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Created: May 19, 2009
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bridging science
and parascience

This is primarily a glossary of terms, qualified as they directly apply to purchasing video equipment. There is no universal good / better / best in video equipment as far as we're concerned. However, with a little bit of knowledge, you can balance the different aspects of video equipment to find the best combination of portability, quality, and price for the situations you are most likely to find yourself in. Although we frequently make recommendations here, those recommendations only really apply to how we use the equipment at the KRI.

Scenic Theater investigation

Also, much of the information provided here is equally applicable to still cameras. However, we don't include still photography in this guide because we don't recommend digital or electronic equipment for still imaging. It may be quite some time yet before the quality of still photographs captured digitally can compete with the quality of film.


How EVE works:

Light is focused through a lens onto a compact array of sensors. The sensor pack converts light energy into electrical energy, which is then recorded on some form of media. This means there are three basic processes that need to be evaluated to achieve the best possible image captures: Optics (getting the light to the sensor pack), Transduction (converting light to electricity), and Storage (how the camera makes the electrical data readable later). Any additional steps (transmission, processing, conversions, etc.) increase error in varying degrees.

Film-based equipment is capable of much better quality than even the best electronic equipment available. Film cameras eliminate one of the steps of EVE by converting light into chemical patterns directly onto its storage media, thus cutting out an entire range of possible errors. However, the price for quality equipment gets extreme very quickly. At the normal consumer level, it is far more cost effective to work with electronic equipment.

Television studio equipment works a little differently than consumer EVE and is of excellent quality, but is also extremely expensive and often not easily portable.


Transduction properties:

Transduction is the basic element in video equipment. It is the only step that cannot be easily modified, so upgrade is only practical through equipment replacement.

Digital versus Analog: Technically speaking, there is no such thing as a purely digital sensor. Digitization of the sensor pack's signal takes place somewhere between transduction and storage. Digital versus analog is more fully discussed under Storage.


Sensor Types:
CMOS

CMOS: Complimentary Metal Oxide Semiconductors (CMOS) are very inexpensive. They are very high speed, very compact, run cooler, and use less power. However, they aren't particularly scalable (they have size limitations), have lower resolving capabilities (lines of resolution, and separation between lines), and lower light sensitivity than alternative sensor arrays. They are primarily used in cell phone cameras and older CCTV (Closed Circuit Television). Avoid using CMOS-based equipment whenever possible. The loss of image quality is obvious even to the most untrained eye, and that kind of performance loss is just not worth the money. However, engineers are working on CMOS's shortcomings, and CMOS arrays are improving every day.

Fuji CCD

CCD: Charge Coupled Devices (CCD) are relatively affordable and a good balance between price and quality. Technically, CCD is how information is read off the sensor pack, not the pack itself, but the use of the phrase is so common the additional meaning is universally implied. The two major producers of CCD are SONY and Sharp, and their arrays are used in equipment manufactured under most brand names. There doesn't seem to be a significant quality difference between the two companies, but SONY (especially their older sensors) may have better conversion capabilities of certain bands in the infrared (IR) spectrum - vital in night vision use. As yet untested by us is Fuji's range of CCDs, including their "Super CCD."


Night Vision capabilities:

Both CMOS and CCD can encode IR information, but CCD technology outperforms CMOS in this respect also. There is very little price difference between night vision and visible spectrum cameras, so we recommend purchasing night vision capabilities whenever possible. Most night vision cameras can capture both for the same price. More information specifically addressing night vision will be added later, in a separate article. However, much of the information here applies there as well.

Ironically, both SONY and Sharp CCD sensor packs capture IR data, but filter the information out before converting it for storage. Most inexpensive night vision cameras use the SONY and Sharp chips without the filters, or instead filter out the bands of visible light. Early SONY Nightshot cameras picked up a very wide IR spectrum, including a bandwidth of IR which has limited penetrating capabilities - when used in intense daylight or enhanced IR environments, it could "see through" certain colors and types of fabric. These cameras were pulled from store shelves in August, 1998, and IR drop filters were installed. These mechanical filters are easily bypassed, but the new SONY chips have programmed filters which cannot be overridden by most users. Should you find yourself equipped with one of the early sensors, we strongly advise cautioning all members of your investigative team of the camera's capabilities, and recommend they wear loose clothing of average or thicker density, and avoid wearing very dark colors. Always, however, advise your people to avoid wearing white also. White affects some of the automatic controls (gain adjustment) in many cameras, and could reduce image quality substantially. Further, it may be advisable to actually test specific articles of clothing because IR doesn't reflect the same way visible light does, so you may be surprised by which specific articles of clothing will appear white through Night Vision. Any clothing that appears white is undesirable, as it affects the camera's automatic gain features.


