16 Megapixels Drive Camera Back
Brent D. Johnson
Traditional full-frame image sensors did not offer Phase One's professional camera customers the photoresponse that they required for their work. The traditional CCD's polysilicon gate structure absorbs too many of the incoming photons, which makes it difficult to crop and resize images.
More pixels, better sensitivity in the short-wavelength visible range and lower electronic noise made the Kodak KAF-16801CE image sensor the top choice for the Phase One H 2O camera back.
Phase One's new LightPhase H 20 camera employs a Kodak 16-megapixel camera back that allows professional photographers the dynamic range they need to capture, edit and resize images with the ease that most amateurs are now realizing with lower-resolution digital cameras.
The Kodak KAF-16801CE CCD image sensor was specifically targeted for fashion photography and high-end advertising agencies. It is a large 4/3-in. piece of silicon -- six times larger than the 1/2-in. CCDs found in typical consumer digital cameras. The device relies on the Blue Plus family of sensors that substitute indium-tin-oxide transparent gates for polysilicon, resulting in a response that is increased by a factor of 10 at 400 nm and 50 percent at 600 nm.
The altered pixel architecture and manufacturing controls have reduced the inherent electronic noise in the chip, so cooling is not required. Phase One's executive president, Carsten Steenberg, said that, to reduce noise even further, the device uses intelligent power management, which permits the camera to run much cooler. The way it works is that, except for the CCD, the system is turned off when not needed. The components power up very rapidly, so the entire system is running only for 1/25 s at a time. This reduces the heat that would occur in a system that was always running. Passive cooling also allows features like a 30-s frame exposure, which, Steenberg said, is almost unheard of in these kinds of systems.
The only weakness of the Kodak CCD, said Steenberg, is that it takes a little bit longer to empty the pixel well of the electrical charge. He said that it must be emptied by column. It takes about 5 ms before the pixels have a clean slate so they are ready to capture again.
Phase One is in the somewhat awkward position of competing directly with the Kodak Professional Div. Steenberg said that although his company has an excellent relationship with Kodak Imaging, it is in fierce competition with the Kodak Professional unit, which produces the Kodak DCS Pro Back camera based on the same CCD chip.
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