Reviewing Sony HVR-V1U HDV Camcorder
Sony shooters have long wanted an HDV camcorder that records 24p video. In December 2006, Sony began shipping the Region 60 HVR-V1U HDV camcorder. The V1 is relatively small and lightweight: 12.8"x7.2"x5.2i" and 3.6lbs. The MSRP for the HVR-V1 is $4,890.00.
The HVR-V1U employs three 16:9 3ClearVid CMOS sensors; each 1/4in. chip has 1.03 million effective pixels. The chips are always progressively scanned at either 60Hz or 48Hz (Region 60) or 50Hz (Region 50). Unlike other CMOS chips, 3ClearVid features elements that have been rotated 45 degrees.
A 3ClearVid chip has 1080 staggered rows. Each row has 480 elements, so each pair of rows has 960 elements. Likewise, the chip has 960 staggered columns. Each of the staggered columns has 540 elements, so each pair of columns has 1080 elements. The chip's diamond pattern allows the distance between elements to
be smaller, thereby increasing spatial resolution. According to Sony, four elements-from four columns-are read simultaneously from each 3ClearVid chip into each of the EIP's three 2-million-cell buffers. By outputting four elements at a time, read-out speed is increased by a factor of four, thereby significantly reducing the
The output from the 3ClearVid chips is an analog signal that is converted to digital by a 14-bit A-to-D converter in the Digital eXtended Processor (DXP). The DXP chip uses 14-bit words for baseband signal processing. Sony''s 3ClearVid technology is tightly integrated with Sony''s Enhanced Imaging Processor (EIP). According to Sony, the EIP works at 1920x1080 in a 4:2:2 color space. The EIP has a 2 million-pixel buffer for each of the three primary colors. Traditionally the image sensor is considered the device in which an image forms and from which it is captured. I consider the 6 million-cell EIP buffer to be the V1''s “virtual sensor.”
After each capture from the CMOS chips, each buffer has 1 million samples — leaving 1 million buffer cells empty. Interpolation is used to fill the 1 million empty cells in each EIP buffer. According to Sony, interpolation is performed by calculating the average value of the four adjacent CMOS samples. Sony''s diagram, below, shows four empty cells (red dots) filled by using the four samples (open circles) on all sides of empty cells. The result is four calculated pixel-filled circles. (A
1.33:1 pixel aspect-ratio supports the 16:9 chip aspect-ratio.)
After interpolation, each buffer row has 1920 data points, composed
of 960 CMOS samples alternating with 960 interpolated pixels. Line 2
Each synthetic (interpolated) pixel contains information from adjacent samples, making them spatially “wider,” thereby reducing the resolution of these 960 pixels. Nevertheless, they enhance the horizontal resolution of each video line, as they're created from a mix of synthetic pixels and CMOS samples. Before MPEG-2 encoding, each line is scaled from 1920 to 1440 data values. After encoding, 60 fields per second are recorded to MiniDV tape (or to hard drive).
Likewise, after interpolation, each column has 1080 data points,
composed of 540 CMOS samples alternating with 540 synthetic pixels.
Line 2 is shown.
Each synthetic pixel also contains information from adjacent upper
and lower samples, making them spatially "taller," thereby
reducing the resolution of these 540 pixels. Nevertheless, they enhance the vertical resolution of each video column, as it is created from a mix of synthetic pixels and CMOS samples. I'll discuss resolution more when we look at the V1''s performance.
An example of EIP manipulation is 24p recording, where the camera switches to a 48Hz scanning rate. Every other capture is discarded, yielding 1920x1080p24 video. Using industry-standard 2:3 pulldown, every four progressive video frames become 10 interlaced video fields. In this way 24p is “carried within” 1080/60i video. Two “judder” frames are generated that contain one field from one frame and one field from an adjacent frame (represented by the red text in the Table below.)
When you watch 24p video, you see a mix of 24fps motion judder and 2:3 cadence judder — just as you do when watch film converted to video using 2:3 pulldown.
The V1 offers two 24p modes: one for those who plan to edit a 24p production using an NLE, and a mode for video shooters who want 60i video with 24fps motion judder. The first mode, “24A,” forces every clip to begin with an “A” frame. When playing 24A, brief pauses may occur at the end of clips. To prevent pauses, the latter mode, “24” mode, does not force clips to begin with “A” frames.
