Forensic Photography Lecture 1 Introduction
Forensic Photography
Forensic: to be used in litigation activities
Photo: the use of light
Graph: to write, sketch, or graph
“To write with light for legal purposes”.
Three forms of Documentation
Notes
Sketches
Photography
All three rely heavily on visual stimulation for input Sketching was first:
The caveman and the wall drawings
The Egyptians and Hieroglyphics, a written language using drawings
Notes are the use of symbols that code for thoughts
Photography records an image produced with light just as our eye records an image in our mind
Two scientific processes needed for photography to happen
Creation of Optics
Light Sensitive response
Chemicals (Silver Halides)
Silicon Chips (CCD or CMOS)
Camera contains these items
Camera Obscura
Early Pin-hole camera with no film for permanently recording an image
Pin-Hole Camera
Some cameras have no glass optics
Pin-Hole
Camera Picture
Focal Length: 125mm
Pinhole: 0.5mm
Exposure Time: 3 seconds
Super Wide Angle
Equivalent to a 18mm lens on a 35mm camera.
Wide Angle
Equivalent to a 27mm lens on a 35mm camera.
Normal or 1:1
Equivalent to a 55mm lens on a 35mm camera.
Telephoto
Equivalent to a 82mm lens on a 35mm camera.
The Light Sensitive Media
Light interacts and creates chemical change
The changes are not all sufficiently:
Sensitive
Permanent
Early successful media used wet silver halides process:
Daguerreotype: a positive on copper coated with a thin layer of silver
Calotype: a paper negative that could be used to create a positive. Useful for making copies
Silver halides continue to be the chemicals used to create the latent image in modern films
The Light Sensitive Media
Many improvements were made
Collodion process: a wet process that reduced exposure times to two or three seconds and was cheaper
Wet process required a considerable amount of equipment on location
Dr. Richard Maddox used Gelatin as a basis for the photographic plate. This led to the development of the dry plate
The
Forensic: to be used in litigation activities
Photo: the use of light
Graph: to write, sketch, or graph
“To write with light for legal purposes”.
Three forms of Documentation
Notes
Sketches
Photography
All three rely heavily on visual stimulation for input Sketching was first:
The caveman and the wall drawings
The Egyptians and Hieroglyphics, a written language using drawings
Notes are the use of symbols that code for thoughts
Photography records an image produced with light just as our eye records an image in our mind
Two scientific processes needed for photography to happen
Creation of Optics
Light Sensitive response
Chemicals (Silver Halides)
Silicon Chips (CCD or CMOS)
Camera contains these items
Camera Obscura
Early Pin-hole camera with no film for permanently recording an image
Pin-Hole Camera
Some cameras have no glass optics
Pin-Hole
Camera Picture
Focal Length: 125mm
Pinhole: 0.5mm
Exposure Time: 3 seconds
Super Wide Angle
Equivalent to a 18mm lens on a 35mm camera.
Wide Angle
Equivalent to a 27mm lens on a 35mm camera.
Normal or 1:1
Equivalent to a 55mm lens on a 35mm camera.
Telephoto
Equivalent to a 82mm lens on a 35mm camera.
The Light Sensitive Media
Light interacts and creates chemical change
The changes are not all sufficiently:
Sensitive
Permanent
Early successful media used wet silver halides process:
Daguerreotype: a positive on copper coated with a thin layer of silver
Calotype: a paper negative that could be used to create a positive. Useful for making copies
Silver halides continue to be the chemicals used to create the latent image in modern films
The Light Sensitive Media
Many improvements were made
Collodion process: a wet process that reduced exposure times to two or three seconds and was cheaper
Wet process required a considerable amount of equipment on location
Dr. Richard Maddox used Gelatin as a basis for the photographic plate. This led to the development of the dry plate
The