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to Macie Video:The Headlines
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DEDHAM, MA -- Roger
Macie, for two decades a video service & repair pro and products
developer, and Mark Bell,
Contributing Editor of Television Broadcast magazine, repair pro and consultant,
will be updating this page with articles and results of their research
into making life easier for those in the field.
Camcorder Survival Kit
Getting the Most Out of Your Video Equipment
By Roger Macie
As we all know, preventive maintenance of video equipment is one of the keys to trouble free productions. Videographers and field crews must be able to perform regular maintenance themselves. By preventive maintenance I mean keeping the video tape recorders' heads and transport clean. Clogged heads account for more bad video than any other VTR problem. With frequent cleanings and spot checking, you can prevent the major cause of poorly recorded video.
Feedback on my maintenance tip articles has shown me that you need more than just the written word to help you with proper operation and maintenance. As a result I have committed myself to creating and producing a series of maintenance and operational training videos with whatever components are needed to help you get the most out of your video equipment.
I created the "Camcorder Survival Kit" to provide the best products needed to properly maintain your VTR and camera optics. The "Kit" includes a video taped instruction and demonstration of techniques needed to safely clean all betacam field VTR's and camera optics, along with actual through the microscope shots of deposit build-up and playbacks of bad video through the viewfinder, field and studio decks.
VTR and camera optic cleaning components as well as hard-to-find items such as a prepackaged video head cleaner, anti-fog agent for lenses, the "LensPen" cleaning brush system, and a set of high grade metric screwdrivers are part of the "Kit." Packaged in a convenient soft case with the ability to purchase individual elements of the "Kit" as spares or refills make this one of the most convenient resources to hit the television marketplace.
By Mark Bell
If you've been in the industry for more than ten years, you can appreciate how far the medium has progressed. As we have advanced ourselves, the manufacturers have advanced us with the absolute miracles of technology. But sometimes, with those miracles, there comes a learning curve.
It has been discovered that metal tape use vs. oxide product will double the life of tape heads. This good news also comes with some not-so-good news.
A compound that may be a product or by-product of the lubrication used to facilitate metal tape travel "slippage" has been thought to be the cause of a situation similar to a head clog on small format camcorders. Identified by Roger Macie, of Dedham, MA, as "baked-on" residue, this situation has caused "clog-type" characteristics that do not disappear with standard cleaning methods.
This advisory is not a cause for alarm as much as a call for facility maintenance people to learn a different regimen for maintenance of the SDH series (small head diameter) VCRs. Microscopic observation of the head followed by cautious use of a head-cleaning cassette is recommended for dealing with this situation. Be cautious, however. The tip penetration of the smaller diameter heads and expense of head replacement mandates more than casual use of an abrasive head cleaning cassette. If you don't know, leave it to a pro. Your head is a terrible thing to waste.
Macie's Find
Roger Macie, a veteran maintenance technician, recently gave notice
to Ikegami and Sony that he was seeing a consistent pattern of a compound
amassing on the heads of SDH series machines.
Macie discovered the characteristic during a microscopic examination of the heads that were performing consistent to a VCR with a clogged head, even after a rigorous cleaning.
"Clients were coming in with badly recorded tapes with one or two heads apparently clogged," Macie says. "Their original perception was a chroma breakup, of sorts, that I came to see as that, and a distortion in the RF envelope."
Conventional cleaning methods such as head cleaner and/or alcohol and a clean wipe are not effective in removing the compound.
"The only way I could effectively clean this compound off the head was to use an abrasive cleaning tape," Macie adds. "Even then, some heads do not clean off enough to totally eliminate the marks I saw under the microscope, and warrant a second or third 5-second pass with the cleaning tapes: the stuff was really on there!"
One thing that may be a bit scary about this characteristic is that there is not always an RF warning when there is a "baking" condition. There is not a large deficiency of RF, which is the keying point of RF warning signals. There is, however, distortion of RF envelope that will similarly distort your video.
Manufacturers Response
Tom Calabro, Executive VP and Director of Engineering for Ikegami,
US, is aware of Roger's discovery, and expressed confidence that proper
maintenance was the key.
This is certainly something that has to be dealt with. "It's a minor disadvantage, but can be dealt with by performing proper maintenance, just like changing belts. Those cleaning tapes that you used to keep on the shelf? You'll need to use them now."
Dan Smith, Senior Technical Services Representative from Sony's Alabama Media Plant, is also familiar with the challenge of the "baked-on" compound.
