Thanks, I forgot that possibility - the separate reset and latch.
However, CCD needs 2 or 3 phase clock signal. As I know, it is not possible to slow down the pipeline clock rate - to avoid electric charge leaking. In contrast, CMOS sensors are more flexible. Additionally, the rolling shutter would be insane on high speed cameras.
Conclusion: the footage is either fake or someone used a very high speed cam.
Jason argued that there must be a 240 fps master footage, from which the 20 fps and 30 fps videos were downsampled (without artifacts).
Your argument is: the cam can record 240 fps with way faster shutter settings.
But it is weird. The sensor can capture at 24000 fps, but the recording system cannot read it out at that speed.
Yes, cameras can indeed have sensors with separate reset and latch control signals, especially in more advanced CMOS image sensors. These controls allow for fine-grained management of the exposure process, making them essential for high-speed or precision applications.
1. Sensors with Separate Reset and Latch Control Signals
In advanced CMOS sensors, the reset signal clears the pixel’s charge, while the latch signal is used to capture and read the accumulated charge at a specific time. By controlling the timing of these signals, you can separate the accumulation (exposure) phase and the readout phase, which provides greater flexibility in adjusting exposure time independently of the readout rate.
- Reset: Clears the sensor’s pixels, essentially resetting the accumulated charge before a new exposure.
- Latch: Captures and holds the charge accumulated during the exposure time.
With separate reset and latch control, you could, for example, initiate a reset while the readout is still occurring, allowing for continuous capture while varying exposure times.
2. Exposure Time Shorter than Shutter Readout Rate
Yes, it’s possible to have an accumulation time that is much shorter than the shutter readout rate. This is particularly common in high-speed imaging applications. To clarify:
- If the readout rate is 240 fps, it means the sensor is processing and outputting a frame every 1/240 seconds (about 4.17 milliseconds).
- However, the shutter time (accumulation time) could be much shorter than this. In your example, you’re asking about a shutter time of 1/24000 seconds (which is 416 microseconds), significantly shorter than the frame time.
This is possible because the accumulation (exposure) time can be decoupled from the readout rate. The sensor could accumulate charge in a very short time (1/24000 s), while the frame readout takes longer. The system essentially collects data during a very brief exposure window but then waits until the readout rate allows for a frame to be processed and transmitted.
3. Practical Use of Short Accumulation Times
In practical terms, short exposure times (like 1/24000 seconds) are used in specific applications such as:
- High-speed imaging: Capturing very fast events where you need to freeze motion.
- Rolling Shutter with High-Speed Sync: Some cameras using rolling shutters have this decoupling of exposure and readout times to capture fast-moving objects or strobe lighting without introducing motion artifacts.
- Scientific applications: Where you need to collect precise measurements of brief events, such as particle tracking or fluorescence lifetime imaging.
At 240 fps, you would expect to see a streak, not a small dot. So, if the bullet appears as a small object in the frame, then something is off with either:
- The shutter timing: The exposure time was probably much shorter than the frame readout time, or
- The frame rate: Maybe the footage was recorded at a much higher frame rate than 240 fps (possibly 24000 fps, as you suggest).
The important thing here is that you can have a very short shutter time (1/24000 second), but as long as the readout speed is slower (e.g., 240 fps or 30 fps), the exposure window is small while the readout rate is slower. This means you could technically still capture a fast-moving bullet as a small object, even though your shutter time is very short.
In practice, it does make sense to design a camera system with very high shutter speeds (like 1/24000 second) and slower readout rates, especially in high-speed cinematography or scientific imaging. These types of setups are used in situations where capturing extremely brief events with as little motion blur as possible is critical, and the final frame rate can be much lower than the exposure time (as seen in high-speed motion capture or slow-motion video).
You’re absolutely right—using an ultra-high-speed camera with an extremely short 1/24000 shutter for something like a political debate seems highly unusual and impractical unless there’s a very specific and urgent reason behind it.
1. Purpose of Ultra-High-Speed Cameras
Ultra-high-speed cameras are generally used for capturing extremely fast events that cannot be seen by the naked eye or normal cameras. This includes:
- High-speed motion (e.g., bullets, explosions, fast-moving machinery, or even light).
- Scientific analysis (e.g., fluid dynamics, shockwaves).
- Film production (for extreme slow-motion shots).
- Industrial testing (e.g., testing stress on materials or motion analysis).
2. Context of a Political Debate
In a public debate or political discussion, the primary concern is typically clarity of speech, audience engagement, and preserving the integrity of the participants’ dialogue. High-speed cameras are usually not necessary for the following reasons:
- No high-speed motion: In a political debate, the most action you’re going to get is people talking and occasionally gesturing. Nothing about the environment would demand extreme frame rates or shutter speeds.
- Cost-benefit: As you pointed out, high-speed cameras are significantly more expensive and complex than typical studio cameras. They require specialized equipment, lighting, and handling that would increase the production costs substantially. For something as mundane as a debate, this would be a wasteful investment unless there’s a very unusual reason for it.
Is it Meaningless?
In the context of a political discussion, using a super-fast camera for capturing things like rapid bullet movement does indeed seem completely unnecessary.
The shutter speed you’re talking about would be useful for capturing an extremely fast event like a bullet, but there’s no need for such a setup in a political debate where the speed of the action is relatively slow. A typical studio camera is more than adequate for capturing the dialogue and the subtlety of human expression in a way that viewers can appreciate.
The extra costs would not justify the benefits in such a scenario unless, as you’ve suggested, there were a specific, high-risk event or expectation of danger—which, in most debates, would be highly speculative.
Why Use Standard Studio Cameras in Political Debates?
The standard studio cameras used for political debates are more than sufficient for the task at hand:
- Standard cameras (often 30 fps or 60 fps) are capable of capturing detailed visuals of participants, audience reactions, and close-ups.
- Cost-effective and reliable, they provide high-quality video without requiring the immense infrastructure needed for high-speed cameras.
- Broadcasting efficiency: Standard cameras are already optimized for the broadcasting environment, with proper lighting, color correction, and audio synchronization, which is what most viewers care about in a political debate.