You gotta have tape. Especially since all consumer video formats depend on little cassettes full of the stuff. While we may dream of a video future with video memory chips or micro disk drives inside our camcorders, in the coming years we’re still going to need tape.
So how do you choose the right tape, the best tape? Some folks shop by price: there’s a Sony sale at the supermarket, or Maxell madness at the mall. They stock up on whatever brand is cheapest.
Are you brand conscious, brand loyal? Do you buy Panasonic tape because your VCR is a Panasonic? Do you search out the Memorex brand because you were impressed with their “Is it live or Memorex?” audio tape commercials? Do you buy Fuji tape because you love their colorful blimp?
Okay, we’ve asked a lot of questions, now let’s get down to some answers. Here is “All About Tape” in five easy lessons.
Videotape is a ribbon of plastic coated with one or more layers of magnetic material. A magnetic material is one that is attracted to a magnet, or can be made into a magnet (“magnetized”).
With all videotape but Hi8 ME (more on this format later), manufacturers apply a layer of magnetic material, called the coating, to the polyester base in a liquid form. Then they dry and polish the tape. Next, they slit the tape into the desired width, anywhere from 3/4-inch down to 8mm.
After slitting, they load the raw tape onto large spools (“pancakes”) which in turn feed the little plastic shells we call cassettes.
Your Video Recorder
When recording, the heads in your VCR or camcorder magnetize the tape’s magnetic layer, leaving a microscopic pattern corresponding to the audio and/or video signal you wish to preserve. On playback, your machine can detect and amplify these magnetic patterns and recreate the original audio and video signals.
You probably know that iron and steel are magnetic. Two other metals, nickel and cobalt, also qualify. Videotape coatings consist of one or more of these materials ground into a fine powder, mixed with a binder, or glue, and deposited onto the flexible tape backing.
Tapes come in an assortment of lengths for different running times. The most popular VHS and 8mm tape length is 120 minutes. Longer lengths, such as 160s and 180s, are gaining in popularity, while shorter sizes (30 and 60 minute) are nearly impossible to find except through mail order and pro dealers. These shorter tapes usually cost more than the 120s–a rare instance where you’ll pay more for less. You’ll find that the same pay-more-for-less principle also applies to VHS-C and S-VHS-C tapes. Though most of these tapes run just 20 or 30 minutes, they often cost more than full-length tapes.
According to the tape makers, no special handling is necessary for T-160 and T-180 tapes. These tapes tend to have a thinner backing to load more tape into the shell, though manufacturers often use a stronger material to resist tape stretch. Some VCRs or camcorders allow you to throw a switch when using these lengths, recalibrating the transport for rewind and fast-forward.
We want our video to look good on the screen. We want it to stay looking good through several generations of dubbing (copying) or editing. We also want it to look good a few years from now. All these concerns require a tape with good electrical and mechanical specifications.
The first spec that comes to mind is the signal-to-noise ratio, or S/N. Measured in decibels (dB), this is the ratio of pure signal to the background “noise” added by the tape.
Noise, for our purposes, is any unwanted signal mixed in with the signal you do want. Video noise shows itself as random, moving specks of color floating through your picture. Snow, that white stuff you see when watching a TV channel that is not broadcasting, is essentially pure video noise. The roaring sound accompanying it is a good example of audio noise. As we said, usually unwanted.
You also want a good frequency response so that your tape will reproduce the highest frequencies of the audio and video signals you feed it. If it is lacking in high frequency response, the picture will appear blurred, lacking resolution and fine detail.
On the audio side, poor high frequency response makes voices sound muffled, and music sound like it’s coming out of an AM radio.
Related to the S/N ratio is output or sensitivity. Higher sensitivity in a tape results in a stronger video signal for the same amount of inherent tape noise. The result is a better signal to noise ratio. Higher output tapes with better sensitivity are the ones to buy.
Some tapes will list a signal-to-noise ratio in their literature, one for audio, and several for video–they give the chroma (color signal) specs separately from the luminance (brightness, or black & white signal).