Sensor size:

CCD sensors come in a variety of sizes. Most consumer level equipment, however, comes as either 1/4" or 1/3". Obviously, the 1/3" sensor is recommended (bigger is definitely better here). There are some surveillance cameras used in industry that use 1/2" arrays, but price climbs dramatically. Professional equipment using still larger sensors are available, but are not cost effective - easily costing more than $5,000 for a used camera, and can go as far as 20 times that figure for new equipment. Further, advance in high definition are generating series' of densely packed "Super-CCDs from most manufacturers, creating another specification requiring review.


Resolution:

How well a CCD can resolve an image is based on its size and the scanning ability of the camera. The camera reads a line of "charges" (the variations in light across the CCD) from left to right then moves down to the next line and does it again and again until it's read the entire face of the CCD. As it reads the CCD, it sends the data to processing and storage as a frame (also called a raster or image). The number of lines per frame determines how clear the picture can be. The analog television standard is 525 lines per frame (maximum) while DVD standards range from 352 (poor quality) to 720 (excellent quality) lines per frame, although most cabling (transmission) systems limit to a much lower resolution. Once "digitized," each line also can contain different numbers of individual pixels, usually from 240 to 480 (TV) or as high as 1280 (HDTV). The larger the numbers of pixels per line, the more distinct images can be.

Resolution example

The number of frames per second - the frame rate (fps or ips) - is also a very important specification of a video camera. Motion pictures and video don't actually move. They flash a series of still pictures on the screen so fast the mind perceives them as continuous motion. The faster the still images are replaced, the smoother the motion appears to be. The television standard in the US is 30 fps while film cameras operate at 24 fps. Television further smooths apparent motion through a process called interlacing, but this is very rare in consumer level equipment. Interlacing takes advantage of an optical illusion and doesn't contain any more information than non-interlaced video; it just looks smoother. Also, there is a slight flicker introduced by interlacing that tends to disrupt fine images. You can usually see this flicker by watching movie credits as they scroll by on an interlaced system.

Resolution and frame rate are also important specifications with regard to image storage. Some cameras capture images better and faster than its storage system can handle. This becomes particularly important when putting together a CCTV video system, which will be considered in a separate article.


Optical properties:

Optics will be covered in greater detail in an article about still photography, but here are a few "rules of thumb":

The most important easily identifiable aspect of optics is lens size. Bigger is often better. Larger lenses capture and focus more incoming light onto the sensor pack. This is particularly important in low light situations. Some video cameras allow for interchangeable lenses, but this is by no means a standard practice. Equipment can be modified by particularly handy individuals, but optics must be very precisely aligned. Even a slight misadjustment can cause serious visual flaws in captured images. Cameras that are designed for lens interchangeability often have optional special purpose lenses (wide angle, macro, etc.) available, but most portable video equipment does these things electronically. Further, imperfections in smaller lenses create more pronounced image distortion than in larger lenses. For illustrative purposes (the math is more complex than this), a 1 mm scratch in a 3 mm lens affects the image quality 9 times more than the same size defect would affect an image produced by a 9 mm lens.

Size, however, isn't always a good thing, particularly with regard to CCTV. Some manufacturers use the size of a lens to capture narrower fields of vision at greater range rather than taking advantage of the increased amount of light they provide at shorter ranges. With regard to investigating indoor sites, this can be a very serious drawback - you may end up buying a camera that captures a field of vision so narrow as to render the camera nearly useless. As far as I know, there is no way to make this determination by checking lens specifications prior to equipment purchase, except be referring to a (rarely published) "view angle" or "field of vision angle." Half this angle (in degrees) would specify how far from the camera's centerline is being recorded. The difference is in lens geometry, which is hardly ever a part of advertised specs of consumer level equipment. Ideally, large lenses which are advertised as being Wide Angle are the way to go. However, poorly designed wide angle lenses sometimes distort the edges of captured images.

Whenever possible, purchase equipment that lets you adjust optics physically and mechanically. Electronic conversions distort images. This includes "zoom" capabilities. Optical zoom is far more valuable than digital zoom. Optics are an analog process, and are capable of even the slightest fractional variances. Digital, however, rounds fractions, so a digital value is never precisely the value captured by the CCD.

"Name brands" are preferred over unnamed optics. Manufacturers have quality standards, and those standards tend to be more strict when a company has its name on its products. Generic lenses might be just as good, but they might not be good, too. Sometimes flaws are only visible under certain conditions, and could easily be confused for an anomaly. Also, most named brands have threadings which allow the easy addition of optical filters before the lens, such as ultraviolet (UV) filters.


Portability factors:

Portability is a relative term. Completely self-contained handheld video recorders that run on batteries can be started, adjusted, and repositioned almost instantaneously, but there are a number of CCTV systems which set up so easily they are nearly portable. When investigating indoors, a semi-portable system can be more convenient and reliable than most fully portable systems.