"The drum spins faster in the (SDH) product. And the contour of the surface of the tape is different. These factors alone may lead to a situation that warrants a more frequent cleaning of the heads," he says. "We are always looking to change or modify our products to make them better, and perhaps a cleaning every 40 to 50 hours with one of our micro-abrasive cleaning cassettes is a characteristic of a newer more superior technology.
Reinforcing Smith's opinion, a bulletin from Sony Electronics Recording Media Productions Group says the following: "In order to remove this build up, Sony recommends a complete cleaning every 20 hours of tape time. Sony also recommends that a head-cleaning cassette be used every second cleaning (40-50 hours) FOR ONLY FIVE SECONDS." Sony has also issued a service bulletin for this "build-up" characteristic.
Roger has had different experiences with different build ups, and has had to run an abrasive tape for as long as 60 seconds to remove excess mass on some heads. This long time period is not recommended without simultaneous microscopic monitoring. Leave it to a pro with the tools Macie states: "Checking the CTDM (compressed time division multiplex) signal while playing back the last 15 or 20 seconds of a recorded tape is (an accurate status indicator}. Any distortion, or breakup, in this signal would warrant cause for concern, and perhaps some cleaning on the spot. It is essential that the last 15 seconds be played back, and not too much less, as you can also control track discrepancies, another symptom of the condition. These are not always apparent with a quicker playback of 5 seconds for instance.
What's the saying? "There is no such thing as a free lunch." Here we have this great gear that'll do it all with such nice quality, but it's not free. We are saving money on one hand, but having to spend some of the savings on maintenance. This "baking" characteristic, while not apparent on CDH VCRs, is as much a part of the state-of-the-art SDH VCRs as FM audio. If you are getting the highest quality out of the product and saving the head wear via metal recording media, you'll also have to change your habits and perform frequent cleaning.
A thought worth some merit is to use an SDH camcorder with a separate CDH series VCR for location production shoots when the characteristics of such work allow for the larger package. This lessens the chance of the "keeper" being affected by the baking phenomenon.
Other principles of consideration have pointed toward tape storage. Sony Corporations Recording Media Products Group published a comprehensive advisory in January of 1991. MPG Technical Report Volume 6 can educate the reader on "Archival Stability." The report is very well written and details and not-so technical points.
The MPG Tech report, obviously, would not be able to address newer series of tapes like the BCT-D, BCT-Ma, and UVWT-Ma tapes which are superior to those of previous years. Sony and other manufacturers will continue to improve their technology, and it is certain, as long as we are in a technology that depends on heads and tapes, we will encounter the effects inherent to the techniques.
John Matarazzo, National Technical Services Manager for Sony's Recording Media Group agrees. "Improvements in lubricants and binding systems produce conditions that will improve the vulnerability of tape."
Being more specific, Matarazzo says, "The new BCT-Ma series has improved cross-linking (mechanical composition) and has systems that contribute to a reduction in surface debris."
It's an age of new technologies that require different methods of performance and maintenance than the technologies of the past. Field color shifts, multi-frame distortions and repetitive dropouts do not necessarily indicate situations that warrant extensive repair. The cause might be from manageable characteristics that warrant attention by different methods of, and more frequent, cleanings.
Joseph Tibensky, Director of Marketing for the Recording Media Products Group, adds, "During the normal evolution of any product, we try to make as many improvements as possible. Sony BCT-Ma series between Betacam SP cassettes, which have now been on the market for two full years, feature improved runnability, cleanliness and durability beyond that of the previous BCT-M series. Since the introduction of this formulation, and that of the similar Broadcast Master formulation for D-2 cassettes and HMPX Hi8 formulation two years ago, the Sony Professional Media Division has been enjoying the highest level of professional video cassette product reliability in our history."
Avoiding Head Clogs
By Roger Macie
The purpose of this series of articles is to help you, the broadcast and professional videographer, maintain problem free recordings at minimal cost. Camcorders and other video tape recorders are electromechanical devices that need regular scheduled maintenance. Your true cost includes not only maintenance, but costs caused by a lack of preventive maintenance. Downtime, emergency rentals, re-shoots, and possible client loss, can cost more than a comprehensive preventive maintenance program.
