Video cassettes - how to save a bundle!
The first VHS cassettes I had the pleasure of using were made in the late '70s. Back then, if you wanted good quality you bought TDK EHG (Extra High Grade) . or Fuji HG, or JVC HG and so on. HG, back then, meant something. It meant no "snow" at picture vertical transitions. Quality.
The reason for the poor quality of non "HG" tapes was that magnetic tape had troubles dealing with VHS hi frequency signals, produced by the FM modulator chip in fast transitions. FM works that way. The snow was there because the FM demodulator compensated for the drop of signal strength in hi-frequencies, by amplifying it, and un-avoidable static noise ("snow") with it.
Cassettes became better and better, while the unchanging VHS system did not demand more than before. soon, there was no difference between 'Standard' and 'HG'. This did not mean that manufacturers would stop earning money on the "better" HG quality! oh no! so what if there is no difference at all? 'HG' was wrapped nicer, so why wouldn't it be better?
Than came S-VHS. The designers understood that if cassettes are better, you could use it to store more info! more resolution! So now the cassettes are again, pushed to their limits. Right?
Wrong! it might have been so at the beginning of SVHS. I did not test it but I personally think it was not the case even back then! I think S-VHS was not designed to use the existing tape technology to the limit! This would bring us to professional quality! why would professionals, than, pay more (much more!) for professional systems? the designers came up with Semi-pro quality. Nice market segmentation!
Now, lets get to business: VHS and S-VHS tapes
If cassettes are, again, much more advanced than the recording system, even 'standard' VHS cassettes are good enough for S-VHS! I personally think some of the manufacturers put the same tape in all cassettes, saving on operation of different production lines!
Anyway, drilling a hole at the right place, or disabling the sensor sensing the presence of the hole inside your recorder (if you know how) will enable you to use a standard VHS cassette in your SVHS recorder! See how you save a bundle?
It's obvious that for VHS recording, the most simple cassette will do. Without loosing quality. No need to buy any HG or anything, even for most important shots!
There is one thing to beware of: "Noname" cassettes sometimes contain a tape made of poor base film, making it loose magnetic material ("dropouts"), twitch, sometimes clogging the heads or even scratching them! Test those cassettes on your old VHS before putting them in your brand new S. or better - don't use them at all!
| To test the cassettes I used two methods.
One, "Professional" method was to tap into the recording amplifier and replace the recorded video signal with a special signal called a frequency sweep. The sweep was synchronized to the video head rotation, so on playback, a clear frequency sweep could be seen on the oscilloscope. By comparing the amplitude of the off-tape sweep at different frequencies from one tape to another, the relative qualities of those tapes could be measured. The tests where performed in SP and LP. The results as mentioned above, showed the same frequency characteristics among HG and "regular" tapes. very close or even similar results where obtained among SVHS and VHS cassettes. actually, in SP there was almost no noticeable difference, while very small differences where found in LP (on some cassettes). EP was not tested, as I do not have an EP recorder. The second method you could replicate by yourself: Use an SVHS recorder to record an image containing hi contrasted, sharp, vertical transitions. a camera pointed to a computer - printed pattern (zebra) or a bright window shot from a dark room with its frame dark are all useful if a pattern generator is not avilable, just make sure the focus is perfect to get sharp transitions. Record in LP or EP (if available) to push the cassette being tested to its limits. If a VHS cassette is to be tested, make sure you punch a hole in the right place (on the left side at the bottom) to make the VCR think its an SVHS tape. (see drawing) what you are looking for are the folowing results: If the VHS cassette is good enough for SVHS, than on the play back, vertical transitions will be smooth , with not too much snow on them. The best thing will be to record the same image on an SVHS tape and compare the two. |
VHS cassete: where to punch the hole:
Hi8 and 8mm tapes:
The 8mm recording system was at all possible thanks to the development of better tapes. The same quality as VHS was achieved on much less tape space, using metal evaporated tapes, instead of chrome tape as in VHS. The introduction of an even better (ME) tape enabled the production of the Hi8 format.
As in VHS, 8mm tape kinds no longer play a role in picture quality. ALL 8mm tapes, from Hi8 ME tapes (ME=Metal Evaporated, is better and more expansive than: MP=Metal Particle) trough Hi8 Hg MP tapes to 8mm and even data backup, "D8" tapes give the same results in regular 8mm recordings, both in SP and LP.
Conclusion: For regular 8mm (not Hi8), buy the cheapest cassette you can find! No HG needed!
For Hi8, the story is a bit different. to obtain the best performance, there is no other option but to use the superior, (and expansive!) ME tapes. When using an ME tape, the recorder senses a special hole at the bottom of the cassette, switching to ME mode, where the fine details of the picture are recorded stronger, so the result is a better looking image both is SP and especially in LP modes.
If you punch the ME hole on an MP tape (see drawing), fooling the recorder to believe you are using an ME tape, the result will be black strikes after sharp vertical line transitions. No MP cassette I tested gave satisfying performance in ME mode, even in SP where the tape is not pushed to its limits!
One important remark: I have tested two tapes: Fugi ME and SONY ME, although both are ME tapes, the image quality in LP was MUCH better with SONY!
If, however, you have been using Hi8 MP tapes and been satisfied with the results, and, you don't think the ME tape performance is worth the extra price - you are not alone! many, including me, think that for most jobs, MP is sufficient.
In MP mode, I found it did not matter at all what kind of tape you are using! all MP tapes I tested: 8mm, 8mmHG, Hi8 and Hi8HG yielded the same results: good SP recordings, slightly snowy transition in LP mode. WITH ONE EXEPTION: Data backup tapes are inferior even to regular 8mm tapes, and cannot be used satisfyingly with Hi8!
Conclusion: For the best Hi8 picture (if you shoot a master, later to be edited), use only ME tapes. especially for LP recordings (to tape a full length movie in PAL home recorders, where only 90 or max 110 nin tapes are available). For everyday use, regular 8mm (not hi8) MP tapes are fine. (Test one tape before buying a large quantity just to be sure).
| To test for yourself what I described
here:
Use a Hi8 recorder to record a pattern as described in the VHS testing method above. To test if an 8mm MP tape is as good as Hi8 MP, the best thing is to punch the ME hole in both of them, record in LP and see what comes out. both should give about the same amount of black striking. The above method pushes the tape to its limits by the demanding ME mode, but leaves you with two cassettes with ME holes punched you should seal in order to use the cassette. If you do not want to punch the ME holes, punch the Hi8 hole on the non Hi8 MP cassette and compare to the Hi8 MP cassette. Use LP mode and observe amounts of snow at transitions. |
8mm: where to puch the hole:
PAL - NTSC differences:
With VHS life was simple: PAL uses 50 fields a minute, NTSC uses 60. tracks are the same width, so an NTSC cassette lasts 5/6 time less than PAL. I.e: a PAL E-180 will play 150min in NTSC and an NTSC T-120 will play 144min in PAL.
8mm is different. Track width is different for PAL and NTSC. PAL speed is 2 cm/sec in SP, 1 cm/sec in LP, while NTSC uses 1.4 cm/sec in SP and 7 cm/sec in LP. If you consider that NTSC still has 60 fields/sec, than the 70% speed of NTSC tape means actually 58.3% in track width! so NTSC's SP is close to PAL LP!!! (the faster rotation of the video head 60 revs/sec instead of 50 - gives NTSC better head to tape speed, so its not that bad!) NTSC is therefore definitely more demanding on the tape than PAL, so NTSC users should double-check the cassettes they are buying. Since MP Hi8HG does not give more than regular 8mm cassettes, I would recommend NTSC users to use only ME cassettes.
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