Here is where the manufacturer’s specs don’t tell the whole story. Their S/N ratios refer to one tape’s performance when compared to a reference tape. But what tape is the reference? It might be the manufacturer’s “standard grade,” one that’s never sold in stores. Or it might be something else. The specs could be deceptive, or (more likely) just plain meaningless.
Obviously, the quality of the camera and recorder will affect the overall video S/N–and here we discover that most tapes are capable of performance that exceeds that of your hardware. In other words, as far as picture quality goes, your camcorder design makes more of a difference than the quality of the tape you use.
This is not to say that tape quality doesn’t count. Good tape can make a difference in head wear, avoiding costly VCR repairs and cleaning. And it will hold up longer in storage, aging gracefully over the decades instead of rotting away in its box.
One reason for using good tape: it’s consistent and therefore predictable. It can help you keep tabs on the condition of your equipment. If you start getting more video noise, and you know your tape is good, then you know you may have a problem with your equipment.
When we test magnetic tape, we look for certain physical and electromagnetic properties. It’s the scientists, the chemists and the engineers who really know about these things, but they’ve blessed us here with some of their knowledge.
Let’s look at a few of the electrical characteristics of magnetic tape. First, coercivity. This is the intensity of a magnetic field (measured in Oesteds, abbreviated Oe) needed to completely record the magnetic pattern on the tape.
Typical VHS coercivity readings range from about 680 to over 750 Oe. Super VHS tapes have higher readings (800-1000 Oe). With S-VHS, a stronger magnetic field is necessary to record the higher frequencies for that format’s improved horizontal resolution.
Pure metal tapes (8mm, Hi8) have two to three times higher coercivity than oxide tapes. Regular 8mm camcorders use what is called metal particle (MP) tape. This formula has a coercivity of about 1500 to 1600 Oe. The slower tape speed and smaller tape size require a denser signal compared to VHS, and the higher Oe characteristic is part of how they achieve this.
Manufacturers developed metal evaporated (ME) tapes for improved picture quality in the Hi8 format. While MP suspends the magnetic particles in the binder, ME tapes have the metal evaporated directly onto the polyester base, making the binder unnecessary. Coercivity of ME tapes is lower than MP–about 1000 to 1100 Oe, which complements the electrical characteristics of Hi8 camcorders.
Some users have complained about problems with ME tape, claiming that it doesn’t hold up with repeated passes and editing. To address their concerns, Fuji recently came up with a hybrid of sorts–their Hi8 ME Position tape. They use an extra-thin (.3 micron) metal particle layer on top of a thicker (2.6 micron) layer. Fuji claims that the overall result is a MP tape more durable than metal evaporated, but with the higher ME specifications. You use it just like ME tape.
The next tech spec to consider is retentivity, or remanance (measured in Gauss, abbreviated G). Retentivity measures how well the tape holds the magnetic charge after it’s passed the record heads. This spec affects a tape’s noise performance, as well as its ability to preserve a recording for an extended period of time.
Again, the small formats (8mm, Hi8) are drastically different than 1/2-inch tapes. Where VHS tapes retain a flux density in the range of 1200-1800 G, 8mm tapes start at 2400 G and range up to 3700 G for the MP types, and up to 4000 G with ME tapes.
Let’s Get Physical
The physical characteristics of the tapes you use are as important as their electrical specs. You want your tape to be the correct size, of uniform thickness, free of dropouts, and strong enough to withstand the rigors of still-frame, repeat plays and edit shuttling.
Videotape’s magnetic coating is made from microscopic-sized particles. By microscopic, we mean particles measured in microns (one micron equals 1/1000 of a millimeter). For VHS videotape, the most common particle used is a black iron oxide known as magnetite. There are other oxides of iron, and other chemicals you can mix with the oxide to improve performance. For example, when you add cobalt to the mix, the magnetic coating acquires a longer name: cobalt gamma ferric oxide.
On VHS tapes, this magnetic layer is commonly two to four microns thick, while the tape itself averages 18 microns in thickness. Both the magnetic layer and the base of 8mm tapes measure about half the thickness of the VHS variety.
In order to record so much information on such small tape, the 8mm system utilizes various alloys of pure metal instead of oxide in the mix.
