Zoom, Pan, and Tilt

A zoom refers to using your camera controls to change the focal length, resulting in a telescope-like magnification of the view. On film cameras operators can choose between motor driven or manual driven zooms. Some filmmakers use camcorders with a smooth-slow zoom, but most produce a more jerky result. The recommendation is to zoom only for a specific purpose such as to emphasise size or to indicate entry. Zooming can be distracting unless it is done for a purpose. Cutting between a series of closer and closer shots (called jump cuts) will be easier to watch and achieves the same effect.

Panning refers to sweeping your camera lens across the scene horizontally, tilting is the same movement vertically. Panning and tilting can be a distracting or even disorienting technique. Pan or tilt only for a specific purpose such as to show size. For example, while a speaker describes a classroom set-up, a cut-away to a slow pan across the room might be appropriate. Never pan or tilt just to change the framing unless you will be able to edit out the pan. Attempting to pan or tilt with a handheld camera or low cost tripod head will lead to a jerky movement which betrays you as a rank amateur. A good tripod head provides an adjustable and constant resistance to movement preventing jerky changes in motion in a horizontal pan or vertical tilt. Even with a good tripod it takes experience to pan and tilt correctly.

Track

Tracking refers to following moving objects within the scene by actually moving the camera at the same rate. This gives the viewer a feeling of walking or riding along beside the camera’s subject. While this is common in professional video, the professional has equipment that you may not. The typical process for tracking involves building something similar to a small railroad track upon which the camera and tripod roll. You can use just about any wheeled object to support your camera for a tracking shot. The best no-budget alternative is to use a porter’s dolly with pneumatic wheels that can be softened to absorb bumps. Another alternative if you are shooting outside, is to use the back of a car which is then pushed by a few camera assistants.

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The best way to determine which camera to use if you don’t own one is to rent or borrow one and do tests. Shoot in situations you are likely to encouter, capture  it, and view the result. If you plan to shoot with additional accessories such as an anamorphic adapter, a dolly, jib arm, follow focus gear, or any equipment you have never used before, rent it too and do a small test. Ask yourself how the camera is to use. Is it easy to adjust and comfortable to hold? Does it deliver sufficient image quality? You want to know everything you can about the camera you’re going to use because you don’t want to waste time on the set when it could be spent for another take or setup. You also don’t want a surprise if gear doesn’t work as intended. It is better to find out before production begins.

Shooting tests are not only about using the gear but also about the image quality. Capture the material you shot and look at it in your NLE or compositing application. Color-correct it and experiment with effects. If you’re happy with the results, you know picked a good camera. Use this time to learn the camera’s control.

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Director of Photography (D.P.)
Camera Operator (C.O.)
First Assistant Cameraman (1st A.C.) (Focus Puller)
Second Assistant Cameraman (2nd A.C.) (Clapper/Loader)
Loader (optional position on larger multicamera productions)

This list is based on a union, big-budget feature film and includes only the basic crew positions. All of the following lists of camera department personnel responsibilities are based on a union, big-budget feature film. Each job is different, so not all of these jobs will be done on every show.

Often when multiple cameras are being used there will be additional Camera Operators and assistants. The responsibilities of these additional crew members are exactly the same as the key members of the camera crew. These additional crew positions are hired on an asneeded basis. Additional crew members hired on a daily basis are often referred to as day players.

Smaller non-union productions most likely will not have the loader position, and often on non-union productions the D.P. also serves as the Camera Operator. Each member of the camera department has specific duties and responsibilities, and each position is related to all the others. While the following lists include the basic responsibilities, each production will be a bit different; therefore what each person does on the production may vary slightly. You must be able to make adjustments based on the type of production you are working on. The important thing to remember is to be flexible and willing to help out in any way, providing you don’t step on anybody’s toes or cross over into another department where your help may not be wanted or welcome. The D.P. is the head of the camera department, and he or she is directly responsible to the Director. This chapter lists the D.P. and the Camera Operator responsibilities. Since this book is primarily about the jobs of Assistant Camera Operators, Chapter 3 covers in detail the responsibilities of the 2nd A.C., and Chapter 4 the responsibilities of the 1st A.C.

