Chapter 8
TV Monitors And Video Projectors
TV MONITORS What's a Monitor?
The display element in the video system is of course the VIDEO MONITOR. Originally, a true video monitor was a must for any VTR playback, but since video has made substantial inroads into consumer and institutional marketplaces, TV RECEIVERS and MONITOR/RECEIVERS are now widely used with video equipment.
The true video monitor plays back picture only—no sound. The standard of the broadcast industry is the CON RAC monitor which sells for about $5,000 for a 19-inch diagonally measured color monitor with all the "bells and whistles." Since these little gems are a bit expensive for the average video user and too complex and specialized to be really useful to him anyway, the practical alternative is the standard MONITOR/RECEIVER made by Sony, Panasonic, JVC, Hitachi, E lectro home , RCA, GBC, etc.
These units are basically high-quality TV receivers with special inputs and modifications that permit them to accept video and sound signals through the appropriate VTR, camera, and audio connectors. Monitor/receivers can reproduce both sound and picture. The monitor/receiver has become a standard piece of equipment and is now commonly referred to as a TV MONITOR or just MONITOR.
Monitor/Receiver Comparisons
A wide choice of monitors (monitor/receivers) is now available with b&w units ranging in price from $200 to $400, and color monitors costing from $250 to $1,500. Monitors should be compared on the basis of their features and picture quality.
Be sure to compare:
Number of lines resolution—Is it "high resolution" (600-700 lines b&w, 350 lines color) or standard resolution (300-400 lines b&w, 250 color). The higher the resolution, the better the picture.
-Video and audio input/output connections
Does it have the ability to accept an 8-Pin
VTR plug and other common video and
audio connectors?
-Sound fidelity—How big is the speaker? -Color quality—How good is the color?
-Accessories—Does it have AFT (Automatic Fine Tuning), a sharpness control, or other useful features?
Probable trade-offs of features for cost may have to be made if you want to save money. For a monitor standard to compare with, use any Sony monitor.
All 2-inch, 1-inch and most sophisticated flinch and 1/2-inch master production VTR s require monitors for playback. At least 1 or 2 monitors are essential for serious video production and editing. They provide a viewing system for VTR playback and simple camera display. The monitor/ receiver also allows you to record TV programs off-the-air and record them on any VTR.
Use of Standard TV Receivers and RF Units
Standard TV receivers can be used with VTR s only if the VTR has either an optional or built-in RF MODULE or RF ADAPTOR.The R F Adaptor converts the video and audio signal from the VTR into a very [ow-power TV broadcast frequency which then can be accepted by any standard TV set. For example, a channel 2 RF Adaptor when connected to the VHF terminals of a standard TV set will "block out" the regular channel 2, and play back the videotape from the VTR on channel 2 on the TV set. Other TV channels will be unaffected.
NOTE: An RF Adaptor will only allow you to play back your tape on the TV set. The RF Adaptor will not allow you to record a TV program off-the-air from the TV set. To record off-the-air programs, you need either an external TV tuner or a monitor/receiver.
Use of RF Adaptors
Most RF units consist of a plug-in module (A) which fits in the back of the VTR (B) and a 75 ohm to 300 ohm standard cable TV type transformer that connects the RF cable to the VHF terminals on the TV set (C). R F units can be purchased for several different channels (you only need one). It's best to get one for a channel that is not being used in your local area, otherwise the local channel will burst in loudly when you turn off the VTR, creating an annoying amount of sound and a distracting picture. See Chapter 7RF OUT, Making the Right Connections.
R F Adaptors are not standardized and take all kinds of shapes and sizes. Make sure you know what particular model RF unit is designed for your VTR. Many VTR s cannot use RF units. Check the VTR before you buy it. Look for the RF plug on the back of the VTR and check for an empty or full RF adaptor compartment. If the adaptor is not included, add $80 to $120 to the price of the VTR. If the VTR has a selector switch that provides a choice between two channels—i.e., Channel 2-Channel 3—that unit has a built-in RF
Adaptor.
Connecting a VTR to a Monitor
Use the 8-Pin to 8-Pin cable to connect the VTR to the monitor. Plug one end of the 8-Pin cable into the receptacle marked TV on the VTR and the other end of the 8-Pin into the receptacle marked VTR on the TV monitor.
The 8-Pin cable carries both picture and sound both ways, from the VTR to the TV monitor and from the TV monitor to the VTR. This dual function allows VTR playback and off-the-air recording only if the monitor is a monitor/receiver.
VTR Playback on a TV Monitor
Step 1 Move the INPUT SELECTOR SWITCH on the monitor to the VTR or EXT (External) position. This switch should be located on the front, back, or side of the monitor.
