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JVC GZ-HD7: World’s First 1920x1080 MPEG-2 Camcorder, Part 1

Sep 7, 2007 12:00 PM, By Steve Mullen


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Left: 1440x1080; Right: 1920x1080
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Performance

To check encoder quality, I recorded cars speeding past the camcorder. I found no difference in MPEG-2 blocking artifacts between the 30Mbps VBR and 27Mbps CBR modes. I checked the 22Mbps VBR, SP mode the same way, and I was surprised to find no increase in artifacts.

Using Photoshop to check frame grabs, I concluded that although FullHD mode does not provide significant additional horizontal resolution, its greater luma and chroma recording bandwidth provides cleaner video with almost no aliasing. However, the quality difference is slight—so if your editing workflow requires HDV-equivalent video, you should not hesitate to use 1440CBR mode.

With the camera’s sharpness set at mid-point (default), the image has minimal edge enhancement artifacts in all recording modes. To subtly increase video clarity, I incremented sharpness by one tick. For the remainder of my testing, I used FullHD with Sharpness set at +1.

Exposure Control

Although designed by JVC’s consumer group, the GZ-HD7 has exposure controls that emulate those of “pro” video cameras. They provide the option of shooting under full manual, semi-automatic, and full automatic control. This flexibility enables a pro to choose the amount of automation required in each shooting situation.

Conversely, if you are new to shooting HD, you can shoot using the camera’s excellent Full Auto mode. As your shooting skills develop, you can learn to use the manual controls. Consumer camcorders that either lack a complete set of exposure and focus controls, or that hide these controls under menus, cannot offer you a real growth path.

  • Shutter Priority Mode: You set shutter speed by pressing the "S" button. Use the setting dial to increment or decrement shutter speed from 1/2 second to 1/4000 second.
  • Aperture Priority Mode: Similarly, you set aperture by pressing the "A" button. Use the setting dial to increment or decrement the iris: 1.8/1.9, 2.0, 2.8, 4.0, 5.6, and 8.0.
  • Full Manual Mode: You can also independently set shutter speed and aperture. However, if AGC is enabled, in low-light situations AGC has the ability to increase or decrease exposure. Because the aperture setting has no mid-stops, I recommend the “exposure bias” technique.
  • Exposure Bias Function: The Exposure Bias function can be used when the camcorder is in Shutter Priority mode, Aperture Priority mode, or neither mode (i.e., standard AE operation). Press the "Bright" button and use the setting dial to decrement or increment exposure in 1/3-stop steps. To fully lock exposure, press and hold the setting dial for a second.
  • Run-and-Gun Exposure Setting: In high-contrast situations, nudge the LCD-mounted joystick right for Programmed AE menu. Now select Spotlight mode, which decreases auto-exposure by 2/3 stop. This effectively eliminates burned-out highlights.

For backlit situations, you can press the camera’s "Backlight" button to increase auto-exposure by 2/3 stop.

By pressing the "Backlight" button twice, the camera switches to spot-metered AE. As those shooting widescreen know, the center of your composition is typically unimportant—so JVC enables you to use the joystick to move the spot-meter from the center to either side of the frame. To lock exposure, press and hold the joystick for several seconds.

None of the exposure controls require you to use the camcorder’s system setup menu. Very nice!

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