I want to focus on video head clogs which inevitably happen to all VTRs. Video tape heads develop a buildup of material that will eventually decrease the head to tape contact and result in partial or total loss of RF signal recorded on tape. Playback of recordings with low RF signals shows up as a higher number of dropouts, video break up, or color problems. Predicting exactly when a head will clog is nearly impossible. There are too many variables in the recording process that contribute to the cause of head clogs; humidity, temperature, tape formulation, and VTR condition, to name a few. Requent head cleaning is still the best insurance and least expensive preventive maintenance that you the videographer can do.
There are two types of deposits, each requiring a unique cleaning technique to remove. The first and most common deposit is a buildup of debris on the head that usually comes from the tape or the environment. This buildup is easily removed with the appropriate cleaning fluid and a lint free cleaning cloth. The second type of buildup is more prevalent with Betacam SP camcorders than with other types of field and studio VTRs. These internal VTR decks have smaller video drums with heads that spin faster and have greater tape wrap than conventional VTRs. This design difference results in higher head tip temperatures that literally "bakes" material on to the head tips. Eventually, buildup of this type of deposit will result in a poor recording. This phenomenon shows up more frequently on camcorders that use metal tape. Oxide tape use, because of its higher abrasiveness, results in less of this "baked-on" type buildup. The problem with this type of deposit is that it cannot be removed with standard wet cleaning techniques; only a head cleaning tape will remove these deposits.
To Minimize head clogging, try the following:
a) Begin a regimen of proper deck and head cleaning. Blow dust from the tape transport with a pressurized aerosol duster. Use a BCT-5CLN head cleaning tape on Betacam SP camcorders to remove baked-on deposit buildup. Wet clean the tape path of VTR and video head drum with 99% isopropyl alcohol and a lint free cleaning cloth. As a starting point for cleaning intervals, wet clean every 20 hours of tape time. Use a cleaning tape every second wet cleaning, or each 40 to 50 hours of tape time. FOLLOW CLEANING TAPE INSTRUCTIONS! Never play the cleaning tape for more than five seconds at a time during each cleaning interval. Cleaning tapes are very abrasive and will wear down the heads prematurely if used incorrectly. In this case, more is not necessarily better.
b) Find a qualified maintenance engineer who uses a head tip inspection microscope and have your deck professionally inspected and cleaned every hundred tape-run hours. This inspection will assess how effective your cleaning routine is. If there is no sign of " baked-on" deposits cut back on using the cleaning tape by increasing the intervals between head cleanings. While your camcorder or VTR is in for professional inspection and cleaning, have the video head tips measured for wear, the tape tensions checked and pinch roller inspected and replaced if worn.
c) Even though field recorders have an RF loss warning detector to alert you when a head is badly clogged, partial head clogs may not be detected. To catch these while shooting in the field, check playback in the viewfinder regularly. Besides the normal luminance (B/W) playback, check the color video signal by depressing the CTDM button. Luminance and chroma signals in the Beta format are recorded simultanious on two separate tracks. Marginal or no RF signal on the tape will playback in the viewfinder as noisy video that breaks up in the normal or CTDM mode. Look for a higher than normal drop out count as an early sign of a partial head clog. With camcorders you must stop recording to check the playback. On decks equipped with confidence playback capability you can check the tape playback while the recording is in progress by using the RET (return) button located on the camera lens.
d) Use "VTR save" mode as preferred mode of operation. Needless head spinning while in contact with tape not only adds to debris buildup but decreases video head life.
e) If you have a separate field deck, spot check your tapes throughout the shooting day. This procedure will not only show head clogs but also other problems that could occur with either the camera or VTR.
f) If you suspect problems with the tape stock, put a sample recorded tape aside and inform your maintenance engineer and tape manufacturer representative. Tape companies welcome and need your feedback if you experience problems with their stock. A suspected bad batch of tape can hurt the reputation of a normally reliable product.
The cost of a proper cleaning and maintenance program is an investment that pays great dividends.
From PROfiles Magazine, ProSource's Newsletter, as submitted by Roger. (Ask us about ProSource)
One of the major attractions at the 1995 NAB convention was the formal introduction of the Ikegami/Avid DNG (Digital News Gathering) Camera System with Digital Disk Recording. Three distinct models were displayed.
Each of the two Camera/Recorder systems (DNS-11 FIT CCD and DNS-101 IT CCD) incorporate a disk recorder where video is recorded directly to a removable "Fieldpak". The digital random access format of the Fieldpak permits immediate on-line non-linear editing. The Fieldpak houses two 1.2 gigabyte hard disks, offering up to twenty minutes of total recorded video.
