Tech Talk

by Joe McCleskey
April 1998

In general, what lux rating is sufficient for a family camcorder? And what is the lux rating for the average camcorder?

Enloe Wright
Internet

Lux is the standard measurement used in determining how much illumination is present in a scene to be videotaped. One lux is equal to the amount of light generated by one standard candle, measured one meter from the candle and spread across a one meter square surface.

Camcorder manufacturers often use low-light performance as a selling point; still, you need to be careful not to make a purchase decision based solely on the lux numbers they provide. Often, the manufacturers will claim something as ridiculous as 0.5 lux sensitivity, which means you can shoot by half the light of a single candle placed one meter from the subject. This is utter nonsense; all the manufacturers have done in this case is determined at what level a picture appears on a monitorany picture, no matter how murky or grainy. To get an acceptable picture that you'd want to show to your family or friends, most camcorders require around 1000 lux (equal to an overcast day or an office lit by fluorescent lamps).

To help you determine how well a camcorder operates in low light conditions, the Electronic Industries Association (EIA) has developed a set of guidelines for manufacturers to use when assigning lux ratings to their camcorders. Unfortunately, most manufacturers still won't list these specifications in the literature that comes with the camera. Most camcorders test somewhere in the 8-20 lux range using the EIA guidelines, but even at this level, the picture looks very grainy and murky. The best way to know if a camcorder will operate in the conditions you require is to simply ask the salesperson to let you try it out, then use it in a variety of situations and light levels right there in the store.

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While shooting video with an S-VHS camera, I have the video and audio outputs of my camera cabled directly to the input of my S-VHS VCR. The audio is using a typical RCA connection, and the video is connected via the Y/C cable. My question: is the tape in my S-VHS VCR recording a first-generation or a second-generation signal?

Edwin Targonski
Internet

In the scenario you describe, the video and audio recorded onto your S-VHS VCR would still be considered first generation. However, it would be a first-generation copy that's ever so slightly more noisy and degraded than the tape in your camcorder. This is due to the simple fact that analog video and audio signals always pick up electronic noise whenever they move through cables or circuitryperiod. A second-generation copy would imply the added degradation that comes from actually recording the signals onto tape, then re-recording them onto another tape.

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Exactly when did the VHS-C format come out on the market? How many lines of resolution does it have compared to VHS's roughly 240 lines? And what exactly do the letters VHS-C stand for?

Richard Guevara
Escondido, California

VHS-C (Video Home System-Compact) was among the first consumer videotape formats. It began life as JVC's VideoMovie format, which in 1983 used half-inch tape to record home video in a not-so-compact camcorder. By 1985, JVC had begun calling the format VHS-C, to emphasize its interchangeability with home VHS VCRs.

Performance-wise, VHS-C is identical to VHS (about 240 horizontal lines optimally, as you say), but camcorders will vary in the resolution they will produce, based on the quality of the camera and the recording mechanism present in the unit.

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You always say that the key to good audio is to get the microphone close to your source, but what if you can't? I do a lot of wildlife video here in Alaska (mostly bears) so you can see why I have to maintain some distance.

Thomas Payer
Internet

In general, you want to get the microphone close whenever you can, but when you can't, what you need is a device called a parabolic reflector. Often used on the sidelines of sporting events or in wildlife situations just like you've described, a parabolic reflector is essentially just a piece of round parabola-shaped plastic wrapped around a microphone, with the microphone's pickup placed just in front of the opening of the parabola (see illustration this page). Pointing the large open end of the parabolic reflector at the source you're attempting to record will pick up sounds coming from precisely the direction you want, eliminating other sounds and effectively isolating the source you want to record.

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