Photography: Intro, History, Basic Camera Function Flashcards
How do photographs assist in a forensic investigation, specifically in relation to the crime scene?
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Accurately depicts scene as it appeared upon arrival
Provides visual for investigators, witnesses, victims, and judiciary to understand the scene
Metaphorically puts people into the scene
What could alter a crime scene between the crime and the arrival of forensic investigators?
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- Weather
- Clean up
- Victim
- Animals/insects
- First responders
- Time (degredation, sun, UV, decomp)
Aside from the benefits for scene investigation, how else can photography aid forensic investigators?
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- Locating tool (suspects, missing persons, property)
- ID suspects
- Disaster victim ID
- Charting for court
- Safe and acceptble alternative to display contaminated, hazardous or dangerous evidence
- Disclosure requirements
Outline the three main types of photographs that need to be taken to document a crime scene.
- Overall scene description (4 corners)
- Midrange of particular points of interest
- Close up of minutiae, fine detail
What is photography?
The art or process of producing images by the action of radiant energy and especially light on a sensitive surface (e.g., film, optical sensor)
When was the camera obscura created?
17th century
What was an alternative name for the camera obscura?
Dark Chamber
Describe how the camera obscura worked
- Consists of box or room with hole in one side
- light from external scene passes through hole and strikes surface inside
- Image is rotated 180 degrees, perspective and colour preserved
- Can be projected onto paper then traced
What did Isaac Newton discover in 1666?
Divides sunlight with a prism and discovers that white light is composed of seven distinct colours
What did Prof. J. Schulze contribute to photography?
Mixed chalk, nitric acid and silver in a flask and noticed darkening on side of flask upon exposure to light.
Who is credited with creating the first photo-sensitive compound? When?
Prof. J. Schulz in 1727
What was the first practicable photographic process?
Daguerreotype
Outline the Dagguerreotype process.
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Using camera obscura, a light tight plate holder was designed to hold a copper plate faced with a thin layer of silver.
Prior to exposing the plate in the camera, it was made light sensitive by iodine crystal fumes.
After exposure, mercury fumes would develop the image.
Image was then fixed in a sodium chloride solution
The plate could be toned in gold chloride
When was the Dagguerreotype developed?
19th century
Who developed the Dagguereotype?
Nicephore Niepce and Louis-Jacques-Mande Daguerre
What was the Calotype and what was its significance?
A more sensitive photographic process that reduced exposure time
Outline the process of the Calotype.
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- Paper soaked in silver nitrate and potassium iodide, rinsed in solution of gallic acid and silver nitrate
- Exposure
- Latent image developed in gallic acid solution
- Positive print created by contact printing onto another sheet of light sensitive paper
Who was the first person to use the phrase “photography” and when did this occur?
Sir John Herschel in 1839
Who founded the Eastman Kodak Company?
George Eastman
What was the significance of the founding of the Eastman Kodak Company?
Popularized the use of roll film, helping to bring photography to the mainstream.
When did Eastman found the Eastman Dry Plate Company?
1880
Who founded the Polaroid camera?
Edwin Land