Ideally, your NLE will have the capability to remove 2:3 pulldown. Currently, only Sony Vegas 7, Grass Valley Edius 4, and Adobe Premiere Pro 2 with CineForm''s Aspect HD can do this. Vegas supports native HDV editing, while Edius and Premiere support intermediate codec editing. (I used both Vegas 7 and Edius 4 to edit 24p with the Sony V1U.) Of course, you can also edit 24p video as 60i video, but you should
avoid cuts that begin with judder frames. I used this process with
FCP to create a 1080i60 (with 2-3 pullup) red-laser disc that plays
on HD DVD players.
To record 30p, the V1U discards every other 1920x1080p60 frame. The odd and even lines of the non-discarded frame are encoded and recorded as consecutive fields. When these fields are viewed as frames, they will have 30fps motion judder.
The V1''s Carl Zeiss Vario-Sonnar T* lens has a filter diameter of 62mm. The lens has a bayonet-mount sunshade with lever-operated lens cover, and it uses extra-low-dispersion glass. The f-stop range varies from 1.6 to 2.8.
The lens has a 20X optical zoom. The range is from 3.9mm to 78mm, for a 35mm equivalent range of f=37.4mm to 748mm (16:9) or f=45.7mm to 914mm (4:3). While news and nature photographers will appreciate the 748mm telephoto capability, those shooting in tight places will find a 37.4mm wide-angle to be inadequate. (When working with a 35mm camera, a 28mm or 24mm lens is considered “wide.”) The zoom range can also be extended digitally by approximately 1.5X to reach the equivalent of 1100mm for a 35mm camera. The digital zoom does not appreciably degrade the HD image.
A wide lens ring controls focus using servo control. Sony's Super SteadyShot OIS is employed for image stabilization. A switch on the side of the lens selects between “none” and a 1/4 or 1/16 ND filter. Zoom is controlled via servo control from a vari-speed rocker control, a handle multi-speed rocker, and a perpetual lens ring.
The exposure dial can be defined to control iris from F1.6-F11, to bias the automatic exposure using AE Shift, or to provide multi-function exposure control. AE Shift mode works extremely well for run-and-gun shooting because you can make quick alterations to AE-determined exposure as you monitor using the histogram display. By the way, in the vast majority of situations, I found the AE system to be spot-on. By setting AE Response to Slow, the AE system will smartly ignore brief illumination fluctuations and yet make smooth transitions when light levels change. When using AE Shift mode, be aware that if you leave this mode, the last shift value continues to alter exposure.
When you use Exposure 1 or Exposure 2 modes, you need to be aware that the Shutter-Speed button (E1 mode) or Shutter Speed and Gain buttons (E2 mode) are “locked,” preventing you from using these controls. However, until you press the Manual Exposure button, the camera is in AE mode and shutter speed (E1) or shutter speed and gain (E2) will be altered by the camera as it optimizes exposure.
The V1 does, however, attempt to use the default shutter speeds based upon the chosen frame-rate: 1/60 for 60i/30p and 1/48 for 24p. To minimize the possibility of the unwanted shutter-speed and/or gain changes, set AGC (automatic gain control) Limit to +12dB and AT Iris Limit to F5.6. Remember to confirm the current shutter speed and gain are correct before pressing the Manual Exposure button—which actually does “lock” shutter-speed (E1) or shutter-speed and gain (E2).
Between the CMOS sensors and its Enhanced Imaging Processor (EIP), Sony''s HVR-V1 has two very welcome attributes: superb latitude and no vertical smear.
Minimum illumination is rated at 4 lux, only 1 lux lower than the CCD-based Z1. Traveling in Asia, I found the V1''s low-light capabilities to be very acceptable. For example, note the visible movie screen in the upper-left corner of the screenshot of a restaurant in Malaysia at night. The screen in reality was very dim.
Video gain can be set to 0, 3, 6, 9, 12, 15, and +18dB. Because noise is typically visible only in medium-dark areas, there
is no simple relationship between gain and noise. By engaging Black Compress or Cinema Gamma 1, you can push these areas to black, removing noise from the frame. I found I could use +9dB gain without adding noise – although in many situations I used +15dB, as shown below.
Steve Mullen owns Digital Video Consulting that offers eBooks on HD production. Currently, DVC (www.mindspring.com/~d-v-c) offers two eBooks: the Sony HDV Handbook and the JVC ProHD Handbook. This month, DVC will offer a new title: the Sony V1/FX7 Handbook. And in June, DVC will release an eBook on low-cost high-definition DVD creation.