelength) | 700 mu | Magenta (shortest wavelength) | 400 mu | | Blue | 450 mu | Cyan | 500 mu | | Green | 550 mu | Yellow | 590 mu | ## Neutral Colors - Gray - White - Black ## Primary Colors - The three primary colors are Red, Green, and Blue. - White light can be made by mixing red, blue, and green. - The process of making colors by mixing primary colors is called addition, because one color is added to another. ## Secondary Colors - Colors made by combining two primary colors. The are yellow (red and green), cyan (blue and green), and magenta (blue and red). When the primary colors are mixed in different proportions, any color at all can be produced. ## Color Mixing **Additive Color Mixture** - R+B+G=W - R+B= M - R+G=Y - B+G=C - M+Y=R - M+C=B - Y+C=B **Subtractive Color Mixture** - W-R=C - W-B= Y - W-G=M - W-C=R - W-Y=B - W-M=G - C-G=B - Y-G=R - I-R-G ## Color Temperature - The color temperature of a light source is a numerical measurement of its color appearance. It is based on the principle that any object will emit light if it is heated to a high enough temperature and that, as the temperature increase, the color of that light will change along with the temperature. - If you have ever seen a blacksmith at work heating a horseshoe, you would see that the horseshoe glows "red hot." It was heated enough so that it gave off light, red light in this case. Keep heating it an dit would go from red to orange to yellow to white and, finally, to blue white - A light source's color temperature, then, is the temperature at which the color of the horseshoe would match the color of the light source. We express this temperature in degrees in Kelvin. ## Sources of Light - **Natural Light:** The source of all daylight is the sun. The combination of color and contrast ascertains the quality of the daylight. Ex: Sun, stars, lightning, fire, Aurora Borealis ## Natural Light - Color of the daylight will also affect the appearance of the objects being photographed specially in color photography - Factors affecting the color of the daylight: - Atmospheric vapor - Atmospheric dust - Reflected light reached the objects and directly coming from the source ## Classification of Daylight According to Intensity - The appearance of the shades of the objects must be considered to distinguish this classification. **1. Bright Sunlight:** the subject will produce strong shadows because the source of light is not covered and the objects or subjects appear glossy in open space due to direct sunlight and reflected light coming from the sky which act as a reflector. **2. Hazy Sunlight:** the sun is covered by thin clouds and the shadow appears bluish because of the decrease of light falling on the subject in open space. The shadow cast is transparent to the eye and more details are visible under this lighting condition than a bright sunlight. **3. Dull Sunlight:** the sun is totally covered by thick clouds. No shadow is cast to the uniform illumination of lights all around the subjects in open space. ## Source of Light - **Artificial Light:** Almost all artificial light sources can be used in photographing of objects, as long as the light is capable of exposing the sensitized materials. Some of the artificial lights are electronic flash, photoflood lamp, fluorescent lamp, infrared lamp, and ultraviolet lamp. ## Mediums of Light - These are mediums that merely slow down the speed of light but allow to pass freely in other respects, transmit 90% or more of the incident light. ## Translucent Objects - These are mediums that allow light to pass through it in such a way that the outline of the source of light is not clearly visible, transmit 50% or less of the incident light. ## Opaque Objects - A medium that can divert or absorb light, but does not allow lights to pass through, they absorb most of the light while reflecting some of it. ## Mediums of Lights - A diagram of opaque, translucent and transparent objects ## Ways Light Can Interact with Matter - Light waves travel in straight lines. When light waves encounter an object or new medium, they act in one or more of the following ways: - They may be reflected - They may be absorbed - They may be transmitted - Light can pass through matter. (Transmission.) - Light can bounce off matter. (Reflection) - Light can be absorbed by matter. (Absorption) ## Reflection of Light - Reflection refers to the rebounding or deflection of light. The angle of reflection depends upon the angle of the light striking the material, which is referred to as the angle of incidence. - When light is reflected, it acts in a certain way. When the reflecting surface is smooth and polished, the reflection is orderly or specular. Specular light is reflected at the same angle of the surface as the light incident to the surface; that is the path of the light reflected from the surface forms an angle exactly equal to the one formed by its path in reaching the surface. - Thus the angle of reflection is equal to the angle of incidence, which is a characteristic of specular light. - If the object or surface is not smooth and polished, but irregular, light is reflected irregularly or diffused; that is, the light is reflected in more than one direction. ## Absorption of Light - When light strikes a medium and is neither reflected nor transmitted, it is said to be absorbed. When light comes in contact with the surface of an object, a certain degree of reflection, and some absorption, always takes place. - A medium that does not allow light to pass through is called opaque. ## Transmission of Light - Light rays may also be transmitted. They may also pass through some medium they encounter. When objects can be clearly seen through the medium, the medium is transparent. - A transparent medium transmits light rays in a regular, or uniform, pattern. When the medium transmits light but breaks up the orderliness of the pattern, sending the transmitted rays in many directions, the medium is translucent. ## Refraction of Light - Refraction is the bending of light rays when passing through a surface between one transparent material and another. - When the material in the path of the light is transparent a change in the direction of the light occurs. - The change of the direction that occurs when a ray of light passes from one transparent substance into another substance of different density. - Refraction occurs because light travels at different speeds in different transparent substances. ## Dispersion of Light - The speed of light in a medium depends on the wavelength of the light. As light enters a denser medium, the short waves are slowed more than the long waves.