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Sunday, April 1, 2007

HD Digital Video


The world of high-definition video offers new opportunities for nature photographers


The HD standard is set for all cameras because they must be able to play back video on all HD sets and monitors. Cameras produce resolutions of 1920 x 1080 pixels or 1280 x 720 pixels, commonly shown as 1080i or 720p (i and p refer to interlaced and progressive scans, which we’ll return to shortly). This is hugely better than the standard digital video of 720 x 480.

These cameras aren’t cheap by any means, but considering what you get, the price is remarkable. A compact, three-chip, pro-level camera will run about $4,000 to $6,000. A compact, one-chip camera designed for consumer use can be had for $1,000 to $2,000. To get anything close even a few years ago would have required an investment of $20,000 or more.

The difference between one-and three-chip cameras (the "chips" refer to the number of sensors) is in the ability of the camera to capture tonal range, color and light in darker conditions. In bright light, you’d be hard-pressed to see the difference between these cameras, though the three-chip camera will typically have a slight edge in color rendition. In low light, a three-chip camera will capture scenes with less noise, better tonality and richer color.

I recently worked with a one-chip Canon HV-10 and three-chip Canon XH-A1. My friend Michael Guncheon, HelpLine columnist for PCPhoto, took a look at the HV-10 footage on a high-end studio monitor (he’s a partner in a video postproduction company) and said it looked amazing when shot in good light. That’s a testament to the capability of this class of camera. The A1 is even better and understandably is becoming a popular choice among pros who want a compact, one-piece HD camcorder.

(A side note: I can’t recommend the HV-10 for serious video shooting, however, because it has no microphone jack. Good audio is critical for video and you need a separate microphone, whether a shotgun or wireless, to achieve that. However, Canon has announced the HV-20, essentially the same camera with a different shape—and a microphone jack!)

Digital Horizons: HD Digital Video

Both cameras are 1080i camcorders, meaning they produce interlaced video (though the A1 and HV-20 have progressive options at certain speeds). You can stimulate a debate among video people by asking if interlaced or progressive is better. Video is produced by scanning a signal at very high speed across the monitor. Interlaced units do it faster by scanning alternate lines in two passes, which appear in two "fields" that combine into a frame of video (video’s default speed is 30 frames per second). To some, this makes the video look a little smoother.

Progressive units scan the whole image at once so one frame of video is complete. This is a real advantage when taking still shots from video because each frame is done as a single unit that doesn’t have to be blended. Also, progressive video can look sharper than interlaced, which is why 720p looks very similar to 1080i (1080p offers a very high quality but demands a camera with very high processing capabilities at normal speeds of 30 frames per second). Taking stills from interlaced video is trickier since action will emphasize little lines that aren’t part of the scene (they look like a comb on the edge of the action)—artifacts from the twice-scanned interlacing process.




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