Also presented was the CamCutter Recorder. This dockable recorder, along with the one-piece systems, allow direct access to Avid's Field Editing System. In the News Gathering industry, time is a most precious commodity. Ikegami's proprietary DNG system translates into considerable time savings! A total DNG system can empower you with video acquisition, recording, playback and editing to transmission.
Disk based recording opens up a new world of unique production techniques and system features. A prime example is RetroLoop. This feature allows you to constantly record in a pre-defined loop of time from 15 to 60 seconds. When the unexpected happens, you will have it. Just hit the record trigger. Video stored in the RetroLoop is added seamlessly to the front of a new clip ("Take") with no wasted disc time or lost shots.
Most of the major broadcasters we spoke with during NAB agreed that tape will be around for many years. even those who will be first to take advantage of a field disk recorder will still have to use a combination of disk and tape systems. One fact is clear when field editing is not a consideration, media costs continue to favor tape. ENG, on the other hand, is really what this technology was created for. Time will tell.
Matchmaker, Matchmaker
By Mark Bell
Our field is like many where technology and technique leapfrog as time goes by. At this particular time, it's the two- camera shoot that is becoming more popular, and two cameras at the same location need to match if the production is going to look as good as possible. While today's CCD technology offers easy set-up, different camera models from even the same manufacturer can pose a problem when it comes to getting pictures to match on a simple two-camera shoot.
Some companies have, or have had, a camera set-up/shading standard. Some techs just do it by experience, which may mean that nobody ever told them to work in conformance with a particular standard. In today's market there are many shops, and the likelihood of one standard being observed in any two separate shops has proven to be small.
Some companies provide crews with a video technician, others assemble crews without a tech and rely on various independent shops for camera set-ups and maintenance. Needless to say, an on-site tech is the way to go, but not always provided for in this tight-budget world.
In this world, non-uniformity of set-up standards translates into post production time and expense, as organizations are spending time in post production color correcting before actual editing is started. There's no reason that this extra step is needed if it can be eliminated up front.
A Call to Arms
From the very diversified experience of Macie Video Services in Dedham, MA, Roger Macie expresses the following: "There is a call to fill the need of both sides of the camera market [camera person and client] to create a de facto standard that can be set up away from location and be equal, or at least very comparable, on sight, without on-site adjustment."
In other words, we need to have a uniform national standard. One person from one area of the country should be able to meet with one from another and have a match much closer than is routinely observed.
"It's a huge problem," continues Macie. "From my clients, I hear frequently of situations that demonstrate the need for a standard. It amazes me how many cameras seem not to be set up to any standard with consistency when I get them into the shop."
According to Macie's experience, gammas and flare compensation are two adjustments critical in matching. Flares, for instance, are frequently not set correctly. One quick telltale sign of this can be seen while a camera is pointed at a "pure" white chart with an "absolute" black reference in the center. If the pedestal moves consistently more than a few units while opening and closing the iris through its range, flares should be adjusted.
While researching this article, it was observed that a clear filter, with coating imperfections due to wear, caused a remarkable change in flare performance, showing the need to use top-quality optical equipment. Any changes in lens components after set-up may affect flares and therefore, matchability on site.
Gammas are simple enough to see on any standard chart, but what is tough to see is consistency in gamma level setting from one camera to the next.
Another interesting point of note is that the traditional 7.5 unit pedestal is not well-suited for today's cameras, as 7.5 tends to clip some of the signal. Pedestals of 8.5 and higher are becoming typical, but so far there is no real standard for this "new" setting.
Practical Solutions
Macie is experimenting with DSC's rear illuminated charts, also called "Optical Signal Generators" by the manufacturer, to study the implementation of a standard. The rear-illuminated charts provide a consistent level of light, without reflection. Macie has had a lot of success with this system and is looking to expand its use in seeking a standard.
Another reason to use the "Ambi-illuminator," according to Macie, is that it's the only chart that can provide a stable reference for color matching matrix adjustments. The term "optical signal generator" is accurate in terms of how it allows for a reproduction of a standard bar's test signal on waveform, vectorscope and video monitors through a camera's optics.
"The charts allow me to be very specific when making color adjustments." Macie adds.
A second method of creating a uniform set-up environment is used by Steve Finer of Finer Associates in Watertown, MA. He had similar feelings about light source consistency and uses Sony's "light box" to obtain what he feels are his "Finer" results.
"Starting with a calibrated uniform light source is probably the most important step," Finer offers. "You can take any of the cameras I have worked on, put them side by side and they will match. The newer cameras don't drift like older models. If not [field-adjusted] they should stay pretty much as set up in the shop."
