This page discusses the discontinued Time Filter product.  For our latest approach to better motion representation, please see our Time Shaper solution.

 

The Tessive Time Control system is a completely new way to correctly represent action in motion picture cameras, so naturally we receive a lot of questions about it.  Here we try to answer the most common questions.  Please contact us if you have a question; we'd be glad to talk to you.

What is it?  How does it work?  What does it do?

The Tessive Time Filter is an accessory for professional motion picture cameras that substantially improves the representation of motion.  The improvement is an in-camera effect.  Really, it's a supplemental shutter for the camera that attaches in front of the lens and smoothly shapes the amount of light allowed to expose the sensor over the course of the time of each frame.  A normal shutter transitions instantly from dark to light and later from light to dark.  The Tessive Time Filter has a smooth, graded transition both directions.  That's really it.  

If we want to get really specific, the Tessive Time Filter is an analog lowpass prefiter in the time domain to prevent temporal aliasing.  But, at Tessive, we find that when we say that sentence, people start checking their watches and remembering important things to do somewhere else.  So we put all that kind of talk on a different page:

Time Filter Technical Explanation

Bottom line, it makes wagon wheels go the right way around and fast moving things look...better.  You strap it on the camera, sync it up, and it stuffs more good information into the footage (and eliminates the bad stuff.)  

To really understand what this system does, watch this video:

Is the Time Filter the same as a mechanical shutter, like the shutter on a Sony F65 or ARRI ALEXA Studio?

No, the Time Filter is doing something very different than a mechanical shutter.  For a better explanation, we've performed a full test of our shutter comparing it with the mechanical shutter on the Sony F65. See our explanation and results at the following page:  

How can I get one?

The Time Filter is no longer available for purchase.  You can rent them from The Camera House in Los Angeles (www.thecamerahouse.com).  

What's in the box?

Transient

The Time Filter system includes the Time filter itself (4 by 4 inch or 4 by 5.65 inch sizes), the controller, a calibration wand, an AC adapter, a DC power cable (option of D-Tap, RED Accessory power, or flying leads), Time Compensator software, manual and calibration info all in a hard carry/shipping case.

In addition, the kit includes a filter holder modified to allow cable passage. When you order a Time Filter, specify the matte box or filter holder you'll be using, and we'll provide an original equipment filter holder that has been modified.  We've supported most of the major matte box makes, including Arri and RED.  The filter is a normal size, but it's obviously unusual to have a cable coming out of the filter, so we make it easy by providing a holder that accommodates this.

The Time Filter includes a 1 year warranty against manufacturing defects.

If I want smearier images, why can't I just use a 360 degree shutter?

Strictly speaking, the Time Filter doesn't make smearier imagery.  If you check out the frequency response of the fully compensated Time Filter, it is actually sharper than a 180 degree shutter, and much, much sharper than a 360 degree shutter.

The figure below shows the whole story.  The way to read this is to look at the graph as two regions split by something called the Nyquist Frequency.  For 24 frames per second, the Nyquist frequency is 12 Hertz (half the frame rate.) Below that frequency, we want as much response as possible (so higher is better, higher response means less smeary imagery)  To the right of that dashey line, we don't want any response at all; this is where aliasing noise comes from (so this is bad.)

The blue line is the response of a normal 180-degree shutter.  Not too shabby below Nyquist (we call this region "baseband," but then we like to name things during our lunch hour.)  But things get nasty above Nyquist.  There's lots of response up here, and that's bad.  That's backwards wheels and stuff going crazy in our footage.  The green line is the 360 degree shutter.  It's response in baseband (below Nyquist) is terrible.  This is the smeariness you see in 360 degree shutter footage. But, see, it's still bad above Nyquist.  It aliases (we think that's a raw deal.)

It turns out that as long as you have sharp transitions between shutter open and closed, you never have a good way to choose between baseband sharpness and lower aliasing.  So that's where the Tessive Time Filter system comes in.  Look at the red line:  sharper baseband response than even the 180 degree shutter while having sharply reduced aliasing above Nyquist.  So it's higher in the region where it should be high, and it's lower in the region where it should be low.  This is why we say the Time Filter system makes motion both crisper and smoother.

Is this the same as those motion enhancement filters you can use on new high definition displays?  Can't I do this in postprocessing?

No!  This is actually something very different.  Aliasing is a phenomenon that can only be analytically and correctly fixed during acquisition.  If imagery aliases during acquisition, no ordinary and mathematically stable filter can fix it in post.

