You pick one up that seems like it would work (after all it says it is a VHS adapter), you take it home, but, to your dismay the tape doesn't fit! In a fit of rage you head back to the store you return the VHS adapter, demanding the salesman get you a VHS adapter that fits 8mm tapes.
In response to your question, the salesman rolls his eyes and tells you there is no such thing. You respond, "But my cousin in Jersey has one, he just pops in his camcorder tape in the adapter and puts it in his VCR".
THERE IS NO 8mm/VHS ADAPTER! 8mm/Hi8/miniDV tapes cannot, under any circumstances, be played in a VHS VCR. It turns out the Jersey cousin has a VHS-C camcorder which can use the VHS adapter to play a VHS-C tape in a VCR for viewing. Why is there this incompatibility with 8mm tapes? Just keep on reading.
How 8mm/Hi8 and miniDV Is Different From VHS
1. 8mm, Hi8, miniDV are different formats with different technical characteristics than VHS. These formats were never developed with the intention to be mechanically compatible with past or current VHS technology.
2. 8mm and Hi8 tapes are 8mm wide (about 1/4 inch), and miniDV tape is 6mm wide, while VHS tape is 1/2-inches wide, making it impossible for a VHS video head to read the taped information correctly, since a VHS VCR requires a 1/2-inch wide tape to play back.
3. Along with the video and audio signals that are recorded is a control track. The control track tells the VCR what speed the tape is recorded in and helps the VCR keep the tape lined up with rotating head drum on the VCR properly.
Since the control track information is different on an 8mm/Hi8/miniDV tape than on a VHS tape, a VHS VCR cannot recognize the 8mm.Hi8/miniDV control track information and, thus, would not be able to keep the tape lined up properly with VHS tape heads, nor recognize the speed at which the recording was made.
In other words, 8mm/Hi8/miniDV tapes are recorded and played at different speeds than VHS, so even if the tapes could physically fit into a standard VHS VCR, the VCR still couldn't play back the tapes at their correct speeds, since these speeds to do not match already established VHS tape recording and playback speeds.
4. 8mm and Hi8 audio is recorded differently than VHS. 8mm/Hi8 audio is recorded in AFM HiFi mode, while the audio on a miniDV tape is recorded at either a 12-bit or 16-bit digital format. This audio recording is done via the same heads as do the video recording.
The audio in the VHS format is recorded and played back by either the tape moving across a stationary head, away from the video heads, or, in the case of HiFi Stereo VHS VCRs, by a process called Depth Multiplexing, in which separate heads on the rotating VCR head drum record the audio under the video recording layer, instead of on the same layer as the video signal, as 8mm and HI8 do.
Because of the way VHS VCRs have to record and read audio, they are not equipped to read the AFM audio recorded on an 8mm or Hi8 tape, nor the digital audio recorded on a miniDV tape.
5. 8mm/Hi8/miniDV video is of higher resolution than VHS and is recorded in a wider bandwidth, that is different from VHS, so once again, a standard VHS VCR still could not read the video information correctly, even if the tape could fit into a VCR.
The VHS-C Factor
Now, lets get back to the "Jersey Cousin" who places his tape in an adapter and plays it in a VCR. He owns a VHS-C camcorder, not an 8mm camcorder. The VHS-C tapes used in this camcorder are smaller (and shorter) VHS tapes, but are still the same 1/2" width of a standard VHS tape. In order to play these tapes, there are adapters available to play them in a standard VCR.
Since VHS-C tapes are also smaller than standard size VHS tapes, many users get them confused with 8mm tapes. In other words, in the vernacular of the day, many people just refer to any small video tape as an 8mm tape, without regard to the fact that it may actually be a VHS-C or miniDV tape. In their mind, if it is smaller than a VHS tape, it must be an 8mm tape.
To verify this, take a close look at your small tape cassette. Does it have the 8mm/Hi8/miniDV logo on it, or does it have a VHS-C or S-VHS-C logo on it? You will find that if you can place it a VHS adapter, it will have to have either a VHS-C or S-VHS-C logo, which means that it is not an 8mm/Hi8/miniDV tape.
Also, another way to verify this is to go to a retailer that sells video tape, and buy an 8mm tape, a miniDV tape, and a VHS-C tape. Try to put each one into the VHS adapter you have. You will find that only the VHS-C tape will fit properly into the adapter, with the adapter closing properly, grabbing the tape so that it shows when you manually lift the front of the VHS adapter where the tape end goes into a VHS VCR.
To verify what format of tape your camcorder uses, the official logo will be on one side of the camcorder. If it is a VHS-C camcorder, you will see the VHS-C logo. If it is an 8mm/Hi8/miniDV camcorder, it will have the correct official label for those formats. Only camcorder tapes used in an official labeled VHS-C camcorder can be placed into a VHS adapter and played in a VCR.
Addressing 8mm/VHS Adapter Claims
From the above points, it can be verifiably concluded that it is both mechanically and electronically impossible for a VHS (or S-VHS) VCR to play or read the information recorded on an 8mm/Hi8, or miniDV tape. Any claims to the contrary are erroneous, and must be required to be accompanied by a physical demonstration to be considered legitimate. Anyone offering such a device for sale is either mistakingly identifying a VHS-C/VHS adapter for an 8mm/VHS adapter, or they are outright scamming the consumer.