There are opinions that rear-illuminated charts or light boxes may not properly reproduce test patterns. For this reason, some technicians shy away from any rear-illuminated concept.
S.H. Traditional Method
Brad Reed, a veteran operations and maintenance professional associated with Broadcast Technical Group of Hopkington, MA, is a traditional chart person. He prefers to use the standard Porta-Pattern charts for set-up.
"I've seen a lot of projected image devices," Reed says, "and don't feel comfortable with the transfer characteristics versus the standard charts. If kept clean, taken care of properly, and renewed if faded, the chart is a proven method.
"Many times a camera set up in the shop does not look good in the field, and needs adjustment, right then and there. Charts are easy to carry along and fairly inexpensive compared to projection devices."
But this leaves us with three different devices to perform the same task. Each technician has a solid opinion and makes the adjustments he or she believe are in the best interest of the camera, the client or the job.
There is an acknowledged need for uniformity. We've evolved to a point where a new standard is needed for field gear, as crews come from all over the place and their various shading values are "all over the place" as well. Without a video engineer on a crew, a show may be condemned to cost more in post.
Uniformity Needed
While the concept of a new uniform standard sounds "perfect world"-applicable, it may not sit well with everybody, just like the present standards do not.
Frank Governelli, Director of Bureau Operations for CBS, is very aware of the situation with mismatched camers. He confirms his awareness of the situation and offers some perspective which may speak for many.
"Some of our freelance people come into our shop so we can set up their camers to our standards. However, many shows still have built-in set-up time for color correction before post so we can get the tapes where we want them to be. In terms of a national standard though, we have to ask ouselves, 'Do we want to look like everybody else?'"
By Roger Macie
There has been a great shift from staff camera operators with company owned gear to owner-operator videographers. Networks which had control of "their look" with staff technicians, are now living with "the look" of independents. This, coupled with the increase of magazine shows being shot with multiple cameras and the general need for matched cameras, is causing a headache for independent videographers.
Producers usually call crews with similar model cameras, in the hope of achieving a matched look. When these cameras are put side by side, why is it that they often look so different? Today's cameras are so stable and have enough adjustments and range to easily match each other. The problem is that these cameras are often set up by different technicians using different charts, lighting, techniques and standards. In addition to that, manufacturers have standards for set up that often differ between models.
There are three things that videographers can do to ensure that producers are happy with their look. The first is to learn how to set up cameras to match while out in the field, or to hire a video technician for each shoot. Test charts, waveform and color monitors, along with time for setup, will be needed. With today's budgets and time restraints, this would be difficult.
The second way is to have the cameras set up and matched prior to the shoot by a qualified technician. Off-site camera setups, which are the least expensive method, are usually impossible because of short notice and scheduling problems. There is also a lack of available, local technicians.
The third, and best overall method, requires that your camera be set up to a "uniform standard". Cameras set up with identical pedestal, gamma, flare, matrix, detail and a few other parameters will closely match. For years, I have been setting up all sorts of cameras. I have found that even cameras of different manufacture, closely match the set up with the same parameters. There are many other qualified, seasoned camera technicians, who similarly set up cameras to look great, and at the same time, closely match each other's. The problem is that there is no uniform standard that has been adopted by the industry. This has forced each individual technician to adopt his own standard.
Gamma setting, for example, involved much controversy. Gamma is the setting of the gray, or mid-levels of the video signal, which is used to match the corresponding mid levels of the picture monitors or television sets. A low gamma setting makes pictures look darker and have more contrast, colors are richer. A higher gamma brightens the picture and tends to wash it out. You are probably familiar with gray scale chip charts that have a crossover on a waveform monitor. This crossover corresponds to the gamma setting of a camera. This particular crossover point varies with camera technicians. Manufacturers have recommended values for this setting by sometimes admitting that this is user preference.
Master black pedestal setting also varies between technicians. Some like it set to 7.5 IRE which is called Set Up. Others prefer 10 IRE which keeps blacks from clipping. Another important alignment is flare compensation, which is through the lens black level adjustment. When adjusted properly, true blacks in the picture remain the same as capped black, even when iris, or picture is varied. If set improperly, black levels will rise or fall when iris is opened and overall picture level will increase. If it did rise, think of what would happen to the video if talent, for example, was shot with a lot of blue sky in the background. The predominant color blue would have its black level rise higher than the red and blue channels resulting in an unbalance in black level. Changing the background to another color would cause the color of dark regions to shift again.