Portable and CCTV cameras

CCTV systems are readily available through any number of security and surveillance companies, can be quite reasonable in price, and can provide constant coverage of a wide area - even several rooms simultaneously - over an extended period of time. But no matter how quickly they can be set up, they still require up to half an hour to lay out and interconnect, while a hand-portable unit is recording within seconds. Our recommendation is that if you need to choose one system over the other, go with a self-contained portable unit. If you can do both, however, or if you foresee the need for extended periods of observation, you need to look into CCTV. In fact, our group was using CCTV before we purchased any fully portable units. We'll be addressing the particulars of semi-portable video recording and CCTV in a separate article in the near future.


Storage considerations:

The primary concern here is the question of digital versus analog. In the cases of optics and transduction, we clearly stated that going with analog is recommended. Storage is a bit different. Analog storage of video is primarily done on magnetic tape, and tapes have a very limited lifespan, with imperfections and distortions showing up in tapes in as little as five years. Also, transferring analog data from tape to tape introduces errors, so you can't just keep copying the recordings to a different tape before they go bad. There will be a clear difference between an original recording and third, fourth, and all subsequent generations, and each will get progressively worse. Further, the current analog video standards used in the US - the National Television System Committee (NTSC) standard - is being phased out by the Advanced Television System Committee (ATSC) - digital - standards. In 2009, all broadcast television will be digital capable. Although TVs will likely remain backward compatible for a number of years yet, analog recordings will become progressively more difficult to view.

Analog and Digital

Besides, as far as storage is concerned, digital is far more reliable. It records on media that can last hundreds of years without distortion, and can be copied over and over again precisely. And, with the proliferation of personal computers and the internet, digital has become a necessity. Unfortunately, the current consumer level digital video standards are extremely lossy, so it is vital to store at the highest resolution possible. Technology is working on the digital storage problem incessantly, and has already made great advances (such as Blu-Ray and High Definition technology). If you already have analog equipment, it may be a good idea to convert the original tapes to digital to guarantee your evidence is safely preserved, but hold on to those analog originals in case the improvements to digital over the next few years are sufficient to warrant a re-conversion into the coming upgraded digital formats.

Our only recommendation here is going to have to be vague, and refer generally to the full recording operation: keep the system analog as long as possible. Convert it to the greatest digital resolution possible - you can make lower resolution copies from a high resolution original, but making higher resolution images from low-res originals is a questionable process at best. And store digitally (with back-ups).

A final note: once converted to digital, leave it digital. Converting digital to analog defeats the benefits of analog recording, as the digitization process has already rounded the analog values. Once those values are rounded you can't go back, and trying to do so will give you the worst of both the analog and digital worlds instead of the best.


Other video equipment considerations:

There are a number of features that cameras can come with, and each has its own advantages and disadvantages. We offer no recommendations as to which is preferable. Each pro and con for each feature must be considered and utilized as you see fit.

For instance, Automatic Image Stabilization is an electronic feature that shifts the recorded image around on the CCD according to the last image's primary features. The good aspect of this is that it captures smoother video. The bad aspect is that it digitally introduces imperfections and distorts video images. Also, image stabilization units tend to make very inefficient use of a sensor pack because they sort of "maintain a reserve" around the central image which could instead be used to make its captures more precise.


Pedestal / Gain:

Pedestal and gain controls are automatic in most consumer level EVE. Pedestal is the relative way the camera sees the darkest object and gain is the way it sees the whitest object. Gain in particular is almost always automatic, because if gain values go out of the equipment's range it could possibly damage it. However, there are two ways a camera can adjust gain: it can hack any luminescence (brightness) value that goes out of range, or it can shift the values of all luminescence until the highest gain value perceived is reduced to within range. Which type of system is used is rarely included in a camera's specifications. Hacked values will create fields of white and the brightest point won't be separately discernable within the field, while value shifting will make all luminescence values appear lower than they really are when a bright object is within the camera's field of view. Manual brightness / contrast controls are essentially the same as pedestal / gain, and neither is particularly superior to the other in a fluid investigation environment.


Storage resolution and format:

Many cameras have different resolution capabilities between what it captures and what it can store, usually referred to as viewing resolution and recording resolution. With self-contained portable units, the lower of the two resolutions is normally the recording resolution. If the two resolutions are different, you can always "line out" the camera to a recorder that has better storage resolution, but then you lose the portability benefits and might as well go with a CCTV system.

Recording format also should be considered. Older digital systems recorded in Audio Video Interleave (.avi) format, but .avi was very inefficient and took up a great deal of storage space. In fact, it was all but obsolete. Recently, however, .avi has become something of a "container" more than a format - internally recording any number of other formats - but that is a very complex topic and will have to be addressed at a later date.

We hope you found this helpful.