Director of Photography

The D.P. is the head of all technical departments on a film crew and is responsible for establishing how the script is translated into visual images based on the director’s request. The D.P. decides which camera, lenses, and film stock will be used for the production. The D.P. hires or recommends the Camera Operator and often also hires or recommends the 1st A.C. In many cases, mostly on non-union productions, the D.P. acts as Camera Operator, so that position will not be a part of the film crew. In hiring the 1st A.C., the D.P. usually bases the decision on past work experience and chooses someone he or she is comfortable working with. If that person is not available, the D.P. may ask for a recommendation from his or her usual 1st A.C. or a recommendation from another D.P. The position of 1st A.C. is very important, and the D.P. wants to have someone who can be trusted and is good at the job.
Because the 1st A.C. works closest with the 2nd A.C., the 1st A.C. usually hires or recommends the 2nd A.C. Again, this is usually based on past working experiences, or on a recommendation of another trusted Camera Assistant.

During shooting, all members of the camera department must work closely together as a team to get the job done. The D.P. decides where the camera is placed for each shot and which lens is to be used. It is up to the Camera Assistants to get the camera set up each time and place all appropriate accessories on the camera for shooting. The D.P. decides how the lights are to be placed for each shot, and once the lights are set, he or she gives the 1st A.C. the correct exposure to be set on the lens for shooting. In addition to working closely with the Camera Assistants, the D.P. works closely with the Camera Operator to
decide the composition for the shot. The D.P. along with the Director, may also decide if there are to be any dolly moves for the shot and when they will take place.

Many D.P.s started their film careers as Camera Assistants, so they should know and understand the requirements of the job. They probably worked a few years each as 2nd A.C. and 1st A.C. Then they may have been a Camera Operator for a few years before finally becoming a D.P. The length of time that is spent at each position is based on each person’s individual circumstances.
There are also many D.P.s who arrived at the position without ever having been a camera assistant. They may have been a Lighting Technician or Gaffer before becoming a D.P. They also could have started their career as a documentary filmmaker or television news cameraperson. If the D.P. has never been a camera assistant, he or she may not be fully aware of all the duties of the job. In any case you must be able to work closely with the DP to get the job done.
Many D.P.s started out working on small, low-budget films, or even some student film projects. These small projects enabled them to gain valuable experience that later helped them get their first big break on a major, big-budget production. Some D.P.s started out as apprentices to well-known D.P.s. By working with these professionals, they learned many valuable skills that helped them when it came time to start out on their own.

The following are many of the responsibilities of the D.P. They are listed in no particular order.

• Reads the script so that he/she understands the story and has an idea of what may be involved in the shooting of the film

• Works with the director, production designer, and set construction supervisor to determine the “look” of the film and how the sets will be designed and constructed

• Assists the Director in translating the screenplay into visual images

• Attends production meetings to discuss the script and make any suggestions to help the production run smoothly

• Goes on location scouts with the Director and any other production personnel to help determine their suitability for filming, both aesthetically and from a practical production standpoint

• Chooses camera, lenses, filters, film stock, and any other camera equipment that may be needed

• Consults with 1st A.C. on any camera equipment or accessories that may be needed

• Recommends the camera rental house to use for renting equipment

• Recommends the grip and lighting equipment rental companies to use for renting equipment

• Recommends the laboratory that will process the film

• Supervises any camera tests that may be necessary or arranges for them to be done

• Supervises any film tests that may be necessary or arranges for them to be done

• Supervises any lighting, costume, and makeup tests or arranges for them to be done

• Hires or recommends the members of the camera crew, the gaffer, and the key grip

• Works closely with the Production Manager or Production Coordinator to determine the size of the camera, grip, and lighting crews

• Works with the grip and electric crews to determine the type and quantity of equipment needed for each department

• Maintains the photographic quality and continuity of the production

• Sets the camera position, camera angle, and any camera movement for each shot based on the Director’s request

• Selects the lens and filter required for each shot

• Determines the correct exposure (t-stop) for each shot

• Works with the Director when lining up and matching action and screen direction from shot to shot

• Works with the Camera Operator to set the composition for each shot based on the Director’s request

• Determines if the shot will require a dolly or crane move

• Plans and supervises the lighting of all scenes, working closely with the Gaffer and the electrical crew

• Maintains the continuity of lighting from scene to scene

• Supervises the crews for all cameras in use on the production

• Supervises each technical crew while on stage or location

• Specifies the laboratory instructions for developing and processing of exposed film

• Views dailies with the Director and other production personnel

• Supervises the color timing of the final print of the film

• Supervises the transfer from film to videotape

• Provides exposure meters and other necessary tools associated with performing the job

Camera Operator (C.O.)

