Slow Motion Film and High Speed Photography

how today's podcast really lends itself to that quote. Yes, today we wanted to talk about high speed photography and slow motion. Both of these have to do with a changing film speeds and shutter speeds and all this kind of stuff. To really talk about how the stuff works, we have to go a little bit more basic. We have to actually talk about the principles behind photography and

how a camera works. And before we really get into this, How stuff Works has dozens of great articles about photography, including articles about how high speed photography works and how burst photography works. Both of those were written by John Fuller. But we also have how cameras work, how photographic film works. So if you want to learn more than what you know,

we're going to kind of cover the basics. But if you really want to know the true science and chemistry and physics behind how cameras work, I highly recommend you check out those articles because they will answer a lot more questions. We're gonna try and kind of cover the basics here. So so let's uh, let's talk about what a camera does. It's seemed kind of silly to say because we're most of us really familiar with cameras. And by the way, I should point out also that we're

really focusing on film phil it was completely not on purpose. Um, we're talking about film cameras mainly in this podcast as opposed to digital. The two different methods. You know, you get the you get a result that's similar using these two methods. You know, you get an image of a moment in time in both ways, but the actual mechanics

behind film versus digital are very different. So we're specifically looking at it's gonna say, focus again looking at film cameras because well, to to to try and cover both would require a like a podcast that's twice as long as what we normally do, and we only do that for Google Plus well, UH cameras in general though, UM and speaking of both film and digital, you're you're you're using a series of UM devices to capture that image. There.

On both film and digital you of course you've got a lens um and there is UH, the principle behind it is to capture the image. On film, you're using a a piece of essentially plastic celluloid to that's treated with chemicals they captures that image, and in a digital camera use an image sensor. UM. But you know, and and there are some similarities of course. It It has to do with how fast the camera is firing UM and how much light you're letting in through the lens

um and after that they do differ considerably. So with a with a film camera, you know, Chris was just talking about it a second ago. But what you know, the main the medium upon which you are capturing these images is film, and film is really just a strip of plastic that's been treated with UH, with chemicals that are photoreactive. Yes, that means that the chemicals will undergo some sort of change when exposed to light, so they

turned into monsters. If you've listened to our solar If you listen to our Solar Panel episode, you know that we have discovered materials that react when light hits it. The photons from the light transfer energy to whatever that medium is and you get a reaction. In this case, the photons are able to change the chemical properties of the stuff that's on this film. And I really get into that would be diving deep into science. We do have, like I said, the article on how photo, how film

photographic film works, and that explains it. But UM, to be honest, if I were to try and go into it right now, I'm sure I would mess it up because you know, my my chemistry is only goes so far. My chemistry food is weak chem But at any rate, what this this stuff is designed so that when light hits it, it has a chemical change. Then when you treat it with other chemicals, that's what allows you to create a negative image of whatever it was you were,

whatever light hit it. So this is why when you have film, people say, you know, make sure you don't expose it to light before before or after you take a photo, because if you do, it's going to ruin the image, right because um, the film is going to record the light from the that that is coming to it through the lens. So of course, when you put the canister a film inside your camera and load your camera,

you close the door which blocks off any light. Um. And then of course you have to advance the film after you've taken a photo. If you if you've ever exposed film more than once, double exposure, you get a really bizarre effect. Yeah. Yeah, And it can be very very cool if that's what you're going for. It can also be really frustrating if you were trying to capture one thing in particular and forgot to advance the film, right.

And and we've even seen that double exposures go into uh the realm of people thinking that something supernatural roles going on, because you do get kind of a ghostly

image if you double exposed film. Yeah. So there have been times where people have had just a double exposure, that's all it is, but because they didn't realize it was a double exposure, they think, Wow, I took this photo of my buddy Bob, and there's this ghostly face that's appearing over his left shoulder that's so creepy, and not forgetting that, oh before I took the photo of Bob I took a photo of Liz. It's just that Bob's photo was exposed over Liz's photo, and now Liz

looks like she's a ghost. Actually, I thought it was because Bob worked at that leaky nuclear plants. Because we took all those photos over that Indian burial ground. That was a mistake we made anyway. Um uh. The the the idea here is that the camera gives you a very controlled way to expose that film to light. And the way this works is that first you've got the lens, and the lens is purpose is to direct light to the film, So the lens is allowing light to pass through.

