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MillimeterShoot Review — JVC GY-HD100
Nov 1, 2005 12:00 PM, By Steve Mullen
Three-CCD camcorder shoots true 24fps, 720p HDV.
JVC’s compact new GY-HD100 shoots true 24p HDV and accepts 1/3in. interchangeable lenses directly (a 16X Fujinon is included).
It is a decades-old dream of many filmmakers and videographers to use a camcorder to shoot progressive (24p or 25p), high-definition video that can be transferred to 35mm film. The 720p HDV format has made it possible for this dream to be realized at a very low cost.
Of course, growing numbers of those shooting corporate, news, government, religious, and event videos are also interested in shooting progressive HD video, although not necessarily at 24fps.
For both types of shooters, the JVC GY-HD100 is a nearly perfect 720p HD solution. Not only is it inexpensive, at less than $6,300, it has three characteristics that make it unique in its class. First, the HD100 captures true 24p HD video. Second, the HD100 looks, feels, and behaves much like a film camera by providing exactly the shooting controls one needs and by dispensing with consumer-oriented gimmicks like sepia tone. Moreover, for those who are used to shooting with professional SD/HD video camcorders, these controls are exactly where you would expect them to be.
Finally, the GY-HD100 also has a very complete array of camera setup controls that will be familiar to those who use expensive SD and HD camcorders. Among these controls is the choice of multiple modes of shooting.
Shooting 24p
To shoot true 24p, switch to 720/24p and keep the shutter speed at 1/48 second. When you shoot 24p you can disable the JVC-designed Motion Filter. Now you must shoot as you would film in order to avoid introducing motion judder. If you are not familiar with these procedures, feel free to enable the Motion Filter. When the Motion Filter is disengaged, every other frame is discarded. (When the filter is engaged, every two frames are processed to create one frame.) When shooting 24p, the camera outputs 48p with a 1:1:1:2 pulldown to 60p as an analog component signal.
Six frames are encoded into one GOP. Then one or two Repeat Flags are inserted between each pair of encoded frames. Through this process, six frames are converted to 15 frames — six frames of which are encoded video frames and nine of which are Repeat Flags.
The pattern by which the frames are generated is a familiar one — 2:3:2:3:2:3.
Each second of video is converted to four GOPs. When the Repeat Flags are included, 60 frames are generated. Therefore, the recorded timebase is 720p60, although only 24 video frames are recorded to tape. When the tape is played, for analog component output, each frame is decoded. When a Repeat Flag is encountered, the last frame is output again. If a second Repeat Flag is encountered, the last frame is output again once more.
Upon IEEE 1394 capture, NLEs can discard the Repeat Flags and store 24p video to disk. Or they can store the 720p60 to disk and then use reverse 2:3 pulldown to obtain 24p video.
Shooting HD HDV
To shoot HD video, switch to 720/30p, engage the Motion Filter, and keep the shutter speed at 1/60 second. The Motion Filter eliminates the background and foreground strobing present with 720p30 shot with the JVC HD1 and HD10.
In 720p30 mode, the CCDs capture 720p60 video. (The 4:2:2 sampled uncompressed 60p video is output as an analog component signal.)
When the Motion Filter is engaged, every two frames are processed to create one frame. (When the filter is disengaged, every other frame is discarded.) Six frames are encoded into one GOP. Then one Repeat Flag is inserted between each encoded frame.
Thereby, each second of video is converted to 60 frames. The recorded timebase is 720p60, although only 30 video frames are recorded to tape.
When the tape is played, for analog component output, each frame is decoded. When a Repeat Flag is encountered, the last frame is output again. Upon IEEE 1394 capture, NLE software can discard the Repeat Flags and store 30p video to disk.
Shooting DV and SD HDV
The GY-HD100 can shoot 480i60 DV if you switch to DV-60I mode. You can choose to shoot with either a 4:3 or 16:9 aspect ratio. You can also shoot 2:3:2:3 pulldown (DV-24P) or 2:3:3:2 pulldown (DV-24PA). Likewise, the HD100 can shoot 16:9 SD 480p60 HDV if you switch to HDV-SD60P mode.
GY-HD100 Features
The HD100 is compact (9 1/4"×9 1/8"×12 3/8") and weighs only 6.9lbs. with lens, viewfinder, mic, battery, and tape. The bundled BN-V428 battery has only about a 30- to 40-minute record time. An optional BN-V438 offers up to 60 minutes. You can also purchase a battery mount for both IDX and Anton Bauer batteries.
The camera body includes a slide-out shoulder mount. The included viewfinder has twin adjustments. It can be slid left or right. In addition, the eyepiece can be slid in and out. The VF has a 230,000-pixel color LCD. It features three controls: peaking, brightness (black level), and contrast (white level).
The flip-out 3.5in. LCD provides 250,000 pixels and also has contrast and brightness controls. (Brightness and contrast controls are necessary for VF/LCD calibration.)
