Standard 8-mm and Hi-8 have been the preferred video formats for underwater videographers for years, but smaller-sized digital camcorders may soon take the lead. What are the differences? All non-digital camcorders and VCRs (8-mm, Hi-8 and VHS) use the analog format. The video signal is a stream of fluctuating voltages that magnetically records video pictures on videotape. When you shoot or dub (copy) a videotape, the recording VCR can't perfectly duplicate the varied voltages of the video signal. Each copy of a copy loses more and more picture quality. Digital camcorders send a digital signal - a series of ones and zeros - from the image sensor to the videotape. Thus, the image is recorded accurately. If you dub digital to digital, generation loss is virtually nonexistent because the digits (ones and zeros) can be copied exactly.To visualize the differences, imagine trying to copy the moves of an orchestra conductor's hands as he conducts. No, you can't copy the fluctuating movements of his hands perfectly. However, if he said, ''One, one, zero,'' you could duplicate his commands perfectly.WHO SHOULD USE STANDARD 8-MM? If you want a low-budget personal hobby, 8-mm may suffice. Dozens of standard 8-mm camcorders are available at prices under $500. You can easily record images that will please your family and friends. However, there are limitations. First, 8-mm images will not be as sharp as Hi-8 or digital images. Plus if you make copies from 8-mm tapes, image quality declines quickly. Standard 8-mm camcorders record less than 300 lines of resolution (a measurement of image sharpness).WHO SHOULD USE HI-8? Hi-8, an enhanced and more costly version of standard 8-mm, is a popular choice for underwater videography. If you want sharper images than 8-mm without the added cost of a digital camcorder, Hi-8 is the best choice. Many of the underwater videos you've seen on TV were shot on Hi-8 camcorders. Hi-8 camcorders record up to about 400 lines of resolution. WHO SHOULD USE DIGITAL? If you want high-quality acquisition footage, digital is the way to go. Digital camcorders record about 500 lines of resolution and are expensive. Digital tapes can be copied to any other format for editing and duplication. Digital is for professionals and discerning amateurs. You won't see all the increased picture quality if you connect your digital camera to a TV set with an RCA cord for playback. This is because the RCA cord only passes about 240 lines of resolution to a TV set. Even if you used an S-video cord and TV input, you would only see about 400 lines of resolution. You would need a digital connection and a TV set that could show 500 lines of resolution. Don't let the limitations of your present VCR or TV keep you from switching to digital. Your next VCR may be digital, and your next TV set may have a digital input. THREE CHIPS OR ONE? Unless the manufacturer states otherwise, camcorders have one CCD chip. This chip must handle all the colors in the video image. Some camcorders have three chips; each chip handles one of the primary colors: red, green or blue.Any camcorder needs a minimum amount of light to record pleasing images. In bright conditions, a three-chip camcorder (either digital or analog) records images and colors more accurately than a one-chip camcorder. In dim light, however, one-chip camcorders often record better images because the single chip sees all the light passing through the lens.Choose the Housing FirstIf you don't have a camcorder, choose the housing before buying the camcorder. Ask manufacturers and distributors which camcorders fit their housings. Check the following sources for housings: Amphibico: http://amphibico.comGates U.W. Products: http://gateshousings.com Ikelite: www.ikelite.comLight and Motion Industries: www.lmindustries.comOcean Brite Systems: www.oceanbrite.comSea and Sea U/W Photography: www.seaandsea.comSea Optics, USA: www.seaoptic.comUnderSea Video Housings: www.usvh.com Live-aboard U/W Photo CoursesJim Church will conduct underwater photo courses on a variety of Aggressor vessels this year. For more information about photo and video live-aboard courses, click onto the home page below.
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