The encoding of the color difference signals is performed by the camera's matrix circuits. Each camera has a factory preset setting along with a customer adjustable matrix that can be used to match colorimetry with other cameras.
There are gray scale charts in use that have been available since the development of color cameras. It has always been easy to match cameras to look the same when shooting these charts. The problem, especially with cameras of different manufacture and models, is that each cameras colorimetry differs slightly. CCD blocks, lenses and different circuitry vary among cameras. These differences can usually be compensated by what is called the "matrix" adjustments. The matrix can be switched off, which is a factory preset, or turned on and set to another setting which could be the uniform standard.
A high-quality, standard color reference chart will be needed in order to accurately set up a camera matrix. There is a chart available that was developed in collaboration with the Canadian Broadcasting Corporation and manufactured by DSC Laboratories of Ontario, Canada. This is not a typical test chart, but a precision Optical Signal Generator (OSG).
With this chart and an agreed upon standard setting of gamma and matrix settings, a true, uniform look can be achieved. Factory service centers, networks and individual service technicians have begun to acquire these OSGs, the only true color reference tool available.
This "uniform standard" should satisfy most end users of video./ Having a camera set up at the highest, most acceptable standard, will result in better looking video than the average setup today. Even cameras made by different manufacturers set to the same standard will closely match.
Once a camera is set up to a uniform standard, each videographer will still have the option of changing their camera's look. Adjustments using filters, balancing through gels to get "the warm look", or even learning the basics of some alignments themselves and resetting to the uniform standard before the next multi-camera shoot will allow the videographer to change their camera's look.
I am working with some key networks, retail companies, factory engineers, and the DSC Company (Optical Signal Generator maker) in attempting to develop a uniform standard, using an OSG, that broadcasters and end users will be satisfied with. Hopefully, by the next newsletter, this uniform standard will be available to you, as a camera owner, to adopt. When your camera or camcorder goes in for service, just ask that your camera be set up to this standard.
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The Ultimate Camera Standard
By Roger Macie
In the last issue of Profiles, I promised an update on my quest for a Uniform Standard for setting up broadcast field cameras. Well, after nearly a thousand camera setups, I have achieved a Uniform Standard that has been field tested by hundreds of network and high-end videographers throughout the country. My goal was to develop a setup that would eliminate the hassles of multi-camera matching required by network news and magazine shows and provide the best overall picture quality.
With the use of the DSC Labs "Optical Signal Generator" (OSG), it is now possible to set up individual cameras to a single set of parameters and have them match. This chart, designed to SMPTE (Society of Motion Picture and Television Engineers) specifications, allows for alignments that result in near-perfect color reproduction. To complete the Standard, use of DSC's Combi2 chart allows for repeatable picture detail alignments.
With the help of these tools, and after proper setup of basic camera parameters, I documented the factory preset colorimetry by marking vectorscope overlays for every broadcast field camera that came through the shop. What I found was that all cameras had less than true color saturation, especially green and cyan. To add to the difficulty, some cameras, with limited range could not obtain full colorimetry. In spite of these constraints, I was able to achieve a vectorscope overlay that allowed near true color reproduction with all colors except green and cyan , which I set at a point between factory preset and SMPTE specifications.
The "Macie Uniform Standard" has been field tested on several hundred cameras for about a year. Resultant feedback has been totally positive from crews using this operational standard. Not only do they like the look, but show producers have begun to request crews that use this Standard. Network management has also become interested in this new concept because of years of frustration getting just their own cameras to match, never mind hundreds of freelance crews. Prior to this OSG and Uniform Standard, it was virtually impossible to match cameras independently.
Videographers, networks, TV stations, rental and production facilities, can all benefit from a proven multi-camera matching standard that not only make colors more vibrant and true, but provides for more consistent, pleasing setting of detail level. This uniform standard is also the best starting place for creating a special "LOOK" with lighting, lens filtration or with the newer digital cameras that use either scene files or setup cards.
A small investment in proper camera setup pays large dividends, improving the quality of your life and those you shoot for.
Video Head Evaluations
At Macie Video Service, we are fortunate to have some of the best clients in the Television Industry. Our clients shoot, literally, all over the world, and send their valued video gear to us in Dedham, MA to maintain optimum performance. When any videotape machine is sent in, its our policy to check head tip penetration among other items of wear. When penetration is measured, it is measured in microns. One micron is equal to a millionth of a meter.
