Tony Davis

Darrell, I'm obviously biased to say that you've hit the nail on the head. I believe that the best way to understand how motion is represented in a motion picture camera (film or digital) is to look at the frequency response of the camera and how that interplays with the sampling (frame) rate. In our literature, we always show this as a modulation transfer function plot with the Nyquist rate displayed. That's some high-mathy lingo to describe a fairly straightforward plot, and when you understand the major axes of it, you see that there's an interplay between sampling, aliasing, and frequency response. Frequency response is entirely determined by the shutter. Usually the only adjustment we have is the shutter angle, which necessarily changes the frequency response. Shorter shutters have higher frequency responses. 360 degree shutters have a rapid falloff (make things smeary and soap opera.) Aliasing is entirely an artifact of frame rate. 24 fps systems can only record visible frequencies up to 12 Hz. That's it. Anything in the real world that is above 12 Hz will get folded in as a made-up frequency between 0 and 12 Hz. That's aliasing, and it's usually considered noise, but one project's noise is another project's fantastic artistic effect (Gladiator, etc.) To reduce aliasing, the frequency response is manipulated. That's one reason the 180 degree shutter looks pretty good. It's got a fair balance of good response below 12 Hz and a falloff above 12 Hz to reduce aliasing somewhat. Short shutters pass a lot of aliasing, and longer shutters minimize it somewhat. So that's the way I look at how cameras work. Digital and film cameras really have nearly identical frequency responses, with the exception that the mechanical shutter in film cameras has a penumbral shadow that causes there to be a very slight ramp in and out of the shutter. That softens the aliasing frequencies very slightly (but not much.) Changing the frame rate will shift up the bandwidth of the system, and 360 degree shutters will still lose response even if the frame rate is higher. It's my belief that a lot of the "cine look" is related to the baseband response of the system. I believe that if effort is made to preserve that frequency band, the look will be preserved even if the frame rate is changed or aliasing is reduced. I actually think the "cine look" can be enhanced this way, but ultimately understanding these concepts will allow artists to have ultimate control over the look of their projects, whatever they choose. Now, our system, the Tessive Time Filter, is just an alternate shutter that ramps in and out in a mathematically determined way to yield a shaped frequency response. It's effectively a temporal lowpass filter to reduce temporal aliasing while preserving frequency response (compare that to an optical lowpass filter to reduce spatial aliasing while preserving sharpness). It doesn't make things look like a 360 degree shutter, and it crams more temporal information into the 24 fps (or whatever framerate you have) without introducing a lot of aliasing noise. This results in a higher signal to noise ratio in the same number of frames. We have footage that shows the effect, and we just got a new batch from an independent test done at Shepperton Studios. There's a writeup and link to the footage at our site: Shepperton Test Footage Anyway, Darrell, we'll be at Cine Gear Expo in New York at the end of the month. Please stop by our booth. I think I at least owe you lunch for correctly identifying what we're trying to do. Thanks, Tony Davis CEO, Tessive www.tessive.com