Step 2 Play the tape on the VTR and adjust the monitor for the best sound and picture quality.
Off-The-Air Recording on the VTR
Step 1 Connect the 8-Pin cable to the VTR and monitor.
Step 2 Tune in the desired TV program on the monitor.
Step 3 Place a blank tape on the VTR.
Step 4 Set the VTR INPUT SELECTOR SWITCH to the TV mode.
Step 5 Push down the RECORD BUTTON on the VTR. Now turn the MONITOR INPUT SELECTOR to the VTR mode so you can monitor the picture and sound levels. The picture and sound now should be looping through the VTR and back to the monitor. This monitoring mode is called the E-TO-E MODE or E LECT RON ICS-TO -E LECT RON ICS MODE.
NOTE: Direct "E-to-E monitoring" only confirms that the signals are going through the VTR circuitry properly. It does not confirm that the VTR is recording properly on the tape. Only a tape playback will confirm that the VTR is recording correctly.
Step 6 Place the VTR in FWD (FORWARD) mode and record the program.
TV monitors come in various sizes, ranging from 9 to 25 inches, and in both color and black-and-white, TV monitors can be either portable or nonportable. Generally, a video production group will have several different size monitors, because portable units are better for transporting and for remote shooting, and large-screen units are better for group viewing.
TV Monitor Connectors:
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VTR 8-PIN—Connect an 8-Pin cable from this plug to any VTR. This plug provides full 2-way playback of picture and sound from the VTR to the monitor and allows off-the-air TV program recording of both sound and picture.
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TV OUT A video output — Connect a UHF cable from here to a VTR VIDEO IN plug if you are not using the 8-Pin plug and connector for this purpose. Use this output as an alternative way of recording off-the-air TV programs from the TV monitor.
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TV OUT — An audio output which is used with the MON OUT (video) plug for an alternative way of recording off-the-air programs from the monitor.
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MONITOR OUT — An audio output which is used for looping (continuing) the sound to another monitor or sound amplifying system.
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MONITOR OUT — A video output which is used for looping the picture on to another monitor.
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EXTERNAL IN—An audio input—Plug an audio cable from the VTR (LINE OUT) into this receptacle.
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EXTERNAL 1N—A video input—Plug the camera cable or a cable from the VTR (VIDEO OUT) into this receptacle.
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75 0 (ohm) TERMINATION—Terminates EXTernal IN or VIDEO IN plug. If a camera or VTR is plugged into EXT IN or VIDEO IN, place the switch in the ON or 75 ohm position. If EXT IN and EXT OUT are both in use the termination is not needed and, therefore, change the switch to the OFF or UNTERMINATED position.
NOTE: Monitors always must be TERMINATED correctly to avoid degraded picture quality. Termination is a way of telling the video signals where to stop. It might be likened to a bumper on the end of a railroad siding. A wrongly terminated picture is usually indicated by excessive contrast in the picture.
Generally, 4 to 6 monitors or TV sets can be connected to a single VTR before picture degradation is apparent. However, avoid long cable runs which can cause eventual picture loss if amplifiers are not used. If more than 6 TV monitors are to be connected, video and audio signals must be amplified. A DISTRIBUTION AMPLIFIER (for video monitors and monitor/receivers) or an RF AMPLIFIER (for TV receivers) should be purchased.
RF Multiple Receiver System
You also can connect multiple TV receivers or monitor/receivers together with an RE system. This is much easier than trying to run separate video and audio cables. You need a 2, 4 or 6-way RF SPLITTER and a corresponding number of 75-ohm to 300-ohm transformers and cables with type "F" RF plugs on each end. You will need one transformer for each TV receiver. The transformers cost only about $2.50 each, while the splitters are $6 to $10 each, depending on their size. They can be purchased at most TV/Radio stores. Tune all TV sets to the proper RF adaptor channel. REMEMBER: R F systems do not work quite as well as direct video connections.
DC Restoration
Always try to buy only cameras and monitors (monitor/receivers) that have DC RESTORATION circuits in them. Essentially, this is a circuit which restores the DC signal elements to the output of the camera or monitor. Without DC restoration, the picture will have uneven background shading, and whites and grays will merge together. Solid blacks and optimum contrast levels will be lost.
Color Monitors and Receivers
Conventional color monitors and TV receivers work by firing 3 separate electron guns (red, blue, and green) through a SHADOW MASK onto the phosphor coated face of the cathode ray tube (CRT). The mask is full of tiny holes and this helps to focus and control the beams so they strike only the appropriate red, green, or blue dots on the screen. The trouble with this system is registration—making sure each separate tube's signal is perfectly lined up with the other two.
