Week 03_Crime Scene Photography
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Transcript Week 03_Crime Scene Photography
Forensic Photography:
An Overview to Recording the Scene
History
The camera has a long and distinguished
history as a means of recording phenomena
from the first use by Daguerre and FoxTalbot, such as astronomical events
(eclipses for example) and small creatures
when the camera was attached to the
eyepiece of microscopes (in
photomicroscopy).
History
The camera also proved useful in recording
crime scenes and the scenes of accidents,
one of the first applications being at the
scene of the Tay Rail Bridge disaster of
1879. The court, just a few days after the
accident, ordered James Valentine of
Dundee to record the scene using both long
distance shots and close-ups of the debris.
The set of accident photographs was used in
the subsequent court of inquiry.
History
They show that, in the words of the Public
Inquiry the bridge was badly designed,
badly built and badly maintained. (Below is a
picture of one of the bridge columns). The
methods used in analyzing old photographs
are known as forensic photography.
History
But when did actual crime scene photography begin?
Mary Jane Kelly was murdered by Jack the Ripper
on November 9, 1888 (5th and last victim) and
photographed in her room. (newspaper photo)
History
Emma and Andrew Borden were murdered on August
4, 1892 at Fall River, Massachusetts and
photographed as they were found.
History
Alphonse Bertillon started photographing crime
scenes around Paris circa 1890. 19th-century
revolution in forensic imaging
Forensic pathologists began using pictures and
words to show how various conditions appear in
the cadaver, and to teach students and colleagues
new methods of analysis. Line drawings, half-tone
photography, and chromolithography, which could
render coloration, texture, and subtle shading,
became increasingly common as improvements in
print technology made detailed illustrations
cheaper to produce.
Crime Scene Photography
Photographs taken at a crime scene:
1. Show the layout of the crime scene
2. Show the position of collected and
uncollected evidence
3. Show the point of view of victims,
suspects, and witnesses
4. Show the original condition of items of
evidence at the scene
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Film Photography
Photographic film consists of a sheet of
silver halide grains which “expose” when
exposed to light.
Film speed is a measure of the lightgathering capacity of the film.
Special types of film include Polaroid film
and Infrared film
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Digital Photography
A digital photograph is made when a light sensitive
microchip captures light on each of millions of tiny
picture elements, called pixels.
The light is recorded on each pixel as a specific electric
charge which is read by the camera as image
information which is stored as a file on a memory card.
The number of pixels is directly related to the resolution
of the picture. Photographs with more pixels show
increasingly good resolution, or more detail and
sharpness in photographs.
The number of pixels that a camera features is usually
measured in millions of pixels, or megapixels.
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Cameras
The most commonly used camera at crime
scenes is the Single Lens Reflex (SLR) camera
or the Digital Single Lens Reflex (DSLR) camera.
SLR and DSLR cameras allow for the use of
various accessories such as lenses, flashes, and
filters.
SLR and DSLR cameras also allow for manual
adjustment of camera settings, such as aperture
and shutter speed, that affect image quality.
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Lenses
The camera lens bends light to focus an image
on the film or digital microchip.
The lens’s focal length, the distance between the
lens and the image projected on the film or
microchip, determines the area shown in the
resulting photograph.
Normal Lens
--Focal length of 50-55mm and used for most
photographs that need to be taken at a crime scene
because it can show as much area as half a wall
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Lenses
Telephoto Lens
-- Focal length of 100 mm or greater and used to magnify
images.
Wide-angle Lens
--Focal length of 35 mm and used to show much more
area in one photograph than a normal lens
Macro Lens
--Focal length of less than 50 mm and used for highlydetailed close-up photographs
Multi-purpose Lens
--Focal length from 28-80 mm used to take normal, wideangle, and telephoto photographs
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Aperture and Shutter Speed
The camera aperture is a measure of the
diameter of the opening of the diaphragm,
which allows light to reach the film or microchip.
On film or digital cameras, one adjusts the
aperture by setting the f-number
--The lower the f-number setting, the wider the
aperture and the more light is allowed in.
The shutter speed is the length of time that
the film or microchip is exposed to light.
The shutter speed is measured as a fraction of a
second by factors of 1/2 (i.e. 1/2, 1/4, 1/8, etc).