Audio Functions
Two XLR connectors are available for the input of mic level (switchable between -50dB and -60dB) with or without +48V phantom power and line level (+4dB). The HD100 has both 1/8in. and 1/4in. stereo jacks for earphones and a clever, adjustable ear-level speaker.
The Channel 2 input can be switched to clone Channel 1 if you desire. You have both Auto (limiter only, not AGC) and Manual audio level options. HDV audio is sampled at 48kHz (16 bits) and encoded using MPEG1, Layer 2 audio (MP2) at 384kbps. Channel 1 (only) is also recorded — unfortunately way too hot — as PCM DV audio.
To capture this audio, with the camcorder off set the HDV/DV switch to DV. Connect a 1394 cable and power up. Now set PB TAPE to DV. Press Play and, only when you see the MPEG-2 data “confetti,” start capturing 48kHz DV.
Video Functions
The side-loading tape transport accepts MiniDV tapes. VCR mode allows the usual transport control functions.
A complete set of camera controls are provided: 1/4 ND, 1/16 ND, 30p shutter speed (1/7.5 through 1/1000 plus Variable), 24p Shutter Speed (1/6 through 1/1000 plus Variable), Zebra on/off, Timecode Display (TC/UB), Timecode Control (FREE, REC, REGEN), Status Display, Audio Monitoring, and Full Auto (auto audio, auto gain up to the ALC limit, auto exposure, and FAW that provides full-time auto white balance).
Menu System
The GY-HD100 features multiple setup menus. The first menu set provides fundamental video settings including Frame Rate (60/30, 50/25, and 24), Record mode, and Aspect Ratio. Here you also set the playback (PB TAPE) mode to AUTO, DV, HDV, or DVCAM.
Three RCA jacks are provided for both SD/HD composite and component output. HDV and 16:9 DV are output via a composite connection as anamorphic video. Unfortunately, no S-Video output is available, which essentially prevents high-quality dubs from HDV to an SD format.
When using analog component connections, DV is output only at 480i60 while HDV can be output at 480p60, 720p60, or 1080i60.
The IEEE 1394 port can be switched between DV and HDV circuitry. When the HD100 is recording as a VTR, only HDV is accepted with the switch set to HDV — and only DV is accepted with the switch set to DV.
When playing an HDV tape, only MPEG data is output. No HDV-to-DV downconversion function is provided. JVC recommends editing in native HDV and only then downconverting to SD.
During shooting, the BNC jacks output — with no delay — 4:2:2 uncompressed video. (When shooting 24p, the camera outputs 48p with a 1:1:1:2 pulldown to 60p.)
Likewise, during shooting, the IEEE 1394 port outputs either HDV or DV. The 1394 port supports the Focus Enhancements FireStore DR-HD100 (40GB and 80GB). Direct-to-Edit technology means that DR-HD100 files are recorded in the HDV/DV editing system's native file format.
The second menu set provides access to controls that will be familiar to most video shooters: AE bias, Maximum ALC gain, the color temperature assigned to the Preset WB switch setting, Smooth Transition (when gain and white balance are switched), and color bars on/off.
The third set provides access to Master Black, Detail, Black Stretch/Compress, White Clip (100 IRE or 108 IRE), Knee (AUTO or 80 percent to 100 percent), and Smooth Motion enable/disable.
I found I achieved maximum latitude in very high-contrast conditions by enabling Black Stretch 2 and setting the Knee to 80 IRE. With these settings, the apparent latitude is the best I have ever encountered with any camcorder with 1/3in. CCDs.
You have extensive control over image detail. You can set the horizontal and vertical balance of which contours (detail) to sharpen. Settings range from H-MIN through NORMAL through H-MAX. Detail can be adjusted, and you can also individually determine the detail compensation frequency for horizontal and vertical contours. Lastly, you can set the amount of softening for the Skin Detail function.
You will also find the Advanced Process options on this menu. The first menu item turns CINELIKE mode on/off (use when you desire a film look). Turning on CINELIKE mode automatically selects the Cine Color Matrix and Cine Gamma. You can adjust Cine Color Matrix and Cine Gamma to your tastes.
Turning off CINELIKE mode, you can control the camera's color matrices and gamma level. There are three color matrices that can be selected: STANDARD (adjustable Video Matrix), CINELIKE (adjustable Cine Matrix), and Off (a non-adjustable ITU 709 Video Matrix). When either STANDARD or CINELIKE is selected, you can — for Red, Green, and Blue — adjust Color Gain and Phase individually for the Video Matrix and Cine Matrix.
There are three types of gamma that can be selected: STANDARD (adjustable Video Gamma), CINELIKE (adjustable Cine Gamma — for use when you desire a film look), and FILMOUT (use only when shooting for film and when you have monitors that can display this gamma).
Color Gain can be adjusted to OFF (B&W) and to -10, NORMAL, 0, and +10.
