Forensi-Tech Limited
Box 40007 Bank & Hunt Club - Ottawa, ON, Canada - K1V 0W8
Phone: (613) 737-5200 Toll-Free: (866) 860-8179 Fax: (613) 521-2512
E-mail: [email protected] Website: www.forensi-tech.com
Technical
Note
Fluorescence Photography
Theory
Photography of latent prints developed with fluorescent powders or dyes is not really different from
photography with a strobe light unit or sunlight. The four elements of photography (film, light, aperture,
and shutter) are still the same. The only difference is the type of light being used. Remember the
photographer’s adage, “if you can see it, you can photograph it.”
The latent fingerprint which is fluorescing with the use of a forensic light source is viewed through filtered
goggles; therefore, to take the picture, the same color filter must also be used on the camera. For example,
if red goggles and the 570 nm wavelength setting on the Forensic Light Source show the best contrast latent
print, a red filter on the camera and the 570 nm wavelength setting on the Forensic Light Source should
also be used to take the photograph.
Camera Equipment
In the laboratory, cameras on a copy stand can be used, e.g., Polaroid MP-4 Plus. These cameras have the
advantage of using large format lm to be able to photograph a whole palm or several fingers on the same
sheet of film in a one-to-one size. In the field, the most convenient and versatile camera to use is a 35 mm
format camera. Regular crime scene photography can be done using this camera and, on the same roll of
film, take photos of the latent prints. The latent prints should be photographed one-to-one or life size. If
your 35 mm camera lens does not focus at 1:1, an adapter can be attached to produce a 1:1 negative.
Because the exposures can be lengthy, a tripod is a necessary piece of equipment. The 1:1 lens adapter by
Lightning Powder Company, Inc. can be used as a mini-tripod. Auto-focus cameras should be set for
manual focus. A cable release is handy to avoid camera movement. For a larger format of 31/4" x 41/4", the
Polaroid Spectra Law Enforcement Kit is an easy-to-use camera for this type of photography in the field.
The Spectra camera fits on to a one-to-one copy stand which can be held against a wall or placed on any
other surface or object.
Camera Filters
It is recommended that a set of three filters (orange, red and yellow) be obtained. In a pinch, a pair of
goggles can be placed over the lens of the camera. We have found that the following commercially available lters give good results: Nikon 056 = orange, Wratten 29 = red and Wratten 15 = yellow. Quality
filters from other manufacturers should also be acceptable. No filters are needed if a long wavelength
ultraviolet setting is being used.
Film
Most types of films used for general crime scene photography can be used for fluorescence photography.
It is not necessary to remove the partial roll from the camera while shooting a crime scene to change to a
special roll of film. Black and white, panchromatic film or color slide or color negative films can be used.
No special darkroom processing is needed. Polaroid slide films work very well in crime scene situations
because they can be processed immediately at the scene to examine the results. Any brand of slide film is
beneficial in fluorescence photography as it can be printed on regular black and white photo paper and the
resulting latent prints will be black in color on a light colored background.
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Exposure
As with any close-up photography, a medium to small ƒ/stop should be used. Suggested ƒ/stops are ƒ/11 or
ƒ/16. The shutter will be set on “B” for bulb or on “Auto,” if using an aperture-priority automatic camera.
When using the manual setting of “B,” knowledge of an appropriate time exposure is needed. Some
experimentation before going to a crime scene is necessary. Even at the crime scene, it is wise to bracket
the exposures. For example, using an Omnichrome® OP-1000a forensic light source set at 485 nm, with
Blitz-Red™ and Blitz-Green™ fluorescent magnetic powders, an orange viewing filter and an orange filter
(Nikon 056) on the camera, an Olympus OM-2N with a 50 mm lens, a Lightning 1:1 lens adapter and
Polaroid Polapan slide film (ASA 125), an excellent exposure was produced at 5 seconds at ƒ/16 (see
photograph below). We bracketed the exposure at 2 and 8 seconds.
We also tried using the automatic exposure mode of the camera and achieved excellent results at ƒ/11 and
ƒ/16. We repeated the exposures using Ilford XP2 black and white film (ASA 400) with outstanding results.
The automatic mode of the camera gave the most consistent exposures. A suggested starting exposure is
ƒ/16 at 2 seconds. Remember, negative film must be reversed if black ridges for the latent print are desired.
An example of Polaroid Polapan slide film printed on Kodak
Polycontrast Rapid II RC black and white photo paper. The
latent print on the left was developed with Blitz-Green™
fluorescent magnetic powder and the one on the right was
developed with Blitz-Red™ fluorescent magnetic powder.
Scales
It is always wise to include a scale in the
photograph, even when using a 1:1 lens or
1:1 lens adapter. If challenged to its accuracy, the photograph can be proven to be the correct size by
checking the scale. We suggest our 20 mm scales, as they are not too big to be included in a 1:1 photograph. It is always a bit difficult to squeeze a large ruler or scale into the picture and determine whether the
lines are inches or millimeters. If the 20 mm scales are consistently used for all 1:1 photography, there is no
question as to whether the lines are inches or millimeters.
Additional Reading
Fingerprint Detection by Fluorescence Examination: A Guide to Operational Implementation by the
Police Scientific Development Branch of the British Home Office
Close-up & Macro Photography for Evidence Technicians by James A. McDonald
An Introduction to Lasers, Forensic Lights and Fluorescent Fingerprint Detection Techniques by Dr. E.
Roland Menzel
Ordering Information
Catalog No. 6-2049 .......... Lightning 1:1 Lens Adapter for 49 mm diameter lens
Catalog No. 6-2052 .......... Lightning 1:1 Lens Adapter for 52 mm diameter lens
Catalog No. 6-2055 .......... Lightning 1:1 Lens Adapter for 55 mm diameter lens
Catalog No. 6-3820 .......... 20 mm Scales, roll of 150
Catalog No. 6-3847 .......... Adhesive Fluorescent Scales, 2 in—50 mm, pack of 50
Catalog No. 6-3816 .......... 6 inch Fluorescent Scales, cardstock, pack of 10
Catalog No. 6-3885 .......... INCH "L" Shaped Scale, Fluorescent, cardstock, pack of 5
Catalog No. 8-5039 .......... HOME OFFICE/Fingerprint Detection by Fluorescence Examination
Catalog No. 8-5046 .......... McDONALD/Close-up & Macro Photography
Catalog No. 8-5043 .......... MENZEL/Intro to Lasers, Forensic Lights & Fluorescent Fingerprint Detection
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Please Note
The goal of latent print examiners and technicians is to discover and collect latent prints by various means.
The ultimate goal is to identify those latent prints to the person responsible for the criminal act and prosecute them to the fullest extent of the law. Some of these means to develop latent prints include processing
evidence and other surfaces using powders, chemicals and lighting techniques. The purpose of this booklet
is to provide a resource of information about latent print processing techniques. This booklet does not
contain every process available and does not claim to be all inclusive of all variations of processes. The
information has been collected from various sources.
Caution
This booklet contains descriptions of processes utilizing chemicals or combinations of chemicals which
may be hazardous to the user’s health. It is strongly recommended that proper precautions be taken when
using hazardous chemicals or combinations thereof. Safety equipment needed may include fume hoods,
gloves, protective clothing, safety goggles, splash shields or respirators. It may be necessary to store these
chemicals in specific containers or cabinets. It is the user’s responsibility to know and use the proper and
adequate safety equipment required for the various chemicals listed.
Disclaimer
FORENSI-TECH LIMITED assumes no responsibility for the use or misuse of any of the chemicals,
procedures, methods or ideas described herein resulting in injury and/or damage to persons or property.
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