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Depth of Field
The depth of field shown in a photograph
is the amount of area in the foreground and
background of an object in focus that is also
relatively in focus.
The smaller the aperture opening, the
greater the depth of field will be. This
means that higher f-number settings will
yield higher depth of field.
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DSLR Modes
The “auto mode” automatically selects an appropriate fstop and shutter speed for conditions being
photographed.
The “sports mode” captures subjects in motion by using
a higher (faster) shutter speed.
The “night mode,” uses a lower (slower) shutter speed
to gather as much light as possible to create the image.
The “landscape mode” automatically selects higher fstops to improve depth of field.
The “portrait mode” selects lower f-stops to decrease the
depth of field and make the subject stand out clearly
against a blurred background.
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Illumination
The color temperature of a light source is
“hot” if it has a bluer hue, while a “cold” light
source has a red-orange hue.
Light meters on film or digital cameras allow
photographers to measure the amount of light in
a shot.
A flash unit can produce either direct reflective
lighting or oblique lighting, which is achieved by
positioning the flash at an angle less than 90° to
the surface to show detail.
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Filters
Barrier filters block one specific
wavelength (color) of light from reaching the
film or microchip, making areas of that color
appear lighter in the photograph.
Bypass filters allow only a small range of
wavelengths of light to reach the film or
microchip and block all others.
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Tripods
Using a tripod to take photographs
eliminates the possibility of blurred photos
resulting from unsteady hands.
For crime scene photography, it is useful if
the tripod has
1) Independently adjustable legs suitable for
uneven terrain
2) A level to ensure 90º images of evidence
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Crime Scene Photography Log
A log of each photograph taken at the crime scene
is kept by the CS photographer.
The top of the photography log form includes
--case number, type of scene, date, location of scene,
description of the camera and lenses being used, film type
and speed (if applicable), and the photographer’s name and
title
For each photograph, the log records
--date and time the photograph was taken, the location of
the picture, the f-stop and shutter speed settings, the
lighting used and the lighting angle (if applicable), and a
brief description of the subject of the picture
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Crime Scene Photography
Crime scene photographs should record the area in
which the crime actually took place and all adjacent
areas where important acts occurred.
The most important prerequisite for photographing
a crime scene is for it to be in unaltered condition.
Each crime scene should be photographed as
completely as possible in a logical succession. The
sequence will show the overall scene first, then
work down to individual pieces of evidence that
jurors in the trial can easily relate back to the
larger scene
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Crime Scene Photography
Overview photographs of the entire scene and
surrounding area, including points of exit and
entry, are taken first.
--Taken from the outside borders of the scene and from
various angles
--Include a “visual tag,” an object recorded in multiple
overview photographs, to help visually piece the scene
together
Medium-range photographs show the layout
of smaller significant areas of the crime scene.
--Include at least one photograph of the “center” of the
scene
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Crime Scene Photography
Close-up photographs are taken last and show
greater detail of individual objects or evidence.
--Taken at a 90º angle to the object, with and without
evidence markers and scales
--For three-dimensional objects, oblique lighting may be
needed to show depth details
The four minimum photographs required at a
crime scene are an overview photograph, a
medium range photograph, a close-up
photograph, and a close-up photograph with a
scale.
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Special Crime Scene Photography
Night photography – requires the use of external
lighting or “painting with light.”
Indoor photography – requires photographs of
the neighborhood, points of entry and exit, and
all walls, floors, and ceilings.
Outdoor photography – requires location of
photographs to be recorded by a Global
Positioning Device or measurements from
landmarks.
--May include aerial photographs
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Special Crime Scene Photography
Arson photography – requires photographs of the point
of the fire’s origin and use of special equipment or
techniques to provide maximum contrast in photographs
of charred areas.
May also include photographs of crowd outside
scene because arsonists commonly return to scene
Sexual assault photography – requires photographs of all
wounds and clothing while showing discretion to the
victim.
Impression photography – requires oblique lighting to
show details and a scale to later create a 1:1 scale
photograph for comparison to footwear or tire samples.
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Special Crime Scene Photography
Bloodstain photography – requires photographs
of all pertinent stains and determined area of
convergence or area of origin.