The Sony Trinitron concept uses only a single gun that fires through a special APERTURE GRILL onto red, green and blue vertical stripes instead of dots on the CRT. Electron beam scattering and faulty convergence on the tube face is eliminated, and the resulting color quality has become the industry standard by which all other color TV sets and monitors are judged. Even the most expensive Conrac broadcast color monitors use the Trinitron TV tube.
The image deteriorates much faster in color than it does in b&w, especially when you are working with 1/2-inch and 3/4-inch VTR systems and low cost color cameras. For this reason, it is very important to have a good color monitor so the picture will look as good as possible on playback. Also, if the color monitor does not display dependable and accurate color, there is no way of knowing whether or not the color camera or the VTR is working properly. Therefore, at least one quality color monitor is required for even the most basic of serious color video productions.
In order to avoid the "third generation loss-ofsync blues," you should have at least one monitor in your system with the professional features of UNDERSCAN and PULSE-CROSS DISPLAY. A b&w monitor is perfectly sufficient for this purpose. Underscanning displays the entire image produced by the camera or VTR, including the edges of the picture which are normally cut off by standard monitors and TV receivers. The Pulse-Cross Display shifts the picture both horizontally and vertically to show the horizontal and vertical sync signals.
A Pulse-Cross display can reveal errors in VTR SKEW (tape tension), tracking, and time base stability. Pulse-Cross can also be used in editing to reveal out-of-sync edits, giving the user the chance to redo the edit so it does not carry on into successive generations of program material.
Costs of Color Monitors
Generally, color TV monitors cost at least twice as much as the comparable-sized standard TV receiver. Sony has the greatest variety of color monitors. The Sony Trinitron series ranges from the world's smallest 4-inch color monitor/receiver to the world's largest — a 30-inch studio quality unit. The Trinitrons are considered to be some of the best and most rugged monitors and monitors/receivers for the money. Panasonic, MGA, Sharp and JVC also make very good monitors and monitor /receivers.
Small portable color monitor/ receivers start at around $300-$400 for the JVC CX-6710US. Larger units like the Sony or Panasonic 17 or 19-inch monitors will cost about $900. There are also very sophisticated rack-mounted high-resolution monitors made by such companies as Barco or Conrac which cost from $3,000 to $5,000 for a 17 or 19-inch monitor. These monitors are usually found in broadcast TV studios and editing facilities and are indeed most amazing.
Special Purpose Monitors
Certain specialized monitors are necessary for serious TV production, because they will reveal what is really happening to your video signal.
Most standard monitor/receivers are too "forgiving" of video and sync abnormalities. Thus, when your third generation (copy of a copy) tape gets played back on someone else's video system, the picture suddenly jumps and shakes and loses color—much to your surprise. "Well, it looked fine on my monitor when I was editing it," you remark apologetically.
Panasonic makes a nice 9-inch 700-line high resolution b&w professional studio monitor (model WV-5310), with all these features and more. This unit is available in a single monitor desk-top style or in a 19-inch rack-mount version and each type includes an audio amplifier and an 8-ohm speaker.
One of the best checks for sync, skew, time base stability and tracking, is a very old tube-type Conrac monitor. I picked up an old set of double rack-mount 5-inch Conracs for about $80 many years ago and found them absolutely invaluable for editing and checking the stability of VTR and tape playbacks. Those old Conracs have such a slow or LONG AFC (Automatic Frequency Control) TIME CONSTANT that they lose their hold on the picture with anything less than perfect sync and tape tension (skew).
Skew errors during VTR playback produce a timing error or time displacement of the horizontal sync pulses at the point where the picture playback from the VTR switches between the 2 video heads. This error causes the top of the image on the monitor to hook to the right or to the left depending on whether the video track has become too long or too short. Older monitors and TV receivers with a long time constant in their horizontal scanning circuits will cause the video to be displaced by as much as 100 lines, thus producing noticeable distortion at the top of the picture. See Chapter 10—SKEW ADJUSTMENTS, Connecting the VTR.
Extremely short or fast AFC time constants are used in all Japanese TV monitors and newer American TV sets which simply hide all those "black nastys" that lurk within the sync pulses and the control tracks on your master tapes.
There are several ways you can check out what's really happening on your tapes. You can purchase an OSCILLOSCOPE or WAVEFORM monitor (electronic test equipment), and/or find an old rebuilt Conrac video monitor ($120), or buy a good pulse-cross display monitor, or purchase an add-on pulse-cross conversion adaptor that will enable your monitor to function also as a pulse-cross display monitor.