You can vary the AWB on two dimensions: White Paint
The Skin Color Adjustment allows you to select the color of the skin and to set the range around this color to which the skin detail reduction filter will be applied.
The fourth menu set provides access to Shutter mode, Full Time White Balance (FWB), and the level of gain (ALC, 0dB, +3dB, +6dB, +9dB, +12dB, +15dB, and +18dB) associated with L, M, and H switch position.
CCD and DSP
Although the GY-HD100's CCDs and DSP are both very sophisticated, they are simple to understand. That is because they provide a 1280×720 CCD resolution that is exactly equal to the resolution of the 720p recording format. Neither scaling nor de-interlacing is required.
The GY-HD100's DSP chip features 12-bit A/Ds and a math unit that performs calculations using 24-bit words.
Fujinon Optics
The HD100 can accept a 1/3in. interchangeable lens directly or, via an adapter (not included), a 1/2in. lens. I tested the camcorder with the bundled 16X Fujinon Th16×5.5BRMU. Its zoom ranges from 5.5mm to 88mm. Over the range 5.5mm to 68mm, the maximum F-stop is F1.4. From 68mm to 88mm, the maximum F-stop is F1.8. However, the T-stop (actual light transmission) is T1.5 over the entire zoom range. In Macro mode, the minimum object distance decreases from 1m to .01m.
Manual zoom is smooth, and variable-speed electric zoom offered a 3- to 15-second speed range. The manual iris is very precise. I found that I could achieve spot-on exposure simply by momentarily pressing the AE button on the lens. The best characteristic of the lens was the direct — non-servo — focusing ring.
Lateral Chromatic Aberration was visible (magenta on one side and green on the other side) on high-contrast objects.
Naturally, achieving precise focus is critical to minimizing chromatic aberration. I assigned the Focus Assist (FA) to the RETurn (Review shot) button on the lens. Using FA, as the image becomes more focused the sharp edges of objects take on a more intense color (red, blue, or green).
Conclusion
Clearly, I think very highly of JVC's GY-HD100. When shooting 30p, your video — especially if you punch up color — has the “realistic” look of 720p60. Yet, because of JVC's excellent colorimetry, it does not look like “high-resolution DV.”
For those shooting 24p, the judder (if you want it), low temporal rate, slightly increased motion blur, and colorimetry all combine to create the look of film. Moreover, the inclusion of the FILMOUT gamma enables you to, for the first time for less than $50,000, shoot HD 24p video intended from the start to be transferred to film.
The GY-HD100 offers so much image quality and control, it makes one want to become a much better shooter.
BOTTOM LINE
Company: JVC
Wayne, N.J.; (973) 317-5000
Website: pro.jvc.com
Product: GY-HD100
Assets: Shoots true 24p, professional interchangeable lens, extensive array of camera setup controls.
Caveats: Split Screen Effect is a potential hazard at low light level. Short battery life.
Demographic: HDV shooters especially interested in 24p production.
Price: $6,295
About High-Speed Twin-Readout CCDs
The DSP Chip of the JVC GY-HD100 features six 12-bit A/Ds. Why six rather than three A/Ds? The three CCDs of the HD100 capture 720p60 video. Each row has 1280 elements. If JVC had tried a design that directly captured 1280 pixels over 720 rows 60 times per second, the clock rate driving the CCDs would have had to be more than 55MHz (1280×720×60).
The faster the clock rate, the greater the heat generated, and the more heat that must be dissipated. This level of heat is no problem for a 2/3in. CCD, but it becomes very destructive in a 1/3in. CCD. JVC's solution is a HSTR (high-speed twin-readout) chip. HSTR provides every CCD with dual ports so that a pair of analog values can be read out for each clock pulse. The result is that the clock rate is cut in half and heat becomes manageable.
All CCDs have a linear transfer function that describes the conversion of input light level to output voltage. A light range of 0 to 100 percent (total saturation) is mapped to 0 to 100 IRE. CCDs may have, at the low end of the light input range, a “nonlinearity” (a tiny step) in the linear function. For example, light levels beginning at 15 percent yield IRE values of 17 to 102 IRE rather than 15 to 100 IRE.
Given the HSTR design of the HD100 chips, there are naturally two transfer functions for each CCD. If the output from one half of the CCD is within a range of a nonlinearity and the other half is not, the difference may be manifest as the right and left sides of the image varying slightly in brightness — the so called Split Screen Effect (SSE).
Initially, the Internet was buzzing with reports of SSE because the initial production units imported only by Region 50 countries had not undergone the advanced calibration process that all HD100 units undergo when imported into the U.S.
Because a nonlinearity is typically only a few IRE, it is not visible when an adequate signal range is input. Under low illumination, as an SSE precaution, I set zebra to 70-80 and then add light and gain so faces or white objects have zebra. If necessary, I set gain at +6dB (when major portions of the image are dark) or +12dB (when the picture contains a minimum of dark areas).
