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Differences Between 8mm Tapes
I recently used up the only three Digital8 tapes that I possess. In the act of obtaining some more at the local Wal-mart store, I came across two types of 8mm tapes: Standard Grade (SG) and HMP. The former is recommended for Video8 analog recording and the latter is recommended for Hi8 analog recording and Digital8 digital recording. My Sony DCR-TRV350 Digital8 Handycam can use both tapes for digital recording, which causes my dilemma of picking the right tapes to purchase. The SG tapes costs about half as much as the HMP tapes. Question is whether I will see a difference in the results.
In order to eliminate my dilemma, I picked up a SG tape and a HMP tape in my hands to have a side-by-side comparison. I was sure technical specifications on the packagings will sway me one way or another . . . until I realized that the technical specifications are no where to be found on either tapes. Other than Sony's recommendation to use each tape for their primary purpose, I had no other means of deeming the quality of each types of tape.
In the past, the analog music tape packagings had signal-to-noise ratio charts for the consumer to evaluate the quality of each type of tape. In the analog world, signal-to-noise ratio is important, since higher signal and and lower noise produces the most optimal reproduction of the original recording.
In digital world, the reproduction of the recording is not dependent on the signal-to-noise ratio of the tape. As long as the tape's signal-to-noise ratio surpasses the minimum threshold requirement, the signal can be reproduced; 0 is a 0 and 1 is a 1. Therefore, signal-to-noise ratio specification stamped on the packaging would not help the consumers. Nevertheless, another form of quantifiable technical specification is needed to inform the consumer the benefit of using the different types of tapes.
This thought, of course, begs the question: "If the digital format eliminates the signal-to-noise factor in the picture quality equation, then the picture quality of the videos recorded on Video8 and Digital8 tapes are exactly the same, right?"
In order to answer this question, technical specifications for the tapes must be gathered. Digging deeply at the Sony's various web-sites produced no result; clicking on the "Specification" tab produces a blank specification chart. The only solution left is to read and make sense of the marketing claims. (The marketing quotes in this article are all obtained, verbatim, from Sony's media web-site.)
Standard Metal MP
The Standard Metal MP tapes are the most basic tapes used in Video8 recording.
"Standard Metal MP tape maintains high RF-output even after 200 repeated playbacks."
The quote above provides the baseline to all Sony's 8mm tapes. We know from it that the standard metal particle tapes can be played back 200 times without losing signal strength.
The Metal HG tapes are originally introduced for Hi8 recording. Later, these tapes are used for digital recording when Digital8 equipment were introduced.
"Metal HG features picture quality 12% better than standard metal particle tape. Ideal for use with Sony Digital8 Camcorders, Hi8 tapes deliver superlative performance."
This quote quantifies that the Metal HG tape is 12% better in picture quality than the Standard Metal MP tape. From earlier reasoning, the digital format eliminates this possibility, therefore the first statement in this quote can only apply to analog signals recorded on these two tapes. The second statement claims that the Metal HG tapes, when used in Digital8 camcorders, produces better results than the Standard Metal MP tapes (assumed). But we know that it can't be better in picture quality, due to the digital signal and that it did not provide quantification (evidence) to its claim. So we will simply ignore this sentence.
Hi8 Metal Evaporative
"Hi8 Metal Evaporative tape delivers the highest retentivity of any Sony consumer tape."
Here is one quote that will be very useful at comparing between its tapes. Because it uses the word, "highest", we can say this quantifies this tape to be the best at performing certain functionality compared to the other tapes. The only problem is that I do not understand the meaning of "retentivity". Perhaps my vocabulary is lacking. But to get to the bottom of things, I elicited www.dictionary.com to help.
The first definition was useless; sounds redundant and circular. But the second physics definition was technical enlightening. Based on this definition, we can say that Sony claims the "Hi8 Metal Evaporative tape delivers the highest [capability to remain magnetized after recording] of any Sony consumer tape." In layman's term, this tape is the best for archival purpose, compared to other Sony consumer tapes! Although this quote did not provide the actual numerical data to backup its statement, we found no means to contradict it. Therefore, we will accept it at face value.
"DVCPRO also uses a different tape formulation (Metal Particle) instead of Metal Evaporative type used in DV/DVCAM tapes. Metal Particle tape generally has a much greater resistance to wear than Metal Evaporative tape, and is most common in broadcast formats." - How do the different digital tape formats (DV, DVCAM, DVCPRO, D-9, Digital Betacam) compare? (See "Related Links" section.)
Based on this claim and the earlier Sony's claim of its Metal Evaporative tapes, we can deduce that Metal Particle tapes are better for repeated editing and viewing while Metal Evaporative tapes are better for archival purposes.
Interesting to note . . . all of the MiniDV tapes that are available to the public consumers at the local electronic and department stores are Metal Evaporative (ME) tapes. I have not seen any Metal Particle (MP) MiniDV tapes yet.
Professional Metal Particle (HMPX)
"HMPX features high-power magnetic particles packed at high density with special particle alignment in a new dropout-resistant binder. Durable construction and strict quality control results in a products which will stand up to the riggers of editing while maintaining low dropouts, even after multiple passes in still and shuttle modes"
I found this quote from Sony's professional media site. I could not deduce any quantify technical data from these marketing claims. It only seems to enforce the third-party claim in the previous section.
Professional Metal Evaporated (HMEX)
"HMEX features Sony's metal evaporation technology for outstanding Hi8 picture clarity. HMEX features a controlled surface roughness which reduces modulation noise and when combined with the advantages of metal evaporated technology, HMEX is ideal for high resolution camcorders."
The only thing I can deduce from this quote is that the HMEX tape will produce better picture quality in Hi8 analog mode. And it tells us that it does so by "[reducing] modulation noise".
There is one physical difference between a Video8 and a Hi8/Digital8 tape that can be seen by the naked eye. In the pictures below, the Video8 tape has a covered middle hole, while the Hi8/Digital8 tape has a punctured middle hole.
Will a Video8 tape perform just as well as a Hi8 tape in analog recording?
Based on the deduction process in this article, the answer is no for picture quality. The Metal HG Hi8 tapes produces 12% better picture quality (at least it does on a Hi8 recorder).
Will a Video8 tape perform just as well as a Digital8 tape in digital recording?
Based on the deduction process in this article, the answer is yes for picture quality.
However, there may be other factors that we are not aware of during this process. For one, it may be possible that the Video8 data density just slightly meets the threshold requirement and after prolonged used, it could deteriorate and produce more error and even frame dropouts. Of course, this is just speculation on my part without any real technical data. I thought of this possibility after reading this post.
So far, there is no real technical data to back up the fact that Hi8 are better for digital recording than Video8 tapes. And there are strong logic to back the possibility that Video8 tapes are just as good as Hi8 tapes for digital recording.
Unless we come across real technical data, the only way to know is try recording digitally on Video8 tapes practically through daily use. I will post the result of the long term test here in the future.
In the mean time, if you have any technical data concerning these tapes, please let us know.
Copyright © 2004 by Chieh Cheng. All Rights Reserved.