With good quality tape, you can expect precision slitting, and the tape width will vary only slightly, about 2 microns from one edge to the other. With VHS tape, this means a variation of only .016 percent.
Dropouts and Shedding
No one likes dropouts–those pesky random white lines that sometimes flash through our videos. If you freeze-frame the tape, you can see the dropouts–they look like holes in the picture.
Each dropout is a tiny instant of zero energy, with no signal coming off the tape. The problem can arise during the recording process, or it can pop up on playback.
During the record function, if your rotating video head fails to completely penetrate the tape surface, it will record little or no signal. It only takes a fraction of a microsecond of missing signal for a dropout to become visible.
Dust and smoke particles, however small, can get between the tape and the heads, causing dropouts. A dirty environment, whether at the tape factory, at home or in the field, is not good for magnetic tape.
Dropouts most often occur when a tape sheds its own coating. This can happen if the binder is poor, or if you don’t store the tape properly (see sidebar on tape care). In the early days of video, poor tapes were plentiful, and shedding was common. It is seldom a concern today.
Many years ago, the 3M company added an extra layer to their audio and videotapes. They applied a graphite compound to the base side of the tape, away from the magnetic coating. Their reason for doing this was to lower static electrical charges (which build up during fast wind/rewind) and improve the durability of the tape–especially important for editing. Their studio-quality audio tapes and broadcast videotapes were soon known by their dull black backside appearance.
Today, some tapes are back-coated and some are not. While the advantages of backcoating were (and still are) real, improvements in tape manufacturing have made it a matter of choice for tape makers, and not so much a big deal to you, the user.
One manufacturer told us the big advantage for back-coated tapes is they will resist damage from defective VCRs. In most cases, if your VCR is eating tape, it’s time to get it looked at, rather than buy armor-clad tape, which probably won’t work anyway.
Types and Choices
We examined a typical mass-retailer’s video shelf recently. Behold their offerings: VHS T-120s labeled as Polaroid, Maxell Silver GX, Maxell Gold HGX, TDK EHG, TDK HiFi, Scotch, RCA, Sony V and Sony V Premium.
When we looked for extended length tapes, we found T-160s from Polaroid, and only Scotch brand in the VHS-C package. For Betamax users, the choice was Sony regular and Sony HG, while 8mm sizes came in TDK, Sony and Scotch brands.
Our shopping exposed only the tip of the iceberg. What we couldn’t find at first were BASF, Goldstar, JVC, Panasonic, Fuji, Philips, Kodak, and Memorex. A trip to another retailer, one stereo shop and a grocery store solved the problem–without driving more than a few miles, we were able to find most all of the known major brands.
What about minor brands? We found plenty of those, too. Some are distinctly house brands, packaged for the larger retailers. Others are just low-profile tapes, usually a few cents cheaper than the name brands. Just what are in these packages?
They don’t say on the box, but they might be top quality, name-brand tape. Or they might be the product of an obscure, unlicensed factory–unworthy of your purchase. You can’t tell from the country of origin–major tape makers have factories in the USA, Japan, Korea and other places.
Making the Grades
Just as gasoline comes in regular and premium, so does videotape. And just like gasoline, premium tape commands a higher price.
But unlike gas, tapes are not marked with their video octane ratings. If you search for it, you may get some numbers from the tape company’s sales literature. Or you may draw a blank.
You can compare tapes and prices only among the same manufacturer’s tapes. One company’s “Super High Grade” may be equal to another’s “Standard Grade.” And some makers only have one grade, and they can label it any way they desire.
But can you tell the difference? The answer is, it depends. Depends on the quality of your equipment, depends on the quality of the recorded signal, depends on the number of generations you plan to edit or dub to.
Take an example: JVC’s PRO HF tape offers less noise and more output than their SX tape. It could make a visible difference on a $1000 VCR playing to a brand new big screen home theater setup, but you’re not likely to notice on a $199 deck viewed on a 13-inch TV.
Since quality is subjective and the source of never-ending arguments, we suggest you evaluate your equipment and make some tests of your own. If you can see the difference, then you can decide when to use the better tapes and if the regular grade is good enough.
According to the tape makers, the higher grades use smaller magnetic particles, which gives them higher coercivity, greater rententivity and better high frequency response. Their S/N ratio is higher, their output may be higher–everything about them tends to be better. Some are backcoated for longer wear and protection against damage.
In the VHS format, Fuji makes HQ (their standard tape), Super HG (better), and A/V Master (best). According to the company, the two premium tapes have higher output, and lower audio/video noise. All three have the same durability for extended still-frames, which is important for editing.
In their S-VHS line, they have two grades. Their standard grade is called Fuji S-VHS, but was formerly known as “Super VHS Pro.” They also have what they call their truly professional grade tape, H471S, which is a backcoated tape and comes in a hard shell library case.
Maxell’s videocassettes are known as GX-Silver (good), HGX- Gold (better), XL-HiFi (best). Like Fuji, Maxell promises a little more output and a little less noise for their higher-grade tapes. They offer one S-VHS tape–they call it XR-S Black.
In the 8mm camp, there are similar choices–Sony Metal MP and Metal HG; TDK’s HS and E-HG, as well as two from Fuji Metal and two from Maxell. And that’s only the beginning; a myriad of selections exist for all manufacturers and formats.
Why so many choices? Why not make only the best? The answer is simple economics (yours as much as theirs). When the difference doesn’t show, who wants to pay extra for it?
Home taping would not be as popular as it is if not for today’s two-dollar, two-hour blank VHS cassettes. But as you can see, there’s more to life than cheap tape. And plenty to choose from.
Tips For Longer Videotape Life
- Treat them gently. Dropping cassettes, even onto a soft carpet, can damage the tape inside. It will show up on playback as poor tracking, wrinkles or dropouts.
- Store them comfortably. Not too hot, not too cool. A range between 50 and 90 degrees Fahrenheit is best. Avoid leaving tapes in the window or in a closed automobile on hot sunny days. And aim for a relative humidity of 30 to 60 percent–avoid damp basements and other moisture-prone places. A general rule: if you’re comfortable, your tapes are comfortable.
- Keep away from magnetic fields. Suspected sources of unwanted erasure include magnets, speakers, stage lighting controls, large motors, power cords, arc welding equipment, motorized conveyer belts, etc. Aluminum foil and other non-magnetic materials cannot shield against magnetic fields.
- Keep ’em clean. Avoid dust, dirt, smoke, soot, crumbs and buttered popcorn. Don’t open the cassette or touch the tape unless it’s jammed or broken in your machine. Your own finger prints on the tape can cause dropouts, and wrinkled tape will exhibit nasty lines upon playback. These will not go away.
- Don’t leave the tape in your machine. Extended pause, still-frame and even a camcorder’s standby or stop mode can strain the tape and stretch it or wear it out.
- Exercise your tapes. About once each year, do this for every tape you own: either play or fast-forward to the end, then rewind to the beginning. This will prevent edge damage and lower the possibility of tape layers sticking to one another. Using a tape rewinder can save your VCR from this boring task.
- Let them stand up. Store tapes upright with the full hub lower than the empty one. And don’t move them around more than necessary. Don’t stack tapes flat–the weight of the reels can damage the edges of the tape.
- Rig for the long haul. To archive your videos, seal them in plastic, and if humidity is high, put a bag of calcium chloride desiccant inside to absorb moisture.
Recording’s History and Folklore
You may have heard the story: early magnetic recording (strictly audio) emerged in the 1940’s. The first practical machines were “wire recorders” because the recording medium was a spool of thin steel wire. When engineers glued magnetic (brown iron oxide) particles to long strips of paper, “tape” recording was born.
Soon thereafter, someone decided to bond the iron oxide particles onto a thin plastic backing. The 3M company, makers of Scotch brand cellophane tape, takes credit for those early magnetic tape batches. In simple terms, they stuck brown oxide onto their Scotch tape. And it worked quite well.
The videotape recorder (VTR) was born in 1956, when the Ampex Corporation delivered the first VTR to a television network.
We owe our camcorder/VCR heritage to those refrigerator- sized, $100,000 monsters that consumed two-inch-wide tape at a cost of $100 per hour. Today’s VCRs operate on much the same principles, only the hardware is smaller, quieter, and cheaper.