If there is one thing that's always classy,
whether in cinema or research, it has to be slow-motion.
So today our Science 2.0 will become a bit more technical
and we'll take a look deep into how high-speed cameras work.
In order to understand, we need to start on a good basis.
A video, whether it be a movie or the one you're currently watching,
is simply a sequence of still images.
In this case, this one is at 25 frames per second (fps), the PAL standard.
So the camera that's filming me right now captures 25 frames in 1 second,
and what you see is just the sequence of those images, put end to end.
A high speed camera will actually take many more frames per second.
And even if it seems counter-intuitive, you'll see that it's actually very logical.
Let's take an example with this sequence.
If you want to slow it down, you need to decrease the playback rate,
but it quickly becomes jerky and you don't see much more information.
Now, assume this camera is running at a speed of 2500fps.
In the amount of time a normal camera would take only a single new frame,
this one has time to capture 100.
So if you slow this new video down to 25fps,
the result with still be smooth and now you can see all the details of the action.
Now that we understand the principle, we need to try it out,
but there are still a lot of things to know about high speed cameras.
So, first thing that is super important to know,
a high-speed camera absolutely doesn't run like a regular one where you just hit record and then stop.
It runs with a Buffer, which is basically RAM memory,
that will be filled little by little by frames recorded permanently,
and when you trigger the camera, it only records - say 8, or a couple seconds before you pushed.
Yes, it only records for a few seconds, because generally,
2 or 3 seconds of video equals several tens of gigs of files, really.
So without further adieu, a little demonstration with a water balloon, classic.
So now I'm going to start recording...
Now the Chronos is constantly saving new frames and erasing the past, so when I pop the balloon...
I have 8 seconds to trigger the camera, or the images will shift into the memory and disappear.
This is why you often see people run to stop the camera.
Let's see what it looks like.
Right now the video's only in RAM preview, so it's not properly saved.
Here we have the whole video, and as you can se we can scroll
up to the moment, here, where it bursts.
Usually what we do is set an in-point to the video, and a little further an out-point,
and we'll save only this portion, which makes our final video.
Oh yeah..! That's so awesome!
Every high speed operator's worst nightmare.
Light.
These cameras need a ton, there's never too much light when filming in high speed.
And it's even worse when you increase the frame-rate, inevitably.
When you shoot, there's whats called Shutter speed,
it is basically the amount of time during which light can hit the sensor
and thus the image is taken.
When shooting at 25fps, you can set a maximum shutter speed of 1/25s,
because then the next frame comes.
So when you shoot at 10,000fps...
You can't go higher than 1/10,000th of a second, so that lets even less light in. And still!
Shutter speed is usually set as low as possible
to get images as sharp as possible, otherwise you'll end up with motion blur.
Picture yourself the capture of a frame as a disk with a spinning bar.
When they say that the shutter is set to "360°"
it means that light is capture during the full cycle of each frame.
Usually on TV / documentaries, it's set to 180° which is half the frame interval.
But it you want to capture projectiles, explosions or stuff like that,
you need to go down to 30° or even lower.
So imagine shooting at 10,000fps and capturing light during...
a tenth of a 1/10,000th of a second.
Yeah right, you need 3 suns, 2 spotlights and 4 reflectors.
But this light doesn't only need to be powerful,
it overall needs to be continuous.
Because household electrical current is alternative, so if you use regular neon lights,
you will see them flicker at 50 or 60Hz - impossible.
To remedy that, you need to either use LED lights that use DC current,
or big spotlights called HMIs, with a ballast that will provide flicker-free lighting.
Friends, I'm sorry I have to crush your dreams. A high speed camera...
Never captures sound.
TAM. TAM. TAAAAAAAAAAAAAM!
Never.
It never records sound.
I'm gonna show you something.
This is a big microphone. This is a big glass blottle.
I'm going to smash it, film at 3,200fps
and slow sound down the sound just as much as the video, you'll see how absurd it is.
Smashing a bottle and recording sound in slow-motion...Go.
It messed up, I'll do another one.
And triggered!
Now, admire.
So next time that you think the sound is great, think of the hours spent on editing.
And brooming.
So I believe we get it now, that high speed is cool but also very capricious.
So what makes a high speed camera more powerful than another?
To compare them, there's a unit called the gigapixel per second (Gpx/s).
It is basically the number of billions of pixels the camera is capable of saving in one second.
In this case, the Chronos 1.4 captures 1.4 billion per second,
to compare, my friend Stéphane's Phantom is capable of shooting 3.2Gpx/s -
[Stéphane] Eeeh turn on your brain!
- and the most powerful of all... This one...
Runs at 25Gpx/s. There you go.
Some day, some day...
And this number of pixels per second is set in the camera and constant no matter the settings.
That means if you want to double the frame-rate you capture,
you also need to split in half the amount of pixels in each frame.
For instance, say you can capture 1000 x 500 at 5,000fps
if you want to shoot at 10,000fps, you need to crop down to 1000 x 250.
We always hear about Phantom but tons of other models exist;
Olympus makes high-speed cameras, Fastec, Photron...
And the Chronos 1.4, which has the advantage of being affordable.
A Phantom like the one my friend Stéphane has costs €70,000, yes it does.
And the biggest Phantom I was talking about?
Oh, betweet €180k and €220k...
Well that's cool and all but this video needs one more thing... Some slow-mo!
Alright, here's a little compilation of what I got to shoot with this camera,
and everything you've seen in slow-motion on my channel.
[Stéphane] Ok now I'm taking 20 years...
[Laughter]
[Baptiste] Look at your face!
[Stéphane] You've got the cheeks... I think your cheeks drop a lot.
[Laughter]
[Baptiste] Oh my, look at that little smile!
This is the last thing I'll see, I'll see the light!
[Laughter]
I can't feel my toes!
Thank you everybody for watching this high-speed special Science 2.0 !
Big thanks to David Kronstein for lending me this camera,
which doesn't even exist yet but really impressive.
Don't forget to Like, subscribe and Share the video if you enjoyed it!
Thanks.
Merry Science to you!
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