In terms of camcorders, new heads typically measure around 18 microns. Those same heads are considered worn at 9 microns. When your camcorder or other tape machine is brought in and reconditioned, repaired or simply "gone over," we issue a statement of wear, and tell you what our measurements are. Typically, this data is in the explanation box on your invoice/service record. Camcorder heads judged to be at 12 microns, or other format VCR heads at 20 microns, are considered by us to be in fair condition. Keep in mind that you must look at the LOWEST figure to evaluate heads on an upper drum. The saying: "A chain is as strong as its weakest link" applies. Camcorder heads at 11 microns or less, for instance, are judged to be in poor condition.
What "poor condition" means is that actual head-to-tape contact may be less than what is needed for optimum recording. There may be more dropouts, or colors may flash in some areas when viewing a playback from a recording with a worn head. While a recording may look good on one playback deck, it may have severe problems on another. This, too, may be a possible sign of questionable recording.
We understand the cost of new heads, share the frustration of the wear issue, and understand the expense of losing valuable video, worse, a client. Sometimes increasing tape tension may help alleviate poor head-to-tape contact characteristics, and we may increase tension on machines with worn heads in the hope of increasing the useability of the head. However, it's important to note that a 2/3 worn head may only give you and your client 1/3 the recording integrity of a new one.
We offer the best service and knowledge our experience can give you, but you are the best judge of the level of performance you want from your gear.
It is up to you to evaluate our report in consideration of your judgement and the somewhat predictable capabilities of your equipment. Please read and make sure you understand the report you have been given by Macie Video Service.
We are always glad to explain the information, give you our recommendations, and will endeavor to keep your equipment operating at its best.
Sony Investigates Betacam Camcorder Headwear
Problems
TV Broadcast Alerts Sony To Increased Industry
Concerns
By Mark Bell (contributing editor) and Michael Silbergleid (editor-Television Broadcast magazine)
Sony's Betacam format, with more than 300,000 VTRs and camcorders, is the workhorse of the broadcast industry. But a trend has surfaced that, if not resolved, may adversely impact the format's reputation. For the past few months, Television Broadcast has been investigating premature headwear complaints-extremely low hours before failure- reported by Betacam camcorder users, who reported that the problem has become an expensive burden for broadcast stations, networks, and freelancers.
The symptom manifests itself as an intermittent and undetectable (during recording) error in the visual picture, referred to by broadcasters as an upper-third chroma problem (or what Sony calls a "chroma flash").
According to Television Broadcast Engineering Consultants at Macie Video Service, Dedham, MA, the problem appears to coincide with Sony's mid-1992 introduction of a redesigned Betacam camcorder upper head drum assembly, commonly referred to as "heads."
According to Macie, the recording problem is most likely associated with the new upper head drum assembly design. The specific cause of the problem is now being increasingly investigated by Sony, based on reports given to them by Television Broadcast and other sources.
A Change For The Better?
Sony's redesign of the camcorder upper drum assembly replaced a 3mm head tip with a 1.9mm head tip. The change was to provide a 2db increase in the signal-to-noise (an important increase for multi-generational users), while keeping the same amount of head-to-tape contact on the head (according to Sony, the entire 3mm head did not have tape contact).The first design of the head drums with this change were found to have problems with chroma head-to-tape contact, and were modified to the present model available-one that has a "dual port" drum design. The problem appears as chroma dropouts and tearing in the upper-third section of recorded video, and is undetectable by any conventional RF alarm system during recording.
The problem does not affect all users of the new smaller head design, but has been seen nationwide by videographers, news crews, and repair shops.
In a meeting held September 27, Television Broadcast and Sony discussed the problem to try to determine its exact cause. From data exchanged at the meeting, it appears as if there are still problems with both chroma head-to-tape contact and wear. The history of camcorder headwear presented by Macie indicated that problems requiring head drum changes are occurring with as little as 141 head hours, with a majority of problems and premature wear occuring under 500 hours-Sony's head-hour warranty period.
The pre-change 1992 heads typically lasted 800-1200 hours. At the present time, Sony has accommodated customers' problems on a case-by-case basis following investigation, although the exact cause of the problem is still a matter of differing opinions.