Comprehensive Video Supply Corporation has a fabulous gadget that allows you to cope with the unseen horrors of skew and sync pulse error. It's cal led "The Tweaker," and it serves as a waveform monitor and pulse-cross display when used with a b&w or color monitor and also functions as a video distribution amplifier.
The waveform sampler permits measurement of the composite video signal, and the pulse-cross display repositions the monitor picture so you can see the sync and blanking pulses and VTR head switching point. This information then allows you to precisely adjust your VTR skew and tracking controls for optimum playback. For $395, "The Tweaker" would be a sound investment for any video production facility.
A pulse-cross monitor or a super-slow time constant monitor is good cheap insurance for editing, and it allows you to constantly check VTR skew and tracking adjustments. This prevents much trouble and disappointment later.
Most high quality video projectors will receive standard TV programs off-the-air and also allow playback of a VTR or video camera through the projector. The projector's image usually doesn't look as sharp as that on a standard TV set because of the projector's great picture magnification. This apparent loss in picture quality is created by the 525-line limitation of the American standard TV picture.
The larger the image, the greater the separations between the scanning lines, causing the picture to appear to be diluted or even out of focus, if you are too close to the screen. For this reason, a 9-inch or 12-inch TV image will always look better than a 25-inch picture at the same distance. The quality loss is particularly noticeable with a 72-inch VTR playback.
The same situation occurs in film when you try to blow up a Kodak instamatic picture to 11 x 14 inches or to poster size. Not much picture sharpness remains. A good quality video projector,
though, will really overwhelm you and will provide a dazzling picture if you can secure high quality videotapes or if you have excellent Cable TV or antenna reception.
Types of Projectors
There are many kinds of video projection systems in use. Basically, they are divided into two main groups, the 2 or 3-tube projector type and the reflected TV set type. The quality of these two types differs substantially, and the newer systems are much better than the older models in terms of brightness, clarity, sharpness and color quality.
There are also several styles of projectors, and generally, each manufacturer offers a choice. Advent Corp., who was the first to introduce a good projection system under $5,000, has a single piece projector — the VB-125, and an excellent quality two piece system — the VB-225. Two piece systems are more mobile but need initial alignment and often require design of the room around the projector.
The advent "Videobeam" system uses 3 projector tubes, one for each color — red, green and blue. The colors are then combined on the screen to form a realistic image. Most TV projection systems offer screen sizes from 4 to 7 feet as measured diagonally. The big screen projectors also offer hi-fidelity speaker systems and powerful amplifiers for improved sound.
Sony has 2 consumer models called the "Videoscope" Series. They are the 50-inch Model KP-5020 and the 72-inch KP-7220. These systems use three unique 5.5-inch monocolor liquid self-cooling picture tubes with aspherical plastic lenses for good resolution over the entire surface of the screen. Sony also has a ceiling mount projection system, the VPK-720, which is designed for conference rooms, has 3 screen sizes of 4, 6, and 8 feet, and uses larger and brighter projection tubes. As with the Advent systems, a variety of video devices can be directly connected to the projector. Sony, Panasonic and Quasar offer single piece systems, and Panasonic and Quasar also have rear projection systems. Another very good two piece system is the Kloss "Novabeam" which is one of the less expensive ($2,500) quality systems currently available. The MGA large screen TV is another excellent quality system.
Buying a video projection system requires the consideration of many factors such as image brightness, clarity, color quality, simplicity of operation, screen durability, rear screen vs. front screen projection, video and audio inputs and outputs, and of course price. Generally speaking, only the 2 or 3-tube type projection systems ($2,500-$3,500) are adequate for professional or large group use.
No doubt in the near future we will find the LED (light emitting diode) MATRIX video wall screens becoming popular and available. Then we will have achieved truly high quality large-screen video. These screens will emit video images with the brightness of a calculator or digital wrist watch instead of merely reflecting images as current video projectors do.
There are many low-cost TV projection systems now on the market, ranging in price from less than $1,000 for home TV kits to $300,000 for huge concert-hall systems. Before you buy, be sure personally to view in operation any projection system you might consider. If you can afford good equipment, video projectors can transform TV and video into a whole new dimension. It's like having a drive-in movie theatre in your own home. However, because the TV image is so enlarged, you will really notice the quality differences between videotape and film, and also the effect of good and bad lighting.
Experts predict that in several years, 1Q% of all new color TV systems being sold to consumers will be large-screen systems. Hopefully, the technical and creative content of the medium and the availability of low-cost videotape programming and hardware will improve sufficiently to make large-screen TV a worthwhile investment.
