Even if a strong light striking the lens does not create obvious evidence of lens flare, it may reduce the contrast of the image.

Assuming you can't easily change your camera position, you'll need a lens shade or lens hood to protect a camera image from offending glare or loss of contrast. Since most lens flare problems are apparent in the video viewfinder, the effect of a lens shade can be observed and checked.

Most zoom lenses have a rudimentary lens shade built in, but it's primarily effective at the wide-angle position. At longer focal lengths, with prime lenses, or when you face conditions such as the church setting shown above, you may need a lens shade such as the one on the left.

Rather than invest in a lens shade, it's easier and cheaper to improvise a lens shade with dull black paper and masking tape, or even shield the lens with your hand. Just zoom the lens to the desired point and then try shading the lens as you would your eyes. Check the viewfinder to make sure that you can't see your efforts appearing at the edge or corner of the frame.

In addition to lens shades, there are a number of other attachments that fit over the front of a camera lens, starting with....

Filters

Glass filters consist of a transparent colored gel sandwiched between two precisely ground and sometimes coated pieces of glass.

Filters can be placed in a circular holder that screws over the end of the camera lens, (as shown here) or inserted into a filter wheel behind the camera lens (to be discussed later).

A type of filter that's much cheaper than a glass filter is the gel. A gel is a small, square or rectangular sheet of optic plastic used in front of the lens in conjunction with a matte box, which will be illustrated later. Among professional videographers, these filter types are referred to as round filters and rectangular filters. 

There are many types of filters. We'll only cover the most commonly used types.
   

Ultraviolet Filters

News photographers often put an ultraviolet filter (UV filter) over the camera lens to protect it from the adverse conditions encountered in ENG (electronic newsgathering) work. A damaged filter is much cheaper to replace than a lens. Protection of this type is particularly important when the camera is used in high winds where dirt or sleet can be blown into the lens.

By screening out ultraviolet light, the filter also slightly enhances image color and contrast and reduces haze in distant scenes. In so doing, the filter also brings the scene being photographed more in line with what the eye sees. Video cameras also tend to be more sensitive to ultra-violet light, which can add a kind of haze to some scenes.

Since UV filters screen out ultra-violet light while not appreciably affecting colors, many videographers keep an ultraviolet filter permanently over the lens of their camera.
   

Using Filters for Major Color Shifts

Although general color correction in a video camera is done through the combination of optical and electronic camera adjustments, it's sometimes desirable to introduce a strong, dominant color into a scene.

For example, when a scene called for a segment shot in a photographic darkroom, one camera operator simulated a red darkroom safelight by placing a dark red glass filter over the camera lens. (Darkrooms haven't used red filter safelights to print pictures for decades, but since most audiences still think they do, directors feel they must support the myth.)

If the camera has an internal white balance sensor, the camera must be color balanced before the filter is placed over the lens or else the white balance system will try to cancel out the effect of the colored filter.

Neutral Density Filters

Sometimes it's desirable to control the amount of light passing through a lens without stopping down the iris (moving to a higher f-stop number). Under bright sunlight conditions you may want to keep a relatively wide f-stop and use selective focus to reduce depth of field. Using this technique you can throw distracting objects in the background and foreground out of focus.

Although using a higher shutter speed is normally the best solution (we'll get to that later), the use of a neutral density or ND filter will achieve the same result. A neutral density filter is a gray filter that reduces light by one or more f-stops without affecting color.

Professional video cameras normally have one or more neutral density filters included in their internal filter wheels. To select a filter you simply rotate it into position behind the lens. The table below shows ND filter grades and the amount of light they subtract.

Even on a bright day a 1.2 ND filter will force the camera iris open enough to allow for creative selective focus effects.

With all that has gone before as a background, we can now turn to the first in a series of modules on the camera and its associated equipment.
  

Camera Imaging Devices 

The very heart of a video camera is its imaging device. The first TV cameras used tubes (shown here).  Some early color cameras had four tubes (for red, blue, green, and luminance). This explains why early color TV cameras weighed more than 200 kilograms (500 pounds) and had to be hauled around in trucks.

An example of one of these cameras, which was used in broadcasting in the 1950s, is shown next to the woman on the right. Note how it compares to one the latest pocket sized cameras (complete with a video recorder) shown in the insert at the bottom of the photo.

