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In my last review of Sony's 3-CMOS HVR-V1U (see digitalcontentproducer.com/cameras/revfeat/sony_hvrvu), I sketched the V1's pedigree, layout, operation, and unique features. In this article, I'll tackle the V1's image quality and new opportunities in high-quality image capture made possible by the V1's HDMI output and Blackmagic Design's new Intensity HDMI capture card.
As noted in my last article, the V1 is a complex imaging system with myriad setups and results. So I won't attempt the forensics of every picture profile, a topic better left to the intersection of technique and taste. Rather, I want to convey a broader sense of how this unique 3-CMOS camcorder is different from the 3CCD camcorders we've grown accustomed to since the late 1980s.
Every image from the lens of a digital camcorder is spatially sampled by a pixel-based imager; then converted from analog to digital; then encoded into video components for signal processing; then compressed by a codec for recording to tape, disk, or flash memory. Sony's V1 introduces key innovations at each of the first three steps.
As noted in a previous look at the V1 (see digitalcontentproducer.com/hdhdv/depth/sony_hvrv1u_09192006), Sony's 16:9 1/4in. ClearVid CMOS chips, 1 megapixel each, use a novel pixel grid that's tilted 45 degrees. Pixels, in other words, are diamond-shaped instead of square. Why on earth would Sony do this?
Briefly, in a CCD, charges accumulate at each pixel (photodiode) during exposure. To create an analog voltage for output, charges are then transferred out one column (or row) at a time in strict ordinal sequence with precise timing. As passive collectors of photoelectric charges, CCDs are, therefore, dumb devices. They're basically an area array of incident light meters. (Remember those?)
Unlike CCDs, which emerged from advanced computer memory research (Bell Labs, late 1960s), CMOS evolved from common integrated circuit (IC) design. The idea behind CMOS was to create a simpler, cheaper (theoretically), and smarter imager, with built-in A/D and signal processing located at every pixel. This is why CMOS is sometimes called "retina on a chip." (The eye's retina is actively part of the central nervous system.) Unlike CCD pixels, whose accumulated charges are marched out of a CCD's pixel architecture like soldiers in single file, CMOS pixels are individually and randomly addressable, and they're output...