At the meeting, internal memos acquired by Television Broadcast from one network source were shared with Sony. The memos stated that the network found the problem to be undetectable until playback of field tapes, and intermittent enough to require spot checks. Included in the network memo was a call to "roll back-up", stand-alone decks on important interviews." In addition was the statement that a crew whose gear exhibited the problem would not be sent out again until the camcorder was inspected by Macie. Reportedly, the network has accepted camcorders whose heads have been replaced by Sony as well. Interviews with other sources revealed the problems were being experienced in television stations and production houses nationwide.
'Worn' Heads or 'Bad' Heads?
Sony distributed a report during the Television Broadcast meeting regarding heads that were replaced by Macie and turned in to Sony as warranty/investigation material. The report stated that all of the heads Macie replaced were not worn out, and were affected by a layer of "plastic filming," a phenomenon that Macie supplied information about to Ikegami, Sony, and Television Broadcast in February 1994. (Sony published a brochure on VTR claaning that included this topic in March 1994.
Also in the report was Sony's assertion regarding one particular set of head tips with a protrusion measurement of 17 microns and 8 microns, Y (luminance) and C (chrominance) head, respectively, which were also on the report as not worn. Heads when new, by Sony's information, have a tip protrusion measurement of approximately 25 microns.
Macie claimed the "filming" was probably due to procedures in the examination process, and has always been suspect as a cause for any problem before diagnosis. Macie also claimed that if head tips are close to, or below, 9 microns in tip protrusion, they will not provide network-quality consistent performance. The importance of tip protrusion measurement in headwear was one of the main areas of disagreement. Sony measures head life by RF performance and head gap depth-not only by head tip protrusion. Macie, and others in the industry, say that gap depth is not applicable in camcorders, as that is not a true measurement of head reliability.
The reason why this head was serviceable was qualified by laws of material physics by Sony engineers at the meeting. The fact that the original problem, recording of intermittent chroma, was solved by replacing the heads, with no other repair, was acknowledged for further study by Sony.
Sony did not acknowledge that the heads alone were the cause of the problem, as many factors incuding tape tension, correct tape path, and alignment can contribute to this type of recording error. Sony contends that replacing the heads can mask another problem within the camcorder, while appearing to solve the problem.
Historically, Macie evaluates all other camcorder parameters before heads are changed.
Although not "worn," it appears to most technicians and users that the heads replaced were "bad" in some way, as this solved the problem.
Sony indicates that original new heads with proper alignment in the camcorder, shipped out of the factory, are not facing short head life. When the upper head drum assembly is replaced, implementation of the tape path alignment and tape tension alignment is a mandatory procedure.
According to Sony, the head condition can be judged by tracking a waveform (RF performance). Before judging the end of head life, it is necessary to check the head condition after using a cleaning tape. The regular use of a cleaning tape is very important, or issues such as "plastic filming" can mislead one to the conclusion that the heads need to be replaced.
One unfortunate industry practice is that preventative maintenance procedures such as the use of a head cleaning cassette every 50 hours for five seconds (as recommended in Sony's Technical Bulletin 95-182) and re-equalization of the record current for optimal performance at 300-400 hours rarely takes place. This, no doubt, adds to the question of determining the exact cause of the problems. (To aid in maintenance, Sony has introduced the CLQ-30K, a non-CFC/non-alcohol formula Cleaning Kit.)
Additionally, Sony has a concern about those using isopropyl alcohol to clean their heads. Common pharmacy isopropyl is actually less than 80 percent alcohol, which can leave residue. If isopropyl is used, Sony recommends 99 percent isopropyl-as sold by electronics stores.
A Gradual But Increasing Trend
Although the new head drum design was first seen in mid-1992, the chroma/head problem did not appear in the industry overnight. The trend was first noticed in the Northeast, but other factors may have played a role since the intoduction of the new smaller head tips. Freon, typically used to clean heads, became less and less available between 1992 and now due to environmental concerns.
One additional concern for Sony, which is looking for more data on this problem, is the lack of heads available to test. One reason is Sony's warranty of 500 hours or 90 days. This warranty, when averaged out, means a crew would have to shoot 5-1/2 hours every day for the 90 day period. Repair facilities have told us that although the head drum may have low hours (below warranty specs), they are older than 90 days and can't be turned in to Sony for warranty adjustment.
While Sony continues to investigate this problem, they urge camcorder users with lower than expected head life to contact their Sony representatives. Sony believes that, most importantly, the design change of the head tip width has no relation to head life. Rather, correct alignment after drum replacement and periodic cleaning of the camcorder tape path are the main steps to prevent the symptom of chroma flash.
Television Broadcast will continue its own investigation into this area, while Sony studies the cause of the problem.
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