As an example, think of aliasing in another dimension.  Spatial aliasing is something digital camera folks are very used to:  Moiré patterns.  What gets rid of Moiré patterns in an image after it's been acquired?  Not much.  You can blur it in post like crazy, but you lose a lot of information.  In high quality digital cameras, there is always a carefully designed optical lowpass filter (OLPF) right in front of the sensor to eliminate this effect before acquisition happens.  The Tessive Time Filter is a lowpass filter in time for exactly the same purpose.

Are you saying that normal camera shutters are mathematically (physically/ethically/morally) wrong?

Not exactly.  We're saying that normal camera shutters are limiting in certain ways.  If the goal is to have less aliasing, then the very limited adjustment of just shutter angle isn't going to get you there—at least not without sacrificing lots of crispness of real motion.  We're simply offering a new adjustment that hasn't existed before, and demonstrating that in most situations it creates a desirable effect.  We back that up with math and data that show that we're not completely crazy, but the proof is in the footage.

How about "rolling shutter" effects?

Most modern digital cinematography cameras exhibit "rolling-shutter" artifacts.  This is because the top of the frame is read out at a different time than the bottom of the frame.  If you do a quick pan past vertical things in the frame, they'll appear to lean to one side.  The Tessive Time Filter, however, is simultaneous across the entire frame, so when attached to a camera with a rolling shutter, it will eliminate these artifacts.

By the way, the Time Filter has many modes of operation, one of which is to create a simple 180 degree shutter.  If you set your camera to 360 degrees, then the Time Filter to 180 degrees, it will totally eliminate rolling shutter without applying the antialiasing filter if you don't want that for a particular shot.  Of course, in antialiasing mode, rolling shutter artifacts are eliminated also.

What effect does the Time Filter have on exposure?

The Time Filter reduces incoming light by about two stops, similar to a polarizing filter.  That is, if you compare a camera without the Time Filter running with a 180-degree shutter to a camera running with the Time Filter running with a 360-degree shutter (the normal configuration with the Time Filter), there will be two stops of exposure difference between those setups.

Which cameras are supported by the Tessive Time Filter?

The Tessive Time Filter has been tested with the RED ONE and EPIC, the ARRI ALEXA, Sony F3, Sony F65 and DV cameras like the Canon XLH1.  In theory, it should work with any camera capable of a 360 degree (full frame) shutter timing as well as the ability to synchronize with frame acquisition (i.e. genlock connection). It will work at frame rates up to 60 frames per second.  The filter itself is available in both 4 x 4 inch and 4 x 5.65 inch sizes (6.6 inch square coming soon!).  Contact us for more information.

A frequent follow up question is:  "Will the Time Filter work with my DSLR, like the Canon 5D Mark II, etc."  We are very sorry to say that it won't right now.  We need some sort of capability to synchronize with the camera's frame acquisition, and these cameras simply don't provide any way to do that (yet.)  We are also excited about the future of these less expensive, lightweight cameras, and would love to be able to provide a solution for them.  Our search for an answer continues.

Does this make digital footage look more like footage from a film camera?

We get this question a lot.  To understand how the Time Filter plays into this arena, we first need to understand the difference between a film camera and a digital camera with respect to frequency response. In both cases, if you have a 180-degree shutter, the exposure is a square wave of 1/48th of a second.  But in the film camera, the corners of the square wave are somewhat rounded because the mechanical shutter is a finite distance from the film, so the shadow cast by the shutter has a slight defocus.  When this defocused boundary between full exposure and no exposure passes over a point in the film, the amount of light has a slight ramp to it; it doesn't instantly change from dark to light and light to dark.  So it's mostly a square wave, with slightly rounded corners.  The digital sensor, on the other hand, has an effectively instantaneous transition from not sensing to full exposure.  Those corners of the square wave are important in determining the frequency response of the system, so the net effect of the mechanical shutter is to slightly reduce extremely high frequency response far into the aliasing band.  This will slightly soften the appearance of motion.

The Time Filter has a mathematically defined exposure curve that is changing throughout the entire time of the frame, and is engineered to give a desired frequency response.  So while it does roll off the edges, it does it in a more precise and substantial way.  The difference in response between a film camera and a digital camera is much, much less than the difference between either of them and the Time Filter.

Why hasn't someone done this before?  When you explain what it is, it seems really simple and obvious.

Sure beats us!  But nobody has.  This is actually derived from some very straightforward math, well understood and applied in many other fields.  All we can figure is that nobody ever thought of a motion picture camera like this, or if they did, they didn't make the connection.  In the defense of everyone else in the world who has ever made a movie camera, the math for this didn't really get polished up until 1949, and the technology to implement it nicely didn't exist until later.  Also, when you're immersed in a field that's been doing things the same way for years, it's hard to see that there's something wrong.