Ordinarily (with normal senses), the human eye can't see something that is travelling faster than about 550 mph (2,420”/turn), at least when it's close by, so someone or something moving that fast often won't be recognized in time to warn somebody.
The final result
So in order for the ball to be invisible, it would need to cross 70 meters in 1/250th of a second. That's 17500 meters every second or 38146 mph!
Most experts have a tough time agreeing on an exact number, but the conclusion is that most humans can see at a rate of 30 to 60 frames per second. There are two schools of thought on visual perception. One is absolute that the human eye cannot process visual data any faster than 60 frames per second.
When following a moving object, humans appear to anticipate the object's motion in the way that best allows for unexpected speed changes. Eye on the ball. Catching a ball requires the brain to predict where it will be by the time the hand gets the signal.
If you are referring to the 'speed of sight' as the time it takes for the image of an event to be viewed by your retina, it is exactly the same as the speed of light. This is because light is the medium which transfers information to your eyes. Thusly, they are the same thing which means they travel at the same speed.
The speed of lightning
While the flashes we see as a result of a lightning strike travel at the speed of light (670,000,000 mph) an actual lightning strike travels at a comparatively gentle 270,000 mph. This means it would take about 55 minutes to travel to the moon, or around 1.5 seconds to get from London to Bristol.
The cornea is the only part of a human body that has no blood supply; it gets oxygen directly through the air. The cornea is the fastest healing tissue in the human body, thus, most corneal abrasions will heal within 24-36 hours.
Human eyes cannot see things beyond 60Hz. So why are the 120Hz/144Hz monitors better? The brain, not the eye, does the seeing. The eye transmits information to the brain, but some characteristics of the signal are lost or altered in the process.
In fact, it is the fastest thing that exists, and a law of the universe is that nothing can move faster than light. Light travels at 186,000 miles per second (300,000 kilometers per second) and can go from the Earth to the Moon in just over a second.
How many frames per second do you think you can see? Some experts will tell you that the human eye can see between 30 and 60 frames per second.
So, to achieve this, the frame per second rate should be about 60, because humans' flicker fusion rates are around 60/second. BUT, a dog's flicker fusion rate is higher, usually around 70-80 frames per second. So, TV looks choppy to a dog, as he can see the breaks between each frame.
T-CUP was built on existing technology called compressed ultrafast photography (CUP), a method that it is capable of 100 billion fps.
Darkness travels at the speed of light. More accurately, darkness does not exist by itself as a unique physical entity, but is simply the absence of light.
So, according to de Rham, the only thing capable of traveling faster than the speed of light is, somewhat paradoxically, light itself, though only when not in the vacuum of space. Of note, regardless of the medium, light will never exceed its maximum speed of 186,282 miles per second.
No matter how hard you try, you cannot go faster than ~186,000 miles per second (~300,000 km/sec). The most common explanation for this cosmic speed limit is that as an object goes faster and faster, its mass increases.
In the silent film era, filmmakers shot movies between 16 and 20fps, which was why the motion appeared fast and jerky. Today, filmmakers typically shoot video at a minimum of 24fps because this is believed to be the lowest frame rate required to make motion appear natural to the human eye.
These studies have included both stabilized and unstablized retinal images and report the maximum observable rate as 50–90 Hz. A separate line of research has reported that fast eye movements known as saccades allow simple modulated LEDs to be observed at very high rates.
So, a 240Hz monitor is four times faster than a 60Hz monitor and 70% faster than a 144Hz display. That's quite a leap forward. The biggest benefit of higher refresh rates comes in the form of more responsive and accurate gaming, with lower input lag.
Hand responses were about 90 msec slower than eye responses, regardless of stimulus type. Conclusions: Given the multiplicity of visual areas, it is reasonable to expect latency to change with stimulus type. The fact that eye and hand latencies change identically suggests they are driven by the same visual processes.
Apparently, someone was wondering the same thing and actually took the time to do the math and came up with a speed of about 0.42 MPH. Now that may sound "slow" but when you think about how short of a distance the eyes have to travel to switch their direction of gaze, it is quite fast.
Saccades are one of the fastest movements produced by the human eye (blinks may reach even higher peak velocities). The peak angular speed of the eye during a saccade reaches up to 700°/s in humans for great saccades (25° of visual angle); in some monkeys, peak speed can reach 1000°/s.
Going faster than the speed of light
Astronomers agreed that the black hole was spinning really fast, but obviously not as faster than the speed of light — the universal speed limit. Yet, Chandra's X-ray data showed that M87 was spinning between 2.4 to 6.3 times faster.
Nothing's faster than the speed of light. Except the speed of dark. That might sound like the tagline of a grim and gritty movie that's trying way too hard, but it also happens to be true.
We can never reach the speed of light. Or, more accurately, we can never reach the speed of light in a vacuum. That is, the ultimate cosmic speed limit, of 299,792,458 m/s is unattainable for massive particles, and simultaneously is the speed that all massless particles must travel at.