Digital Cameras

Our December 15 Meeting at Video/Visuals

By Robert Lamm

The presenters almost outnumbered the audience at the Dec. 15 meeting on new camera technology. Itís a shame too, it was a great meeting:

Dave Mewhinney, Panasonic

Digital Processing

Dave showed off Panasonicís new AK- series digital processing video camera, and gave a quick overview of the latest developments:

Although camera sensors generate analog signals, sampling these signals and processing them digitally makes camera colorimetric adjustment much simpler, faster, stabler and repeatable. The cumbersome setup process is completely eliminated because digital circuits can instantaneously sample and readjust the cameraís parameters to conform with the requested settings. And the number of parameters which the user now has control over has multiplied too. All these settings can be stored in ROM for later use or copied from camera to camera, resulting in perfectly matched sets. Drift, whether due to temperature, aging or whatever is completely eliminated.

Dave went over some of the technical details: Analog RGB signals from the sensors are sampled at 14.31818MHz (4fsc) at 8 bits/sample. The digitized signals are analyzed, and feedback loops control the gain (camera sensititivy), black/white balance (basic colorimetry), flare (adjustment for lens artifacts) and shading (adjusting for uneven sensitivity across the image plane) of the analog circuits that precede digitizing. The remainder of the processing: knee slope (how bright whites are reproduced), gamma (how greys are reproduced), contour correction (artificial sharpening), matrix masking (making the cameraís colorimetry mimic the eyeís), cross-color suppression (preventing color and luminance detail from affecting one another) and encoding (making RGB into composite video) are performed digitally.

Dave pointed out that digital circuits have provided capabilities previously unheard of, such as separate circuits for white, black and flesh detail, two-dimensional cross-color filters with very narrow notches that prevent fine detail (like tweed coats) from strobing but don't degrade resolution, and shading across 4320 zones! From a user's point of view, the most significant development is the ability to store all these settings and recall them later or in other cameras. Matching all the cameras on a production is simply a matter of sending them all the same settings.

Dave also showed off Panasonic's a new fiber-optic digital transmission system: The signal can be carried for up to 24 miles without amplification if the camera is locally powered. (The copper leads in the cable limit power transmission to a mile and a half.) Unlike more conventional triax, fiber optic signals arenít affected by stray signals. Dave mentioned the coverage at the Indy 500, where cameras were able to get closeups of the motors without static from the unprotected ignitions.

Brett Lukezic, Sony

World's First All-Digital Camcorder

Sony is filling in the gaps in its Digital Betacam line with the DVW-700 one-piece Digital Betacam camcorder. Mr. Lukezic passed one around, and we were very impressed: It weighs less than 16 lbs, has a well-thought out design, and a long-lasting battery.

It's the small details that count, and one that we appreciated was a special tape loading mechanism that makes it hard for dust to get into the mechanism or the cassette. We also noted that the DVW-700 runs very quietly. And we liked the extended clear-scan that makes it possible to shoot computer CRTís without flicker. But the feature we liked most was the long battery capacity: The camcorder had been on since 6:30pm, and was still perking along two hours later.

Some of the digital processing technical parameters are a little different: 10-bit sampling is performed at 35MHz. Brett took the cover off the camcorder to show us how highly integrated the electronics are: Most of the processing is performed by five huge chips. The scanner is half the normal size: It rotates at half the RPM and has twice as many heads on it. This and some acoustic barriers are what make the camcorder so quiet.

The only bad news is that you can't record conventional Betacam with the DVW-700. For that you need to get a separate camcorder called the BVW-D600.

Brett also spoke a bit on Sony's studio camera line. They come with switchable optical blocks: a regular 4:3 assembly can be quickly replaced with a wide-screen 16:9 one. They can also be upgraded to digital output with board swaps.

Chris Taylor, BTS

Studio Cameras

Chris Taylor was in a great mood. He had just sold cameras to WCVB and WSBK-TV. BTS studio cameras use Frame-Transfer sensors, requiring the use of mechanical shutters, but the pictures were gorgeous. The larger pixel area on Frame Transfer chips results in less aliasing and more sensitivity. The dynamic range is so great that the cameras donít have color-temperature filters: Color balancing is done electronically. BTS cameras also have lots of nice adjusments on them, such as multiple flesh-color detail adjustments, allowing you to adjust the camera response for each person in the scene, even if theyíre in the shot simultaneously.

BTS also has a unique way of dealing with 16:9: They throw away the top and bottom parts of the picture to generate the widescreen image. (Others augment the 4:3 image with sidebars.) The same chip is used, so BTS cameras can generate these regular and widescreen images simultaneously. The fact that the horizontal angle of view is the same on both outputs makes it easy to design a production for both screen proportions.

Dave aimed the camera at me and Phil Ozek, and demonstrated some of the sophisticated colorimetric features. He claimed that he could make us look younger, but I noticed that he didnít put any additional hair on either of our heads. What about it, Chris?

I should mention the hospitality of Video/Visuals, which hosted the meeting and provided mucho munchies. Bob Lewis, the owner, gave us a grand tour, including his new component editing and AVID suites. And Iíd like to extend a special thank-you to the presenters for coming up to such a small audience, yet enduring all dopey questions that I asked. Hopefully, weíll have a bigger audience next time...

Bob Lamm is Manager at CYNC Corp., a video dealership in Brookline, MA. He can be reached at (617) 277-4317, cync@world.std.com.