The next person in line in the camera department is the Camera Operator. In the United States, the Camera Operator works closely with the D.P. to determine the composition for each shot as instructed by the director. In Britain, the Director and the Camera Operator work together to determine the placement of the camera and the composition of the shots. In Britain, the D.P., or Lighting Cameraman as he or she is sometimes called, deals primarily with the lighting of the set.
The primary job of the Camera Operator is to make smooth pan and tilt moves in order to maintain the composition of the subject. The Camera Operator keeps the action within the frame lines in order to tell the story. Sometimes the Camera Operator decides the placement of the camera and also chooses the lens for each shot. The 1st A.C. works most closely with the Camera Operator during rehearsals and actual shooting. There may be a complicated camera move that requires zoom lens moves and many focus changes during the shot. The Camera Operator rehearses these moves with the 1st A.C. before shooting them to be sure they are done at the correct time during the shot. If a problem arises with any of these moves during the shot, the Camera Operator is often the only one who can detect it and must let the 1st A.C. know where the problem occurred so that it can be corrected for the next shot.
The Camera Operator rehearses any dolly moves that may have been determined by the D.P. The Camera Operator will sometimes let the dolly grip know when it is the right time to move the dolly during the shot. The Camera Operator also works with the sound department and boom operator to set the placement of the boom microphone during
the shot. He or she may let the boom operator look through the camera to see the frame size, or may just tell the boom operator where the edge of frame is so that the microphone is placed where it is not in the shot. The Camera Operator should tell the 2nd A.C. if any actor’s marks are visible in the frame and if they should be made smaller for the shot. When actual shooting starts, the Camera Operator sometimes instructs the 2nd A.C. where to place the slate so that it is visible in the frame.

The following are many of the responsibilities of the Camera Operator, which are listed in no particular order:

• Reads the script so that he/she understands the story and has an idea of what may be involved in the shooting of the film

• Adjusts the viewfinder diopter for his or her vision

• Adjusts the seat of the dolly for comfort and proper positioning prior to each shot

• Maintains the composition as instructed by the Director or the D.P.

• Watches to make sure the proper eye lines and screen directions are maintained

• Makes smooth pan and tilt moves during each shot to maintain the proper composition

• Approves or disapproves each take after it is shot: certifies that no microphones, lights, stands, or other unwanted items were in the frame

• Works closely with the 1st A.C. to ensure proper focus, zoom moves, and t-stop settings for each shot

• Works closely with the 2nd A.C. regarding the proper size and placement of actors’ marks; if the marks are seen in the shot, the Camera Operator informs the 2nd A.C. to make them smaller or to remove them

• Notifies the 2nd A.C. when the camera has reached sync speed so that he or she may slate the shot

• Works closely with the dolly grip during rehearsals and takes to ensure smooth dolly or crane moves

• Works closely with the sound department to ensure proper placement of microphones during each take by telling them where the edges of the frame are located

• May act as D.P. on any second unit shooting during the production

• Views dailies with the Director and other production personnel

First Assistant Cameraman (1st A.C. or Focus Puller)

• Knows and understands all professional motion picture camera equipment and accessories currently used in the industry

• Reads the script so that he/she is aware of the story and recommends any special equipment that he/she feels may be needed to carry out specific shots

• Works with the D.P. and/or Camera Operator to choose the camera equipment that will be used on the production

• Recommends the 2nd A.C. and Loader/Trainee to the D.P. and/or Production Manager

• Works with the 2nd A.C. to prepare a list of expendables, which is then given to the production office or Production Manager so that the items may be purchased

• Preps the camera package alone or along with the 2nd A.C.; ensures that all equipment is in proper working order

• Responsible for the overall care and maintenance of all camera equipment during production

