Could you please provide me with information on how to choose the proper video tape to be used in time-lapse video cassette recorders. Most manufacturers recommend BASF, TDK, Maxell, etc. However, there are several grades of tapes made by each. Some manufacturers recommend high-grade tapes while others say the use of high-grade tapes are not a good idea. I would also appreciate it if you could elaborate a little on the consequences of using inferior tapes in time-lapse VCRs and how to best determine quality tapes from inferior tapes. Thanks and I enjoyed visiting your web site.
Sign me Taped Up in Memphis
Dear Taped Up,
To answer you question, we have to go into some detail.
The first step is to know what type of recorder that you are using and going
from there. There are currently five styles or types of recorders being used in
the Security Market today. Each has it's own purpose for being and each has it's
own needs and idiosyncrasies. I'll start with the oldest and go from there.
1. Time-lapse Recorders
Time-lapse recorders live up to their name. They work on the basis of
allowing time to lapse between taking individual images or pictures. This is
accomplished through incrementing the video tape across the tape path a
sixteenth of an inch at a time. Consequently, the video tape stays loaded in the
tape path at all times and the video heads continue to rotate at 1800 RPM (NTSC
/ 1500 RPM - PAL) at all times. To calculate the amount of time that lapses
between images at various speeds is very easy. Take the recording speed divided
by 120 and you end up with the amount of time (in seconds) that is allowed to
lapse between images. (i.e., 240 hour mode / 120 = 2 seconds lapse time between
images). Now consider that the tape path from first point of contact to end is
five inches. How long is the tape in contact with the video heads (rotating at
1800 RPM) at one-sixteenth of an inch movement each two seconds for a total
length of five inches? A long time. Now look at what a video tape is. Basically
it is nothing more than a piece of plastic with magnetic particles held in place
with an emulsion. The more particles per inch, the higher the quality of
playback and overall image. However, due to the excessive amount of time against
the video heads in the time-lapse mode, the type of emulsion and the number of
particles per inch become very important to us. The emulsion must be thin and
hard to prevent meltdown under high friction and we want fewer particles per
inch to slow down head wear. Therefore, with Time-lapse recorders, we will
always use video tapes that are basically the cheapest type we can buy. They
will be: T120 (120 minute) or two hour only; industrial grade. All of the types
that you mentioned in your question will do just fine. Just don't buy the
professional grade or best that you can. Go for cheep. This is one time that
cheep is better.
2. SVHS
SVHS machines offer higher resolution under specific conditions. However it
is important to understand that these machines also will only offer SVHS quality
using SVHS tapes. These machines will record or play back either standard or
SVHS tapes. But, if you are trying to achieve the higher resolution playback
offered by these machines, you must use T120 tapes and they must be SVHS style.
Keep in mind however, that if recorded in the SVHS mode on an SVHS tape, you
cannot play back these recordings on a standard machine. You must have another
SVHS machine. As a final note, if you are using black/white cameras, SVHS does
not offer you any advantages. SVHS is only for Color cameras and then only with
two cable feeds.
3. 24 & 72 hour / high density machines
These are the newer style machines. They offer the ability to record 24 hours
or 72 hours of images on a T160 (160 minute) tape. The true advantage of these
machines is that they offer three to five times as much recorded information per
second over the Time-lapse machine in the 24 or 72 hour mode... i.e. Time-lapse
24 hour mode / 120 = .2 seconds lapse or five (5) pictures per second. 24 hour /
high density records 17 to 21 images per second. Time-lapse 72 hour mode / 120 =
.6 seconds lapse or 1.4 images per second. 72 hour / high density records 5 to 7
images per second. Because of the unique design of these machines and the
overall speed of the tape moving through the tape path, you can use higher grade
tapes and take advantage of a better play back. The only real criteria is that
they are T160 (160 minute tapes) in order to achieve a full 24 or 72 hours of
recording time.
4. Digital Recorders
These are the newest beasts to make the scene. You may or may not have run
into one to date. When you do, you will find that you are restricted to using
DVC (Digital Video Cassettes). You will find that these are expensive (time and
demand will drop the price). Other from that, the manufacturers of these
machines will be very specific about what can and cannot be used with their
machines.
At the end of the day, I hope that this helps out the cause. If there is
anything else that I can do to help, feel free to holler at any time. I am in
your service. Thanks again for the comments on the Web ... stop by and check out
the new question of the month... I didn't realize that I hadn't posted anything
since April. Fell behind somewhere, so I may as well start with you.
