Any audiophile can tell you about the subjectively superior sound rendition of a tube amplifier over a 'solid state' system. Vacuum tube circuitry just sort of -- bends differently, or more smoothly. In amps, this can produce a more 'organic feel' or effect -- but tubes were also used in video cameras, believe it or not. Due to the ubiquity of chip sensors, an aesthetic consideration like this doesn't have much play in filmmaking these days. Or -- does it? Sundance 2013 award-winner Computer Chess reaches back into the nearly forgotten history of analog, its creators opting to shoot on old Sony tube cameras. Take a tour of the camera, and its use to the film, with cinematographer Matthias Grunsky below.
Said Mr. Tube to the CMOS: "We're Not So Different, You and I..."
Though we normally don't think of things this way, even the most-modern digital cinema acquisition technologies are still basically analog at a very, very important point in the imaging chain -- the sensor. Dalsa, creators of renowned sensor technology, offer a seriously informative pdf pamphlet detailing the major differences in CMOS and CCD design. It isn't exactly new, but it's still a good place to start in differentiating the two primary sensor types.
The key thing to notice about either sensor type in Dalsa's diagrams is the A/D conversion stage, which occurs after our trusty transistors transduce light energy to electrical energy. This transduction is what makes all video acquisition, both modern and aging, possible. But it wasn't always a chip that made it possible -- nor was it always followed by any A/D conversion. Just as our shiny new HDTVs replaced cathode ray tube sets, and many modern guitar amplifiers now use solid-state circuitry, so too were our CCDs and CMOSs preceded by vacuum tubes in video cameras. Which is only slightly trippy.
Vacuum Tubes Do Not Suck
Here is the trailer for Computer Chess, which was shot by Matthias Grunsky on one such glorious dinosaur, the Sony AVC-3260, originally made in the early 1970s.
On his blog, Matthias says:
These cameras would probably have been used for the coverage of an event like this [around 1980]. It has been very difficult to find working black and white tube cameras in the year 2011 but we managed to acquire three Sony AVC 3260 cameras, which were the best option within that sort for giving us a more or less stable signal to record. The Sony AVC 3260 camera’s heart is a 2/3 inch black and white Vidicon video tube.
It came in its original case with all the original accessories and it was like traveling back in time. When I first turned the camera on I felt excitement and fear at the same time -- I was worried as a cinematographer who is responsible for the image produced on this unstable camera, which was not built for shooting features in the first place, has its own life, but on whose performance we had to rely on 12 hours every day.
Here is an exploration of the slightly modified 3260 with Matthias:
One of the things I was wondering most about: how did the crew actually capture footage from the camera? Says Matthias:
Our pre tests showed that the camera’s signal would not run stable enough by itself and we had to run it through a time base corrector before sending it to an analog to digital SDI converter and finally to our AJA Ki Pro Mini which recorded in the Apple ProRes format.
In the case of Computer Chess, the A/D conversion (not to mention some of the image clocking, apparently) took place much, much further down the imaging chain than in today's cameras, that's for sure. Here's one last piece of insight from Matthias, explaining not only why a filmmaker would want to go through all this, but also what the unique difficulties and qualities of a tube camera can lend to the right project. Bringing everything full circle:
These tubes also have a very specific soft character, which would not be easy to recreate in post. The cameras had electronic issues and sometimes would generate electronic noise when touching the camera body or the lens. All these artifacts combined add a transcendental character to the image and help express the sometimes unexplainable things that happen between man and computer in our story.
The quality that such a radical camera choice makes here is immediately obvious. And hopefully, that choice presents another example of how and why, sometimes, lo-fi can be as creatively liberating as it is technically limiting. Huge resolutions and goliath gamuts of color be damned (but only sometimes.)
As as a bit of a side note: it would certainly be interesting to see where tube camera technology would be today, had engineers and manufacturers never ended development along such lines. Anyone qualified in electronics is encouraged to entertain that idea! Everyone is also encouraged to check out Computer Chess, and head on over to Matthias's blog, where there's a lot more info for those interested.
Links:
- Computer Chess -- Homepage
- "Computer Chess": a more detailed look at the tube camera -- Matthias Grunsky's Blog
- Video camera tutorial for the Sony AVC-3260 -- YouTube
- CCD vs. CMOS: Facts and Fiction -- Dalsa