--Bloodstains treated with luminol photographed in
complete darkness
Latent fingerprint photography – require
photographs with a 1:1 scale using a special
latent fingerprint camera or a regular camera
fitted with an adapter.
--Black and white film used to show greater contrast
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Digital CS Photography
Advantages of digital crime scene photography
include
1. The ability to observe images immediately after taking
them ensures important photographs are clear and show
the best possible detail.
2. The resolution available can exceed 6 megapixels,
while the maximum resolution offered by a film SLR
camera is equivalent to about 5 megapixels.
3. Computer programs can stitch digital crime scene
images together to create a 3-D view of the crime scene.
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Digital CS Photography
Digital
images are easily manipulated
using computer programs and may
not show an accurate depiction of the
crime scene.
Digital images may lose image data
or details through compression.
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Digital CS Photography
Law enforcement agencies ensure the
admissibility of digital CS photographs by
1. Developing Standard Operating Procedures that must
be followed
2. Saving images to writable (not rewritable) disks by
lossless compression
3. Saving enhanced or altered images as separate files
4. Keeping a detailed and accurate photography log
5. Submitting testimony from the crime scene
photographer as to the accuracy of the digital images
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Videotaping Crime Scenes
As with still crime scene photography, the crime
scene video must include overview, mediumrange, and close-up images.
A narrated crime scene video combines
photography and notes.
--However, it is important that only one person narrates
and no side conversations are captured on the video.
Some video cameras can produce still
photographs, but the quality is often poor.
--Therefore, still photographs from a film or digital
camera are still required.
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Camera Talk
Aperture = f-stop. It relates to the size of the
opening in the lens.
Moving the f-stop down one full stop doubles the
amount of light let into the camera. Moving up cuts
the amount of light by ½.
Shutter speed refers to the time the shutter is
open. A shutter speed of 1/1000 lets in less light
than a shutter speed of 1/500.
Film speed refers to the sensitivity of the film or
the digital sensor. ISO 100 is less sensitive than
ISO 400.
Perspective refers to the spatial relationships in the
image. Objects far away appear to be smaller and
to converge along lines.
Camera Talk
TTL refers to through the lens metering.
SLR refers to single lens reflex.
The preferred camera position is with your arms
and elbows in as much as possible.
Level tripods and the camera, and take most
photos from eye level.
Depth of field refers to the range of distances in
which objects are in focus. An f-stop of f/22 gives
greater depth of field than an f-stop of f/8.
Light Talk
Light is measure by wavelength and the unit of
measurement is usually the nanometer (m x 10-10).
The human eye can usually see from about 350
nanometers to about 650 nanometers, violet to
red.
Light for photography purposes can be
manipulated by shutter speed, aperture setting,
film speed, filters, exposure control, lens type,
flash and extra light.
Light Talk
Side lighting can help with shadows and
enhancement of detail.
Time exposure allows the opportunity for more
light.
Fill flash and painting are adding light techniques.
Camera Parts
Film wind lever.
Shutter plane and shutter speed setting ring or
device.
Flash attachment or hot shoe attachment.
Depth of field scale. Remember to focus, look at
the f-stop and then read the f-stop on each side of
the focus distance for the depth of field distance.
Focusing ring.
F-stop ring.
Flash synch speed.
View finder and TTL.
ISO setting ring or menu button.
Protocol
Check your equipment and make sure you have what you
need.
Take overall or overview, medium or mid-range, and closeup photographs.
Keep a log of your photographs or images.
Ensure that you have a legal right to take photographs. Do
you need a search warrant or a consent to search.
Maintain chain of custody of the recording medium and
developed images.
Does your photograph or image truly and accurately reflect
what you saw with your eyes.
Survey The Scene
One role of the crime
scene photographer is to
capture as much
information as possible
relating to the scene.
Consider the crowd and
on-lookers when taking
overall photos.
Some agencies like to
have a set of exit photos
to include exterior overall
photos.
Composition
Include references: landmarks, street signs,
scales, placards.
Fill the frame with the subject matter.
Set the camera for the maximum depth of field for
clear images.
Take photos with and without placards, and with
and without scales.
Fill flash, if appropriate to remove shadows.
Create shadows for enhancement of detail.
