What is oblique lighting used for?

Oblique lighting uses a light source positioned at a low angle. Oblique lighting is usually used to show detail by creating shadows on the surface of the evidence. Oblique lighting is commonly used when photographing impressions, tool marks and certain types of fingerprints.

What is oblique light examination?

Illumination of the subject from an angle as opposed to having light shine straight down or up through the object being studied. In microscopy, oblique lighting is at an angle to the optical axis of the system…. Preface. Further Reading.

What is the best lighting for a crime scene?

Available light photography is especially useful for large crime scenes at night when a single flash will not provide adequate coverage. Lighting for the photograph may be from street lamps, parking lot lamps, or even moonlight.

What type of light is used at a crime scene?

Over many decades, visible light sources were used during most searches of crime scenes. Although some forensic investigators would occasionally use ultraviolet (UV Black Light) to examine for crime scene evidence, white light was the mainstay.

What is the best indicator of a mineral’s true color?

Streak is the color of a mineral’s powder. Streak is a more reliable property than color because streak does not vary. Minerals that are the same color may have a different colored streak. Many minerals, such as the quartz in the Figure above, do not have streak.

What is meant by oblique angle?

: an angle that is not 90 degrees : an acute or obtuse angle.

What are the advantages of oblique illumination?

Two main advantages of oblique contrast are that it is a cheap and easy way of improving the contrast of your images. Similarly to Differential Interference Contrast (DIC), images produced using oblique contrast have shadowed regions, giving a pseudo three-dimensional effect.

What are the three basic steps in handwriting analysis?

Terms in this set (16)

• examine the questionable document for detectable traits and record them.
• obtain writing of suspects (exemplar) and compare traits found in the questionable document with it.
• draw conclusions about the authorship of the questionable documents based on the comparison.

What are the 3 types of photographs that need to be taken at a crime scene?

To accomplish this, all crime scene photography consists of three basic types of photographs: overall, mid-range, and close-up.

What are three dimensional impression typically casted with?

Any plastic, or three-dimensional, footwear or tire impressions can be collected by casting. Casting uses a powdered stone material, such as dental stone, that can be mixed with water and poured into the impression. When it dries, this method creates a three-dimensional model of the impression.

Why does blood glow under UV light?

A phosphor converts the energy in the UV radiation from a black light into visible light. For example, body fluids like blood and urine contain these fluorescent molecules and are made visible with the help of a black light.

What are the 2 types of luster?

There are two main types of luster: metallic and nonmetallic. There are several subtypes of nonmetallic luster, namely vitreous, resinous, pearly, greasy, silky, adamantine, dull, and waxy.

How is oblique lighting used in forensic photography?

Oblique lighting is usually used to show detail by creating shadows on the surface of the evidence. Oblique lighting is commonly used when photographing impressions, tool marks and certain types of fingerprints. A very low oblique angle of lighting can be used to photograph dusty footwear impressions and indented writing.

What kind of light is used for forensics?

First, oblique or parallel lighting of a surface such as a floor or carpet with a strong white light (the more powerful the better) will reveal, small particles like hair and fibers for collection. Second, some hair and fibers will also glow under UV or Blue light and will stand out strongly for collection. Bruises/Bite Marks/Pattern Wounds

When to use crime scene and evidence photography?

Crime Scene and Evidence Photography, 2nd Edition © 2014 by Steven Staggs. Crime Scene and Evidence Photography, 2nd Edition is designed for those responsible for photography at the crime scene and in the laboratory. It may be used by law enforcement officers, investigators, crime scene technicians, and forensic scientists.

Where can you find footprints at a crime scene?

Investigators should be aware that footprints may not be readily apparent at a crime scene, and those that do exist may not be on the floor. Footprints can be found on countertops, chairs, or even on victims themselves, both on their clothing or in the form of bruises.