Sony's original requirement for a new home video tape shell was that it
should be about the same size as a paperback book, thus making it easy
to be carried in a pocket, and the running time of the tape should be sufficient
to hold a complete feature film.
At a size of 155 mm x 95 mm x 25 mm and a linear tape speed
of 20 mm/s (NTSC) giving a maximum recording length of 120 minutes (L-500),
the Betamax tape fulfils these requirements perfectly. The VHS tape being
190 mm x 105 mm x 25 mm has a higher linear tape speed making
it larger and awkward to carry and wasteful of shelf space.
Like all contemporary home video formats (Video 1500, Video 2000 and
VHS), Betamax tape is a ferric oxide tape of width half an inch.
The actual magnetic tape is interchangeable between the formats allowing
manufacturers to produce tape which could then be spooled into shells of
the desired format.
From the original L-500 Sony later produced tapes in a range of seven lengths.
These were as follows:
From this table it can be seen that the naming of the tape refers to the
length in feet (the length of the tape). This means that the PAL L-750
is the same tape as an NTSC L-750 with the only difference being the running
time. Contrast this with the situation between an PAL E180 and a NTSC T180
which have the same running time but contain different lengths of tapes.
In Europe, Sony's range of tapes was marketed under the name Dynamicron.
At any one time each tape was available in two type, Standard and Ultrahigh
grade (UHG). Over the years, Sony tapes went through several revisions
beginning with mostly grey packaging.
Beyond ferric tapes
BASF were the first on the market with a non-ferric tape which was intended
for use on the standard Betamax machine. This was a chrome dioxide formulation
which was claimed to give improved picture reproduction.
As Sony developed and improved the Betamax format by giving us Super
Betamax (Super-BETA) and Extended Definition Betamax (ED-BETA) a higher
performance tape formulation was also required. The traditional ferric tape
formulation was superseded by a metal oxide formulations.
The first of these tapes was the Pro-X tape which worked with the Super Beta Pro mode found on the SL-HF750 and SL-HF950.
After this came tapes for the ED-BETA format. Sadly there
are very few PAL ED-BETA machines available, in the NTSC market lots of
models were produced and some are still available. Although Pro-X tapes
were intended for use in Super Betamax format, they were often found by
many as a high grade tape for the standard beta. One particularly good
use was for PCM audio recordings.
PAL ED-BETA machines are now only to be found in the middle eastern
markets in countries such as Saudi Arabia and Israel.
Other than Sony, a number of other manufactures produced tapes for the
Betamax format. Not all of these manufacturers sold their tapes in the
high street and were bundled with new VCRs. Brands such as Polaroid and
Maxell were not available in all six tape length opting to sell only the
popular L-500 (2 hour) and L-750 (3 hour) variants.
Betamax tapes were available in the UK in the following brands BASF,
Kodak, Maxell, Memorex, NEC, Polaroid, Sanyo, Scotch, TDK and Toshiba.
One manufacturer Scotch promised a lifetime guarantee on all of its
tapes. Do you remember the advert with the skeleton showing the SL-C7
however reportedly, people attempting to get them to honour this promise
today, will be told that the lifetime guarantee has expired as the format
is no longer supported which is evidently not the case!
Now that new Betamax tapes are difficult to obtain, many users are turning
to Betacam tapes. Betacam is a professional broadcast format which uses
cassettes that are suitable for Betamax recorders. Although the price of
new Betacam tapes is prohibitive, there is a plentiful supply of once used
A nice feature about Betacam tapes are that most come with a reusable
erase tab which can engaged or disengaged as required. Most Betacam tapes
come in a nice plastic case similar to a Betamax library wallet making
them easy to label and look good on a shelf! Some also came with a nice
hook allowing them to be hung on a rod, a feature which was found useful
in the Broadcast world.
Note: only Oxide Betacam tapes are suitable for use with the
Betamax format. Betacam SP tapes are a metal formulation tape and are not
compatible with the Betamax format. They can cause excessive head wear
and should be avoided at all costs.
Due to highly increased running speed of a Betacam tape (about 6.5 times
faster), a 20 minute Betacam tape works out as the equivalent of an L-500
and a 30 minute Betacam tape works out as the equivalent of an L-750. Betacam
tapes of length greater than 30 minutes come in a much larger shell which
will obviously not fit in a Betamax VCR. The small Betamax sized shells
are used in the portable Betacam machines used in outside broadcasts with
the larger shells being used in the studio. Compare this with VHS and VHS-C
tapes. The other two lengths of Betacam tapes which can be used in Betamax
machines are the 5 and 10 minute varieties.
A number cleaning tapes were produced, this came in two varieties, wet
and dry. These are used for cleaning the video heads and tape path. The
wet variety is less harmful to the VCR.
Note: all cleaning tapes should be used with extreme caution
as they all work on the principle of applying a abrasive material on the
video heads which at best causes head wear and at worst can damage the
delicate video head tips. If you really need to use one of these cleaning
tapes, they should be used sparingly and only in short bursts. If no improvement
in picture quality is achieved after a couple of tape passes then further
use of the cleaning head will be a waste of time and can only lead to head
wear or damage. In which case you should either attempt to clean the video
heads by opening the machine up and using a proper head cleaning swab and
solution or the machine should be referred to a qualified service engineer.
Sony produced several tapes for service engineers. The most useful of which
is the SONY KR5-2H Alignment tape L-125 (PAL). This contained the following
test patterns: Colour bars (for video system alignment), Monoscope (RF
switching and azimuth adjustments), RF-sweep (video head preamplifier adjustments)
and tracking (tape path adjustments).
Also available is the torque measurement tape (forward torque and back
tension measurement). This comprises of a conventional Betamax shell with
two spring tension gauges located in place of the usual take up and supply
spools. When the tape is played, the gauges give a readout of forward torque
and back tension on the take up and supply spools respectively.
These were heavily marketed by the trade who played on common myth that
because the Betamax system did not unlace the tape whilst wind / rewind,
there would be excessive head wear. It is undoubtedly the case that using
a tape rewinder will result in less head wear but history has shown that
the saving is marginal. The convenience factor of being able to go on and
view another type and not have to wait for the previous cassette to rewind
is perhaps a better reason for using one of these rewinders... an even
better solution would be to own a second (or more) Betamax machine.
In the UK, rewinders were available from high street shops such as Tandy
(Radio Shack) and Dixons.
Betamax leader tape consists of metallic material.
The tape end sensors in the Beta format operate on an inductive system,
with each sensor being a coil forming part of an oscillator tuned circuit.
When they come into the proximity of the sensor, they cause it to saturate
and the oscillator to stop.
The benefit of this arrangement is smooth end detection and increased
reliability compared with an optical arrangement which are particularly
prone to failure of the optical emitter which on early VHS models was a
tungsten lamp. When this failed, the machine becomes totally inoperable.
See also the Betamax features page.
Current Sony tapes
Sony still supply Betamax tapes although they are now hard to
find in the high street. For a list of supplies see our directory
Sony's web site gives detail of both Betamax
and Betacam tapes.
It is sometimes quite surprising to find that not everyone is aware that
video tapes like audio tapes also have a record tab. On a Betamax cassette
this it is usually removed by using a small screwdriver thus stopping
the tape from being recorded over accidentally. These can be re-covered
if necessary using some sticky tape.
Industrial models such as the SLO-1700 ignore
the record tab and will record even if the tab has been removed. As these
machines are often used for duplicator banks this makes sense as tapes with
the tabs already removed can be used.
See also Betacam tapes.