Tell a story sequentially and thematically.
Overall Photography
Wide angle lens with
35mm, and/or video with
zoom – outdoor/indoor.
Move around the points
of the compass.
Show overall layout of
scene, and spatial
relationships.
May need to repeat
during the investigation.
Medium Range Photography
They should still show
some overall
reference features.
They should show
more detail than
overall.
Scales and placards
might be included.
Close-up Photography
A tripod and remote shutter
release are preferred.
A 50m lens and diopters is an
inexpensive method.
Sequence diopters, 4 +2 +1
Focusing is crucial. Rough focus
and then move the camera to the
object.
For cameras with adjustable lens,
set the lens to the widest angle,
activate the close-up icon, move
the camera to the object.
Always include one image with a
scale for all impressions, bullet
holes and bloodstains.
Side Lighting Photography
Tripod and remote flash cord
are preferred.
For tire track and footwear
impressions take photos with
the flash held at 30 – 45
degrees, and held at 12.00,
1:30. 3:00, 4:30 and 6:00 on
the clock dial.
Bracket photos
Focus and depth of field can
be crucial.
Painting with flashlight can
work – especially with digital.
Soft Lighting & Bounce Photography
May be used when other
lighting methods “burn
out” the image.
Bounce may be from an
object, ceiling, wall, and
so forth.
Soft lighting can be
diffused lighting –
through a screen or thin
paper.
Soft light may be with
flashlight.
Time Exposure
Most often used with
Luminol, Fluorescent, and
Alternate Light Sources.
Tripod and remote shutter
release are preferred.
With Luminol, an f2.0 and
45 second exposure are
standard.
Bracket all time exposures.
Painting With Light
A tripod and remote shutter
release are required.
Use a mid range f-stop (8 to
5.6).
Set shutter speed on “B”, or
use camera timer with digital
and automatic cameras.
Open shutter and lock, and
walk to side, flashing every 15’.
(May cover shutter, uncover
with each flash, recover).
Set flash on 40’, f/8.
May use spotlight (?).
Fluorescent Photography
Usually requires tripod,
remote shutter release, and
barrier filter with standard
35mm camera.
Orange 18 is good all around
filter.
A digital camera with barrier
filter for real time photos. This
work with Fluorescein!
May require close-up
techniques.
Filters in Forensic Photography
Alternate Light Sources and
Fluorescent photos may require
filters.
The photo in the previous slide
was taken with a #18 orange
filter.
A polarizing filter may be
necessary to take photos
through water or glass. They
help reduce reflection and glare.
Fill Flash Photography
This is most often done to
lighten a darkened area.
It can be done in the same
manner as painting with
light, but with a much faster
shutter speed in daylight.
The photo at right is a
Luminol photo, f 2.0, two
minute exposure, then
bounce flash from the
ceiling of the shower to fill
in the shower area after the
two minute exposure.
Special Techniques - Snow
Photographing at night, in snow,
can present special problems.
Soft light suing MagLites is a
possibility.
Lightly dusting the impression
with a “dry” fingerprint brush is
an alternative.
Follow local policy on dusting
impressions – photo first without
dust.
Painting with light is another
technique – especially with
digital.
Fire Scenes
Fires may leave numerous
obvious and subtle patterns.
Fire damage may leave a very
dark scene overall, with bright
spots.
It is very important to bracket
photos at fire scenes.
Consider enhancing flash
settings by one stop or more.
Fire scenes usually require
more light than other scenes
due to the absorption of light
by the dark surfaces.
Specific Scene Considerations.
Photograph a persons face and the injuries in
domestic violence, assault and other crimes of
violence.
Fill flash in damaged shaded areas in vehicle
accidents, and objects of interest in shaded areas
in other scenes.
Photo entry and exit in scenes.
Increase the light at fire scenes.
Include at least one photo or image with a scale
for all impressions, bullet holes, and bloodstains
and trace evidence.
Conclusion
Take exit photos.
Inventory your equipment.
Secure your recording medium and mark for chain
of custody.
Enhance images from copies.
Record enhancement techniques step-by step.
Establish throughout the photography process
where you were at and where it was at – this
usually requires noting times and dates.
Prepare appropriate photography narrative reports.