• Mounts the camera head onto the tripod, dolly, or other support piece and ensures that it is working properly

• Unpacks, assembles, and warms up the camera and all of its components at the start of each shooting day

• Does not leave the camera unattended

• Loads and unloads proper film into the camera for the shots and setups

• Resets the footage counter to zero after each reload

• Resets the buckle switch in the camera if necessary

• Keeps all parts of the camera clean and free from dirt and dust, including camera body, lenses, filters, magazines, and so on

• Oils and lubes the camera as needed

• Sets the viewfinder eyepiece for each key person looking through the camera

• Before each shot, ensures that the camera is level and balanced

• If the camera is mounted on a tripod, ensures that it is securely positioned and leveled

• Checks to be sure that no lights are kicking into the lens, causing a flare, when the camera is in its proper position

• Places proper lens, filter, and any other accessory on the camera as instructed by the D.P. or Camera Operator

• Checks that lenses and filters are clean before filming

• Sets the t-stop on the lens before each take as instructed by the D.P.

• Measures the distances to subjects during rehearsals and marks the lens or focus marking disk

• Checks the depth of field for each shot as needed

• Follows focus and makes zoom lens moves during takes

• Adjusts the shutter angle, t-stop, or camera speed during a take, as needed and as instructed by the D.P.

• Checks that camera is running at correct speed during filming

• Gives the 2nd A.C. footage readings from the camera after each take

• After each printed take or when instructed by the D.P., checks the gate for hairs or emulsion buildup and requests another take if necessary

• Supervises the transportation and moving of all camera equipment between filming locations

• Works with the 2nd A.C. to move the camera to each new position

• Works with the 2nd A.C. to be sure that all camera batteries are kept fully charged and ready for use

• If there is no 2nd A.C. on the production, then also performs those duties

• Orders additional or special camera equipment as needed

• Checks call sheet daily to be sure any additional camera equipment and crew members are requested if needed

• Arranges for the return of any camera equipment no longer needed

• Arranges for the return and replacement of any damaged camera equipment

• Oversees all aspects of the camera department

• Disassembles the camera and its components at the completion of the shooting day and packs them away into the appropriate cases

• At the completion of filming, wraps and cleans all camera equipment for returning to the rental house

• Provides all the necessary tools and accessories associated with performing the job

Second Assistant Cameraman (2nd A.C. or Clapper/Loader)

• Before production, obtains a supply of empty cans, black bags, camera reports, and cores from the lab or asks the Production Manager to arrange this

• Prepares a list of expendables with the 1st A.C.

• Preps the camera package along with the 1st A.C.

• Cleans the camera truck and/or darkroom for use during the production, and ensures that each is loaded with the proper supplies and equipment

• Loads and unloads film in the magazines, and places proper identification on each if there is no loader

• Checks with loader (if there is one) to be sure that all film magazines are loaded and properly labeled

• Checks darkroom to be sure that it is light proof on a daily basis if necessary

• Communicates with the Script Supervisor in order to obtain the scene and take number for each shot, and also which takes are to be printed

• Records all information on the slate

• Records all information on the camera reports

• Checks with Script Supervisor as to what takes are to be printed for each scene

• Helps to set up the camera at the start of each shooting day

• Marks the position of actors during the rehearsals

• Slates each scene, whether sound (sync) or silent (MOS)

• Assists in changing lenses, filters, magazines, and so on, and in moving the camera to each new position

• Sets up and moves video monitor for each new camera setup and makes sure the cable is connected to the film camera

• Prepares exposed film for delivery to the lab and delivers it to the production company representative at the end of each shooting day

• Cans and labels any film recans or short ends

• Serves as camera department contact with production office, film laboratory, and camera equipment rental house

• Maintains a record of all film received, film shot, short ends created, and film on hand at the end of each shooting day during the production

• Maintains an inventory of film stock and expendables on hand and requests additional supplies from the production office as needed

• Maintains an inventory of camera equipment on hand, additional equipment ordered, and any equipment damaged or returned

• Distributes copies of the camera reports and film inventory forms to the appropriate departments

• Keeps a file of all paperwork relating to the camera department during the production: camera reports, daily film inventory forms, processing reports from the lab, equipment packing lists, expendable requests, etc.

