By: Caroleann Fusco, Issue: December 2007/January, 2008

With rapid development in the technology field, it’s difficult for a forensic photographer to choose the right camera and equipment.

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 camera.

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.

Flexibility
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 element.
• 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.

Ruggedness
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.

Resolution
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.

Sensors

• CCD (charged-coupled device)
  The CCD is currently the most common type of digital SLR sensor. Almost every DSLR manufacturer offers at least one CCD-based model.
  Pros: Traditionally, the highest image quality, pixel for pixel. Current sensors include innovative chip architectures designed to enhance dynamic range or speed.
  Cons: Most 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.

Power
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.

External Flash
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.

Optical Viewfinder
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.

File Formats
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.

Pros:

• Can achieve very large reductions in file size; the resulting smaller files take up less drive and media space and transmit much faster.
• Almost universally supported by imaging programs such as browsers. Sorting, viewing, and cataloging are quick and easy.

Cons:

• Produces artifacts and causes loss of detail that may be difficult to notice at low compression ratios but gets progressively worse as compression increases.
• 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 format.

Pros:

• No quality loss.
• Almost universally supported by imaging programs.

Cons:

• 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.

3. Raw
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.

Pros:

• 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.

Cons:

• 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.

Cost:
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 cfusco@penncamera.com. www.penncamera.com.

This 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