When light passes through a lens, that actually the speed of the light changes. You know, speed of light is a constant, but it's a constant that's based upon whatever the medium it is that it's traveling through. For example, air, Yeah, air, it's going to travel through it. Light travels through air much more quickly than it will a lens. And the curvature of the lens, the thickness of the lens, that's all going to make the light travel at at slightly

different speeds. The point being that you focus all that this light onto a point so that it exposes just the right spot on the film. Now, behind that, you've also got a device called the aperture. Now the aperture is essentially a hole. It's a it's it's a disk that can expand or contract and allow more or less light to pass through the from the lens to the film. So it's it's a barrier between the lens and the film.

And you adjust this in order to uh to really kind of tweak your photo settings, like with a with a manual camera, a manual single lens reflex camera or SLR manual SLR uh by the way, in case you're curious, for those of you who are only familiar with digital cameras, a manual single lens reflex camera is not electric at all.

It's it uses chemicals and it uses mechanical little gears and things, but there's there are no electric components necessarily in a true manual single lens reflex or at least you don't have to have any electronic I think that's so in other words, it's kind of interesting because we

we take it for granted now with digital cameras. Right, digital cameras, you have lots of electronic components, but with a a an old manual single lens reflex, you're just you're just turning little dials, which is advancing the film. You might turn a little crank to rewind film, but there's nothing necessarily electronic in it. Um. Of course, there are hybrids that as well, But anyway, this the aperture helps you determine how much light can enter through the lens.

And then you have something else called the shutter, and the shutter determines how long the film is exposed to that light. So if you were to take a photograph with a shutter speed that is a you know, it allows the shutter to be open longer, then your photo is going to be a little more blurry, unless the

subject of your photo is incredibly still. So if the camera is still and the subject is still, and you've got a decent amount of lighting, and the shutter is open longer, theoretically, as long as as long as the light's not too great, you will actually get a very clear image because it's it's really capturing that uh, that moment um. Now, if something is moving, then you're gonna

get a blur. So if you've ever looked at some nighttime photography especially or like city scapes where you can see where traffic is moving through and it's like beautiful red streaks on one side of the road and white streaks on the other that you know, that's obviously the traffic where cars are coming and going. That's usually using a camera with a shutter speed where the shutters remaining

open longer. Sometimes it can be as long as you know, minutes or or more, and that creates that streaking effect because all that light is hitting the camera over an extended time, so instead of seeing individual cars, you're seeing these streaks. Yeah, this this has basically it's a combination of things. It's a combination of the aperture setting that you're using to expose the film, uh, the shutter speed, and there are cameras that you can manually hold the

shutter open uh as long as you want to. It's often better and creating the photos like Jonathan was just talking about, where you leave it open for minutes to have your camera on a tripod and use a cable release, you know, just so that you don't nudge the camera because otherwise you're going to uh jar the picture and distort things. So yeah, it also has to do with the speed of the film. And uh, it's funny because that's sort of a misnomer. You know, there aren't little

canisters of film moving faster than others. It has to do with the chemical properties actually the film. UM. And again we're not going to get into the chemistry behind it so much. UM. But uh, you know, depending on the speed of the film, you would be able to capture uh photos in darker environments or lighter environments. UM. Also, the speed of the film has is depending on on

this the type of photography you're doing. If you're trying to capture high or fast motion photography, you're gonna want something that you can expose um to light more frequently, like a higher speed film. UM. You know, you want something that's going to to just from a very brief exposure be able to capture an image. And and by exposure,