• Keeps a record of all hours worked by the camera department and prepares time cards at the end of each day

• Performs the job of 1st A.C., if necessary, in the absence of the 1st A.C. or when additional cameras are used

• Works with the 1st A.C. to move the camera to each new position

• Works with the 1st A.C. to ensure that all camera batteries are kept fully charged and ready for use

• At the end of each shooting day, helps the 1st A.C. pack away all camera equipment in a safe place

• At the completion of filming, helps the 1st A.C. wrap and clean all camera equipment for returning to the rental house

• At the completion of filming, cleans and wraps the camera truck

• Provides all the necessary tools and accessories associated with performing the job

Loader

• Maintains an inventory of all film stock initially received from the production company

• Maintains a record of all film received, film shot, short ends created, and film on hand at the end of each shooting day during the production

• Loads and unloads all film magazines during the course of filming

• Properly labels all loaded film magazines, cans of exposed film and short ends, and recans of unexposed film

• Prepares exposed film for delivery to the lab and delivers it to the production company representative at the end of each shooting day

• Provides all the necessary tools and accessories associated with performing the job

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• Single-chip. These dominate the lower, domestic end of the market. It collects over 300 000 pixel bits of information, which sounds a lot but is considerably less than the three-chip.

• Three-chip. This one is found in any of the better camcorders in the mid and upper ranges. The big difference here is that there are three chips, each gathering 300 000 bits of information, but this time each chip gathers just one colour each: red, green or blue. The single-chip gathers all colours together and so has to squeeze all three groups of information into one chip. The additional quality of the three-chip is worth about an extra 20 per cent in terms of picture and colour resolution.

If you want to make programmes for broadcast then you need to get a three-chip. Most people will not notice the difference between single-chip and three-chip, but broadcasters will notice and do not
accept certain quality of pictures. But if you intend to show only on the web, this difference is going
to be reduced later, so it may not be useful.

At this stage the camera sorts out how much information can be stored and how much has to be
left behind. Mini-DV tapes do not have the capacity to store all the information that a camera
could record but are significantly better than VHS. In terms of a ratio of information kept to that
thrown away, mini-DV is 5:1, compared to 7:1 for analog Hi8 and 15:1 for VHS. How well a camera
squashes down its information is crucial. The new generation of HD cameras have suffered from a
poor compression method. It remains a problem for manufacturers to convince the market about HD
because the recorded picture is so reduced from what it should be, given the huge size of each frame of HD video.

When The Image Gets Recorded onto Tape

Digital tape is much more rugged than that used for analog S-VHS or VHS video. It is made of an
advanced form of Metal Evaporated (ME) tape. It consists of a double-coated magnetic layer, which is in turn coated in tough carbon. This enables stored digital information to be played back with minimal loss of quality and less picture noise, or interference. ‘Bleeding’ from the audio track to the video tracks is also unlikely, further reducing interference.

Solid-state cameras record onto discs but have to use a sophisticated form of compression to enable it to do so. In consumer models images are recorded onto a fixed hard drive or onto DVDs, though the latter have failed to take off in the consumer sector in the way manufacturers would have liked.
Cameras using hard drive recording have become more widely used, possibly a result of the iPod effect, where consumers understand and trust mini hard drives. A further development has been in removable hard drives. For filmmakers using cameras such as the Canon XZ2 or Sony PD170, the favourites of many low-budgeteers, hard drive recording was not possible until large removable 80GB drives such as Holdan’s Firestore made it to industry shows.

The term ‘broadcast quality’ has changed considerably since DV became a consumer  item; in terms of the consumer it has become a loose term and often simply  refers to a quality far above that offered by analog, but not necessarily meeting  broadcast technical quality guidelines. Whatever the publicity blurb says, check  with an independent advisor first before committing yourself to an expensive camera  that claims to be broadcast standard but stops your programmes being accepted  by television companies.

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In contrast to a light bulb’s yellow tint, daylight looks blue. You can sometimes see the difference in mixed lighting situationsif you turn on a lamp at dusk, you may notice the natural light coming in through the windows makes the room look blue, except for the area around the lamp, which looks yellow. Cinematographers describe the difference in terms of color temperature. The concept refers to the range of color a light source emits, and is measured as a temperature in units called Kelvin. At the lower end of the scale, light sources emit more red and yellow light. At the higher end, sources emit more blue light. Daylight at noon on a sunny day measures approximately 5500 k, and tungsten light measures approximately 3400 k. (Tungsten refers to the metal used in the filament in a specific type of bulb used in film and video lighting; other kinds of indoor lighting, such as fluorescents, produce different color temperatures and different lighting tints.)

Each of the lighting types (fluorescents, commonly available household light bulbs, and tungsten production lights) creates a different color cast. In mixed lighting situations, they can be notoriously difficult to work with in combination. If you’re shooting in an indoor location with mixed lighting and your subject moves across the room, he will appear to change color when moving from one area of light to the next. This might look really cool if you’re shooting a music video in a disco, but other than that, it’s a good thing to avoid.

To avoid problems with mixed lighting, filmmakers often turn off all the household light bulbs and any fluorescent lights in a room and rely on their own tungsten lamps to light a shot. Turning off fluorescent lights is an especially good idea, because in addition to making people look green in video, fluorescent lights flicker. The flicker might not be visible to the human eye, but in a video recording, it can look like a strobe effect. Again, if you’re going for a disco look, you’re all set; otherwise, turning off fluorescents is a good habit to get into.

To compensate for differences in color temperature, reels of film are balanced to shoot in daylight or tungsten environments. A filmmaker shooting outside would use a reel of daylight film, and would switch to a reel of tungsten for an indoor shoot. Use the wrong type of film in the wrong lighting, and you’re stuck with discolored images. DV cameras, as you may have noticed, use the same tape regardless of lighting conditions. To compensate for differences in lighting, DV camcorders have a white balance setting.

DV camcorders adjust their color by taking a sample of white area or object in a scene each time the camcorder setup is changed. Because lighting varies from location to location, setting an accurate white value becomes especially importanta bad white balance throws off all the other colors in your image. If you ever looked at a tape and noticed that all the images looked especially yellow or blue, the white balance was probably set incorrectly. Some experienced directors intentionally use a distorted white balance to create a desired effect, most of the time a bad white balance simply means someone behind the camera made a mistake.

The color temperature of indoor lighting varies depending on the type of lights in use, and color temperature outdoors can vary by the time of day (dusk and dawn are lower on the scale than midday). It can even vary in a single scene when the sun goes behind a cloud. Many cameras offer preset white balance modes for outdoor, indoor, and nighttime shots, but the safest way to set a truly accurate white balance is to use your camera’s manual white balance function. If you’re using lights in an indoor location, daylight coming into the room through any windows can create a mixed lighting situation that renders a preset white balance mode useless anyway.

Setting a manual white balance varies from camcorder to camcorder, but the essential action involves zooming in on a flat white object so it fills the frame (you can buy expensive white balance cards or use a white loose-leaf binder, white foam core, illustration board, or even a blank piece of paper) and then pressing a button to set the white balance. This manual function specifically defines what white looks like in a particular lighting situation, and the camera adjusts all the other colors accordingly.

When you’re shooting indoors, a window becomes a light source. Daylight, or natural light, can be very brighteven when you’re inside. Filmmakers often use natural light to their advantage, especially when composing interview shots. If you seat a person near a window, facing the camera, you can use natural light to create an attractive highlight on the side of her face. The parts of a person’s face farther away from the window will fall into shadow, creating a very nice contour effect. If the shadows become too dark, you can set up a light or reflect some daylight to fill them in. Even if using daylight creates a mixed lighting situation, you’ll be okay as long as you set the white balance and as long as your subject stays in the same part of the room.

Source from DV Filmmaking Book

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The Actual Tests
Each camera is aimed at a test chart with its zoom lens adjusted between wide angle
and half-way zoomed in. This achieves respectable light transmission. The chart is
illuminated with 3100 degree Kelvin (3100° K) video lights adjusted to spread the light
evenly over the chart. A digital light meter is used to accurately determine
the illumination of the test chart. The camcorder circuitry is exposed, if necessary,
so that the video signal can be measured directly using a video waveform monitor,
video noise meter, and high resolution video monitor.
The camcorder is switched to its full AUTOMATIC mode for exposure and color balance,
and its GAIN UP control is set to the “normal” position. (The manufacturer is permitted
to perform these tests in the GAIN UP position as long as it indicates in its specifications
that this position was used during the test). The camera is manually focused and set
to 1/60 second shutter speed. The electronic image stabilization circuits are switched
off, the digital zoom is switched off, the on-screen display (OSD) feature is switched
off, the RF adapter (TV channel 3/4) bypassed, and of course, any built-in accessory
lights are deactivated.

Test 1 Luminance Level
The camera is aimed at a logarithmic gray scale chart (a chart with two horizontal rows
of eleven progressively darker gray bars and a white bar in the center) and illuminated
to 1000 lux, as measured with a digital light meter. Under normal light, the white chip
will appear white on a TV monitor and will trace a plateau at 100 IRE on the waveform
monitor scale, representing pure white. The progression of darker bars appear as
stairsteps on the waveform monitor, with the bottom step at about 7 IRE. The light
level on the chart is then reduced. As this happens, the TV monitor picture gets darker
and the trace on the waveform monitor gets lower. Eventually, the trace that
represented the white bar only reaches 50 IRE, the cutoff point. Put another way,
when white things look 50% white (50 IRE), experts consider the picture to have
minimum acceptable brightness. The technician, fumbling in the dark, locates his light
meter and takes another lux reading.

Test 2 Black Level
The darkest bar on the chart is 2% white and appears as a black bar on the TV monitor.
On the waveform monitor the signal makes a trace at approximately 7 IRE on the scale. Cameras measuring below 4 or above 10 on the scale for black level do not qualify for
further testing (these cameras, since they are not making correct black, cannot have
whites that are trustworthy).

Test 3 Luminance Signal-to-Noise
Next the gray scale chart is removed and an 18% gray card is put in its place.
The camera now sees nothing but dark gray. The video noise meter then measures
the video signal and a calculation is made which determines the signal-to-noise ratio.
If the S/N ratio is 17 dB or greater, the picture is considered acceptable. Incidentally,
the lower the S/N ratio, the grainier your picture, and a number below 17 represents a
picture that is quite snowy. Remember earlier how professional TV cameras sported
S/N ratios around 63 dB? That’s one reason why professional video looks so good
compared to what the rest of us make at home.

Test 4 Chroma Level
The gray chart is then removed and replaced with a Macbeth color checker chart,
a chart with little colored squares. The chart is illuminated to 1000 lux and the chroma
signal (the color part of the video signal, the C in Y/C signal) is sent to the waveform
monitor. The waveform monitor is adjusted so that it measures just one square,
the pure red square on the chart. The technician notes the signal level of the red
square and then decreases the illumination down to where it was set earlier in test
number one. With less light, the chroma signal becomes weaker on the waveform
monitor. The minimal acceptable chroma level for the red square with low light is
25% of the chroma level when the red square was fully illuminated.

Test 5 Resolution
A test pattern with converging thin lines replaces the previous chart and the
illumination is cranked back up to 1000 lux. Where the lines are far apart, they are
easy to see on a TV monitor. Where they are close together, they merge into
gray mush. At some point the technician can tell where the lines are so close together
they just begin to comingle. Numbers on the chart tell what resolution that part of
the chart represents, so the technician just reads the numbers off the chart.
Next the illumination is decreased to the low light level determined in step number one
and the technician again checks for where the lines blend together and reads the new resolution numbers off the chart. These new numbers must be 70% of the value
he/she read at full brightness.
If the camcorder passes all of the above tests, then the light meter readings in step 1
can be used as the minimum lux ratings for the camera. If the camcorder does not meet
all of the minimum performance levels in tests 3, 4, and 5, then the illumination level
must be increased in step 1 and the whole process repeated. Eventually it is possible
to apply enough light so that the camcorder passes the minimum requirements of each
test, and that chart illumination level is the one used to describe the camera. This may
seem like a lot of technobabble, but now you know how honest light sensitivity
measurements are made. Thanks to the EIA and the participating manufacturers,
buying a camcorder just got easier for those consumers who know to look in the specs
for low light sensitivity “measured by the EIA Standard”.

Dr. Peter Utz

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