At first it seems simple. You just got a high definition television. You notice that the image quality of your home videos seems to have declined, so you go shopping for an HD camcorder, only to be confronted with a plethora of confusing choices. To set your mind at ease, your home videos are just as good as they’ve always been, so there is no urgency to get saddled with a half understood piece of equipment today. It’s simply that your standards have changed.
1. Begin with a realistic budget. You can literally spend as much on a high definition video camera as on a house. Top end cameras produce images that are often indistinguishable from film. The good news is that low end HD cameras, such as Canon’s HV20, can be had for less than $900. If your budget is limited, then consider shooting in the HDV format. HDV was created by a working agreement between Sony, Canon, Sharp and JVC. HDV records in MPEG-2 a compression scheme developed by the Motion Picture Experts on mini-DV cassettes. MPEG-2 is the same compression scheme used on DVD. Compressing video is as essential for digital broadcasting. Without it, we simply wouldn’t have enough bandwidth to transmit all the information needed to make 30 full frame images every single second. The HDV aspect ratio is wide screen 16:9, while the format’s output is 1080i (interlaced) or 720p (progressive.) The tape run time for HDV is the same as for mini-DV. Since all HDV is limited by the top data rate of DV tape, video can be readily loaded to your computer for editing in real time through Fire Wire. However, there are differences in HDV. HDV1 from JVC records at 19 megabits per second in MPEG-2 with a resolution of 1280 x 720 pixels. HDV2 from Sony and Canon records in MPEG-2 at 25 megabits per second with a higher resolution of 1920 pixels by 1080. If you shoot JVC’s HDV1 you won’t be able to transfer through Fire Wire from a Sony HDV2 deck or camcorder. Sony’s HDV doesn’t play back on JVC either. Canon further clouds compatibility with an “F” setting to simulate24P on some of its camcorders that won’t play back on either a JVC or Sony deck. In practical terms this means that if you do plan to edit, you’ll be digitizing directly from your camcorder. When you do buy an HD camcorder, it will be a lot simpler to commit to one manufacturer for all your High Definition video needs.
2. Decide on the number of chips you need. HD camcorders use either CCD, charge-coupled device or CMOS, complementary metal-oxide-semiconductor image sensors. Each device has strengths and weaknesses. CMOS is catching up to CCD’s in image quality. Today, I’d choose a camera not on the basis of the image sensor type, but on how good a picture it produces.
As you learned in grade school, all colors can be made from three primaries. In your paint box, they were red, blue and yellow. With light they are red green and blue. By recording all of the color information separately on three separate chips you’ll keep the color information discrete through processing which will give you a cleaner image. If you record on a single chip, you’ll still get acceptable quality, but it won’t be as good. Be sure to compare the resolution capability of chips from rival cameras, generally the more lines the better.
3. Don’t get seduced unnecessarily by 24P. Film’s look is a combination of lighting, low depth of field, wide exposure latitude, moving a camera with a fixed focal length instead of zooming, and finally 24 progressive frames. Unless you are planning to use your camcorder to shoot a feature length movie that will ultimately be transferred to film and projected in a theater, there is really no need to shoot in 24 P.
4. If possible, choose an HD camcorder with assisted focus. There is less tolerance for bad focus in high definition because the image is noticeably sharper than standard def. You’d like either peaking enhancement in black and white viewfinder mode so that in focus elements are tinged with color or an option that allows a camera operator to temporarily double the center of the image for a focus check. I used this feature on a Panasonic AG-HVX200 HD camcorder to shoot a television interview last Saturday.
5. Anticipate editing. Cutting HDV footage is more problematic than cutting DV. In DV the video-compression is purely intraframe, that is within each individual image. Since every DV frame is compressed independently, the footage can be cut at any frame without affecting those next to it. Because HDV is MPEG-2, it uses both intraframe and interframe compression. In HDV, the so called “I-frame,” the only truly intact frame, is typically recorded once every half second. The rest are extrapolated across a fifteen frame Group of Pictures, or GOP. Practically speaking this means that when it comes to editing, you will be cutting on virtual frames that are extracted from the surrounding images by your editing software. Any transition while editing, even a simple cut, requires an entire decompression then recompression of every frame in the GOP. With HDV you won’t be able to layer a lot of complex effects without artifacts. It’s better to stick with tried and true film style transitions such as cuts, dissolves and the rare wipe. Sony also recommends using its better quality HDV vs. DV tape. If you’re unlucky enough to have a drop out on a recorded I-frame, you have no back up immediately fore and aft. The glitch will affect everything in your GOP.