we're talking about exposing to light. You know, just keep that in mind that that exposure has everything to do with the amount of light and the duration of light that hits that film. So a high speed film can capture an image with light hitting it for a shorter time frame. And we're talking fractions of a second. Here, you know, when we talk about a short time frame,

we're talking really short. We're not talking like, oh, well, you know a woman thousand two one, now you would be able to take hundreds of photos in the mount of time. It took me to say that depending on the speed of the film and the shutter speed and all of this kind of stuff. So so high speed

photography kind of leads us into this. High speed photography is all about trying to capture, uh an image of something that's moving at an incredible speed, something that that is moving so fast that to the naked eye it may be either a blur or perhaps even you know, practically invisible because it's going so quickly. But you want to be able to capture that moment in time so that you can see a very distinct image. Well, this

is a challenge. You have to figure out how are you going to do that, and a couple of different ways. Perhaps I hesitate to say the easiest way, but perhaps the simplest way is to set up your camera in a perfectly dark room and you just leave the shutter open. Because remember, even though the shutters open that film, if there's no light, the film is not being exposed. So you've got this film that's just sitting there. Nothing's happening to it. It's not reacting chemically at all because there's

no light coming into the camera. You set up whatever the thing is you want to take a photo of, and then you have it timed out so that the instant that thing happens, there is a flash of light that is up and down in a fraction of us can and just that fraction of a second is going to be long enough for the light to go through the camera and uh and to expose the film. Then

you could advance the frame and do it again. Now, this is a very slow, painstaking process, and it requires an incredible amount of timing, and there are a lot of different ways of setting up a shot so that the uh, the the light will trigger at the right moment. Some of them are acoustically triggered so that there's a noise and that noise causes the light to flash, which

automatically exposes the film in the camera. You don't have to do anything to the camera at that point, right, You're not pushing a button because the camera shutter is already open. It's only after the light is flashed that you have to advance the film so that you can take another photo. Otherwise you're going to have a double exposure, high speed double exposure on this this film, which I think would look really weird. Um. So that's one way

you can do it. But of course, if you want to take a high speed photo of something nature, for example, the the an example that a lot of people use as a hummingbird, because a hummingbird can beat its wings so quickly that with most cameras, if you took a picture of a hummingbird with a standard camera, it's gonna look like a bird with two blurs next to it, right,

you won't be able to see the wings. Um. But if you use a high speed camera where it's able to move the shutter at a really fast rate, and you have a pretty well lit environment, then you might be able to capture an image of a hummingbird where you've got its wings perhaps in the upper down position, and you can get a really clear look at that bird.

But it does require that you have a camera that can move that shutter speed at a really really fast rate, and that you have a high speed film that's capable of taking light for a incredibly brief exposure time and convert that into an image. Yeah. You know, UM, if you're a text a listener normally UM that we like to get into the history of things. And I wouldn't necessarily have have thought of high speed photography is I would have thought it was a more modern UM, something

that was more modern phenomenon. But really the history of high speed photography goes back just about as long as the history of photography itself. UM. The first example that I I read about UM from a a uh AN article by Lincoln l Endelman, which was William Henry Fox Talbot's uh trial where he basically exposed a piece of the London Times newspaper that was on a wheel that he attached it to, and he was using a wet plate camera, which is basically a piece of glass that's

treated with chemicals rather than a film camera. Interesting. I had never heard of that before there was one, and heard of the camera obscura, which, by the way, you can actually build one of those yourself if you or wanted to, But I've never heard of the wet plate camera. That's interesting. He uh and for a flash he was using laden jars elimination from laden jars. This is like the coolest camera ever. Yes, and cumbersome because you know, you don't really take this thing out to go take

shots at the family on vacation. I'm out to the high school football game. Let me carry my laden jars and wet played caral with me. But but I need the team's help setting this up. But he didn't manage to get a readable photo of the newspaper at the shutter speed of one of second unexposure speed. Let's say that actually used. But you also probably remember Edward Mindbridge. I remember the name. Yes, yes, he had a famous experiment where um, he had set up a series of

cameras too, because there was a challenge. