Fusco, Issue: December
With rapid development
in the technology field, it’s
difficult for a forensic photographer
to choose the right camera and
I receive calls daily from forensic photographers in many fields wanting to know
which camera can do it all. I often wish there was an answer to that question
which was simple and direct, but there is no one camera that can do it all. Instead
you should look for the camera that best meets your needs now. As a forensic
photography equipment trainer and integrator, I want to find the equipment that
will give you the best overall performance.
The first step in purchasing
the right camera for your needs is to consider what you will
be capturing. Do you need to make images using UV fluorescence?
How far away from the subject matter will you be located?
What resolution is necessary? How much money do you have to
spend? Answering these questions will lead you to the perfect
As we look at the current market
and the products available, you
have three choices; film, point-and-shoot digital cameras,
and digital SLR cameras. Film is widely known and its quality
is unsurpassed, but it is becoming increasingly unavailable,
and the cost continues to rise with manufacturers producing
less of it. Finding 35mm cameras is also becoming difficult
unless you buy used. With that
said, your choices are digital point-and-shoot or DSLR cameras.
Point-and-shoot style cameras have improved over the past
five years as far as image resolution and specific options,
but they are still very limited. Digital SLR cameras have
become stronger, compact, and affordable.
A camera used for forensic imaging
should have the ability to be
versatile in all possible applications.
Additionally, the days of feeling
that you can’t
get the camera you need due to
cost have passed. Pricing has
been reduced significantly since digital cameras were introduced
into the marketplace. Using a Digital Single Lens Reflect camera
(DSLR) will offer you the ability to change lenses based on the
situation to allow you to capture the best possible image.
The term digital SLR is short
for digital single lens reflex;
so named because these types
of cameras use a mirror positioned
behind the camera lens to direct
light toward the viewfinder when you’re composing a photo. When you release
the shutter, the mirror swings quickly out of the way, letting light from the
lens travel straight to the sensor and momentarily blacking out the viewfinder.
The viewfinder in an SLR incorporates a prism – usually a pentaprism – that
flips the incoming image around so that you can see it right-side up, and bounces
it onto the focusing screen where you see it. When you take the features and
resolution of the DSLR camera and put them against the point-and-shoot style
camera there is no doubt what camera rises to the occasion. So, let’s
take a look at DSLR.
With the DSLR cameras, you will
have the greatest flexibility
and will be able to use many
different types of lenses, flashes,
and other accessories. DSLR cameras
have the ability to work with
the manufacturer’s accessories
as well as third party quality
products that are less costly, keeping things affordable.
Different Lens Use
Having the ability to change
lenses based on the situation
you are in is crucial to getting
the best possible images. The
right lens is as important as
the right camera. Basic lens options include wide-angle lens for
capturing an overview of the scene, a macro lens for close-up
and latent captures, and telephotos for distance and surveillance
photography. Point-and-shoot cameras have lenses that are just
too limited for accurate reproduction. DSLR lenses have large
openings and are better designed to capture all available information
as well as available light. The lens and the camera talk to each
other and the end result is the best possible image. Most DSLR
cameras on the market have focusing systems that enable the camera
and lens to perform at their best when working together.
Lens Technology: Focus Systems
- IF (internal/inner focusing)
Traditional lenses get longer
or shorter as you change
focus, while an internal
focus lens makes its adjustments
on the inside. This type
of system in a zoom lens
is called a “true zoom” and
allows the lens to stay in
focus even as you zoom in
or out. By moving one of
the middle or rear lens groups
in front of the lens diaphragm,
you get faster auto focus
and a lighter overall lens.
There is no change in physical
length of the lens body,
which also remains quite
small. Other benefits include
shorter minimum focus distances
and a non-rotating front
- Extension Focus System
Most entry-level and some professional
lenses use extension focus. All groups or the front group(s)
are shifted for focusing. The physical length changes, usually
during focusing and zooming, often combined with a rotating
front element. Relatively slow AF with long and heavy lenses;
these lenses have relatively slow apertures and more limited
minimum focus distances.
DSLR cameras lend themselves
to more vigorous applications and can stand up to rugged terrain
better than the small point-and-shoot models. The DSLR is also
rated to perform for a longer period of time than a point-and-shoot
camera, therefore making it a sound investment for the department.
DSLR cameras’ image resolution
is far superior to that of
the point-and-shoot style camera.
The image sensor in a DSLR
is larger. This means an 8mp
DSLR and an 8mp point-and-shoot
camera are NOT equal and the
larger DSLR sensor can capture
more information for a better
overall image. The sensor in
a DSLR camera is designed to
replicate 35mm film. The size
of the chip will mean that
when the user is looking through
the lens he or she will actually
be able to capture all the
information that can be seen
through the lens. This is crucial
to a forensic photographer
who wants to capture all the
information accurately the
first time. The image sensor
in a DSLR is larger, giving
the user better depth of field,
contrast, and true color rendition,
all very important elements
when trying to accurately capture
a forensic image.
- CCD (charged-coupled
The CCD is currently the most
common type of digital SLR
sensor. Almost every DSLR manufacturer
offers at least one CCD-based
the highest image quality,
pixel for pixel. Current sensors
include innovative chip architectures
designed to enhance dynamic
range or speed.
expensive; most power-hungry.
- CMOS (complementary metal-oxide semiconductor)
Initial implementations took
advantage of CMOS’ on-chip electronics to make cheap
but noisy sensors. Stripping off the extra circuits increased
each pixel's light-collecting area, thereby boosting sensitivity
and quality to surpass that of many CCD’s.
Pros: Theoretically, lower production cost.
Uses less power than CCD.
Cons: CMOS sensors tend to be bigger than their
CCD equivalents, resulting in larger cameras.
We do not see a significant difference between these two sensors,
when choosing a camera, use other features to make your decision.
Having the ability to shoot long
hours with flash and lens is
an additional benefit to the forensic photographer. Most DSLR
cameras come with rechargeable batteries that can last up to four
hours without flash and up to two and a half with flash usage.
Most point-and-shoot cameras need to be recharged or batteries
replaced after only 40-60 shots. Some of the DSLR cameras also
have a battery grip that is designed to hold multiple batteries
for longer field/lab imaging; this is a great feature that can
make working on a forensic project more successful.
Many imaging situations have
an added challenge, which is
lighting. Most point-and-shoot
cameras have an on-board flash, which is only useful for about
ten feet and in total darkness, much less. Using an external flash
in low light situations as well as situations where there is fluorescent
and tungsten light, will enable the photographer to capture a
better image with clarity and detail.
DSLR cameras have an Optical
Viewfinder. This enables the
user to actually see what he
or she is really going to capture.
Having to hold the camera away from your body to look at an LCD
screen can cause movement and blurred images. Use of the Optical
Viewfinder will ensure quality images are captured.
Some newer DSLR models incorporate
a Live View mode, which allows
the photographer to use the LCD
to compose shots the same way
you can with a snapshot camera. These modes generally lock up
the mirror, with the prism diverting the image to a small sensor
that feeds through to the LCD rather than to the capture sensor.
This does tend to hurt performance, however, and you usually must
focus manually when in Live View mode.
Most of today’s DSLR cameras
have the ability to capture in
multiple formats. The ability
to shoot in RAW, JPEG, and TIFF
can be advantageous to a photographer
as well. This feature will enable
the photographer to capture images
at high resolutions, but then
store them in a smaller format
so they do not take up large
amounts of space. Having the
large file to print with and
the smaller file to email or
store is a great advantage to
high-resolution image capture.
Most standard digicams capture
pictures in JPEG format only,
but digital SLRs give you more
choices. Here’s a rundown
of three important file formats:
1. JPEG: A lossy, compressed file
format. Lossy means that actual image
data is discarded to increase
the compression ratio.
- Can achieve very large reductions
in file size; the resulting
smaller files take up less
drive and media space and transmit
- Almost universally supported by imaging programs such as browsers.
Sorting, viewing, and cataloging are quick and easy.
- Produces artifacts and causes
loss of detail that may be
difficult to notice at low
compression ratios but gets
progressively worse as compression
- JPEGs are finished RGB images, meaning you have limited ability
to alter or reverse the effects of in-camera settings such as
white balance, tone curve, or sharpening.
2. TIFF: An uncompressed, finished RGB file
- No quality loss.
- Almost universally supported by imaging programs.
- Files are many times larger
than even low-compression JPEGs.
- TIFFs are finished RGB images, meaning you have limited ability
to alter or reverse the effects of in-camera settings such as
white balance, tone curve, or sharpening.
Raw files are the photographer’s power tool; it’s
hard to overemphasize just how
powerful they are. Raw files are minimally processed data from the sensor,
which you convert to finished RGB images using special software on your computer.
- Highest potential image quality.
- Depending on your raw-conversion program, you can make extensive
changes to image parameters such as exposure, white balance,
tone curve, and sharpening.
- Typically about one-third the size of an RGB TIFF but with
none of the information loss of a JPEG.
- Images are unfinished, so they need to be converted to another format
for printing and posting on the
Web, which is often a time-consuming process.
- Raw formats are proprietary and usually camera-specific and are often
not supported by image editors
and other software.
Only five years ago, a DSLR package
would have cost $2,000; now, you can get a complete system with
lens for under $600. The cost of the DSLR camera is similar to
the cost of the newer point-and-shoot style cameras, so why settle
for poor-quality images?
With all the developments in
digital photography, it is clear
that a DSLR camera is a versatile yet affordable piece of
equipment that will allow your department to continue their
fight against crime, one photo at a time.
Caroleann Fusco is a Sr. Law Enforcement Specialist with Penn Camera Professional.
Caroleann has a BA in Business and is a Graduate of RPI Digital Imaging for
Law Enforcement program. Prior to joining Penn Camera, she was with a smaller
company where she worked with Law Enforcement agencies for over 12 years. Penn
Camera and its staff were awarded dealer of the year in 2007 by Photo Reporter.
Caroleann can be reached at firstname.lastname@example.org. www.penncamera.com.
article originally appeared in the December 2007/January, 2008
Forensic Magazine and reprinted
with the permission of the
Forensic Magazine and Caroleann Fusco.
Click here to view original
article in the Forensic Magazine