The latter camera, and in fact most of today's video cameras, use CCDs (a computer chip called a charged-coupled device.) A typical CCD is shown on the left. (Some cameras now use a CMOS chip, but at this point the distinction is not that important.)

The most common CCD sizes are 1/4 inch, 1/3 inch, 1/2 inch and 2/3 inch (the size of the little box shown near the center of the CCD chip package).

Video Resolution

Video resolution is a measure of the ability of a video camera to reproduce fine detail. The higher the resolution the sharper the picture will look.

The standard NTSC broadcast TV system can potentially produce a picture resolution equal to about 300 lines of horizontal resolution. (This is after it goes through the broadcast process. What you see in a TV control room can be much higher.) CATV, DVD and satellite transmissions as viewed on a home receiver can reach 400 lines of resolution.

Three- to four-hundred lines of resolution equal what viewers with 20-20 vision can see when they watch a TV screen at a normal viewing distance.

"Normal" in this case translates into a viewing distance of about eight times the height of the TV picture. So, if the TV screen were 40 cm (16 inches) high, a so-called 25-inch (64-centimeter) picture, the normal viewing distance would be about 2 meters (10 feet).

HDTV/DTV, with its significantly higher resolution, makes possible both larger screens and closer viewing distances.

Lines of resolution as measured by a test pattern, such as the one shown here, are not to be confused with the horizontal scanning lines in the broadcast TV process— typically 525 and 625—which we discussed earlier.

Although most home TV sets are capable of only 300 or so lines of resolution (and that's on a good day!), TV cameras are capable of much higher resolutions—up to 1,000 lines or more.

And so this question arises: Why bother with high resolution in cameras (with their added costs) when the home TV set can't reproduce this level of sharpness?

Answer: As in most aspects of TV production, the better quality you can start out with the better the quality will be for the TV viewer—even with all the broadcast-related losses.
  

Determining Resolution

Charts that contain squares or wedges of lines on a light background can indicate the limits of sharpness. Within a particular area of one of these resolution charts there are lines that converge, as shown on the left.

Numbers such as 200, 300, etc., appear on the chart next to the corresponding line densities. Note that the illustration here represents the small segment outlined in red in the full test pattern shown above.

By exactly filling the camera viewfinder with the resolution chart and observing the point on the chart where the lines appear to lose definition and blur together, we can establish the limits of resolution.

High-quality NTSC cameras can resolve about 900 lines; HDTV/DTV cameras well over 1,000—well off the chart shown here.

Color Resolution

The resolution we've been discussing is based on the sharpness of the black and white (luminance) component of the TV image. It was discovered early in experiments with color TV that the human eye perceives detail primarily in terms of differences in brightness (luminance differences) and not in terms of color information.

When NTSC color television was developed, an ingenious and highly complex system of adding a lower-resolution color signal to the existing black-and-white signal was devised. Using this system, color information can be added to the existing monochrome signal without having to greatly expand the information carrying capacity of the original black-and-white signal.
  

Minimum Light Levels for Cameras

Television cameras require a certain level of light (target exposure) to produce good-quality video. This light level is measured in foot-candles or lux.

A foot-candle, which is a measure of light intensity from a candle at a distance of one foot (under very specific conditions), is the unit of light intensity often used in the United States (although the term is now being replaced by lux.) The origination of the term "lux" is not known, although it's assumed to refer to lumens (a measure of light power) times ten.

Since we'll refer to both lux and foot-candles throughout these modules, you'll need to know that a foot-candle is equal to about 10 lux. (Actually it's 10.76, but 10 is generally close enough, and it's much easier to use in conversions.)

Although they will produce acceptable pictures under much lower light levels, most professional video cameras require a light level of at least 75 foot-candles (750 lux) to produce the best quality video.

With consumer-type camcorders you will find advertising literature boasting that a particular camera is capable of shooting pictures under less than one lux of light. But, the question arises, "What kind of picture?"

The light falling on a subject from a 60-watt light bulb 3 meters (10 feet) away is about 10 lux.  If you have ever taped anyone under this light level with a consumer-type camera, you know that you can't expect impressive video quality.

Although the EIA standard is in place in the United States to specify minimum quality standards for light levels, adherence to this standard is not mandatory. Since manufacturers know that consumers want cameras that shoot under low light levels, they are reluctant to use the EIA standard and look inferior to a competitor who is not adhering to the standard.

Suffice it to say, if you are in the market for a camera and you don't see the EIA standard specified, you need to check out any low-light level claims.  By just zooming in on the darkest corner of the room and observing details in the darkest areas, you can make a rough comparison of the light sensitivity of different cameras.

At low light levels the iris of a camera must be wide open (at the lowest f-stop number) to allow in the maximum amount of light.  As the light level increases in a scene, the iris of the lens must be stopped down (changed to a higher f-stop number) to maintain the same level of exposure on the camera target.

Under low light conditions video can quickly start to look dark, with a complete loss of detail in the shadow areas. To help compensate, professional cameras have built-in, multi-position, video gain switches that can amplify the video signal in steps from 3 up to about 28 units (generally the units are decibels or dB's).

But, the greater the video gain boost, the greater the loss in picture quality. Specifically, video noise increases and color clarity diminishes.

Still and motion picture cameramen who are used to working with IE/ASA (film speed) exposure indexes, may want to determine the sensitivity index of their video cameras. This information is generally not available from camera manufacturers, but can be determined in 

Night Vision Modules

For situations that require video under very low, night vision modules are available that use electronic light multipliers to amplify the light going through a lens.

The most refined of these can produce clear video at night using only the light from stars (a light level of about 1/100,000 lux). Under conditions of "no light" most of these modules emit their own invisible infrared illumination, which is then translated into a visible image.

In recent years camera operators covering news have found night vision devices useful in covering nighttime stories where any type of artificial lighting would call attention to the camera, and adversely affect the story being covered. 

Camera Mounts

Using a camera tripod can make the difference between professional looking video and a video that screams "amateur at work." Although a tripod may be a hassle to carry and set up, the results can be well worth the effort—especially on large digital and HDTV screens where camera movement on static scenes can make an audience a bit "sea sick."

Exceptions to using a tripod are in news and sports where you must be mobile enough to follow moving subjects, documentary style production where shots are brief and rapid, and subjective camera shots that simulate what a moving subject is seeing. 

In recent years some commercials and dramatic productions have used handheld cameras in scenes as a way of imparting a "fluid," "on-the-go" feeling. (Hand-holding a camera also saves valuable production time--which means money!)  

The award-winning film, Traffic, released in 2001, had many handheld shots designed to impart a "documentary frenzy" to some of the scenes. TV series such as Law & Order also use this approach.  

In the hands of a professional director of photography this effect can work; however, when less experienced videographers attempt to handhold a camera (especially while zooming, panning and tilting) the effect can look amateurish and even make viewers a bit nauseous.

If you examine most exemplary films and video productions you will find solid, steady shots—the kind that are only possible with a solid camera support.

On most tripods the pan and tilt head (which attaches the camera to the tripod) is not meant to be used for smooth panning and tilting while shooting—only to reposition and lock the camera between takes.  And, this may be just as well, given the fact that a cut from one scene to another is faster and generally better than panning, tilting or zooming to new subject matter.

Even so, pans and tilts are commonly seen—especially for following action, for revealing the relationship between objects in a scene, etc. Therefore, many tripods have heads designed to smooth out pan and tilt movements.

The most-used type is the fluid head that adds a uniform resistance to pans and tilts—just enough to smooth out the process. 

Bean Bags

A simple camera "mount" that works in many situations is the bean bag. The photo on the left shows one on the door frame of a car.

The "beans" inside are small round soft plastic balls that can assume the shape of the surface the bag sits on. The top of the bag can adjust to the bottom of a camcorder, providing a degree of camera stability. When used on accommodating surfaces, bean bags can represent a quick approach to getting shots.

Wireless Camera Modules

Although camera operators doing live broadcasts from the field used to have to be "hard wired" to a production truck, today's cameras can be equipped with an RF (radio frequency) transmitter, such as the one shown on the back of this camera. The camera signal is transmitted to the production truck where it appears on a monitor just like any other source of video.

These units are commonly used in awards programs, allowing cameras operators to freely roam throughout the isles to get shots of audience members without the problem of trailing vexatious and hazardous camera cables.

Except for possibly Martians (which at this point are of unknown color), having green skin tones signals a technical problem.

Consumer-type cameras typically have automatic white balance circuitry that continuously monitors the video and attempts to adjust color balance. A sensor on or within the camera averages the light within the scene and automatically adjusts the camera's internal color balance to zero-out any generalized color bias.

As with all automatic circuitry, however, automatic color balance is based on certain assumptions—which may or may not be valid.

In this case of automatic white balance circuitry the assumption is made that when all colors and light sources in the scene are averaged the result will be a neutral (colorless) gray or white (i.e., all colors will "zero out.") Variations from this state are "corrected" by the color balance circuitry.

A problem arises if there are strong, dominant colors in the scene, or (with some cameras) if the camera and the subject matter are illuminated by different light sources.

Automatic color balance circuitry will work reasonably well under the proper conditions; and for the typical videographer with simple equipment this is certainly better than nothing.

But, in the professional realm where consistent color balance is expected, automatic circuitry cannot be relied upon to consistently produce accurate color. In this case this there is no substitute for a knowledgeable camera operator equipped with a white card or white piece of paper. (This has to be the cheapest technical aid in the whole video field!)

White Balancing On a White Card

Since we know from our earlier discussion that red, green, and blue must be present in certain proportions to create white, it's relatively easy to white balance (color balance) a professional camera to produce accurate color.

With the camera zoomed in full frame on a pure white card, the operator can push a white balance button and the camera's chroma channels will be automatically adjusted to produce pure white. The camera in effect says, "Okay, if you say that's white I'll balance my electronics so that it will be white."

Focus is not critical, but the card must be placed full frame within the dominant light source of the scene.

After white balancing your camera, pay particular attention to skin tones. This illustration shows color balance that is too reddish, normal, and too blue (if your computer monitor is correctly adjusted to show these differences).

Whenever the dominant light source in a scene changes in any way, professional cameras must again be white balanced. Going from sunlight to shadow will necessitate white balancing the camera again, as will moving from outside light to inside light. Even the passing of a few hours will result in a slight color shift for the sun.

Not to color balance your camera risks having colors in general (and skin tones in particular) change from scene to scene. This will be particularly bothersome during editing when you attempt to intercut scenes that won't match, and flesh tones annoyingly change with every edit.
  

Lying to Your Camera 

You can also "lie to the camera" during the white balancing process to create interesting effects. A warm-red color bias in a scene can be created by white balancing the camera on a blue card; a blue effect (below) results from color balancing on a yellow card.

In an effort to compensate for the colors presented as "white," the camera's white balance circuitry will push the camera's color balance toward the complement (opposite) of whatever color is in the card.

Through a process called approximate color consistency, the human eye can automatically adjust to color temperature changes in the 2,800 to 5,500K range. (Since daylight color temperature varies, depending on location, time of day, etc., some sources list the standard daylight color temperature as 5,600 or 6,000K.)

If you look at a white piece of paper in sunlight, you should have no trouble verifying that it is white. When you take the same piece of white paper inside under the illumination of a normal incandescent light, it still looks white.

By any scientific measure, however, the paper seen under a standard light bulb is now reflecting much more yellow light. A yellow (2,800 to 3,200K) light falling on a white object creates a yellow object. But, by knowing the paper is white, your mind says, "I know that the paper is white." And so (through approximate color consistency) you unconsciously adjust your internal color balance to make the paper seem white.

In so doing you are able to shift all of the other colors slightly so you also perceive them in their proper perspective.

Although we make such color corrections for "real-world scenes" around us, we tend not to make them when viewing television or color photos. In the latter case, we generally have a color standard within our view (sunlight, an artificial light source, or whatever) that influences our perception.

Since we know that human color perception is quite subjective, it's crucial that we rely on some objective, scientific measure or standard so that video equipment can be accurately and consistently color balanced. That measuring instrument, which was introduced earlier, is the vectors cope.
  

Good Color vs. Real Color

You might assume that television viewers want to see colors reproduced as accurately and faithfully as possible. Studies have shown, however, that color preferences lean toward exaggeration.

Viewers (especially in the United States) prefer to see skin tones healthier than they actually are, as well as grass greener, and the sky bluer. In terms of the vectors cope, this preference does not mean that hues are inaccurate, only that they are "stronger" and more saturated.  Interestingly, color saturation preferences seem to differ in different countries.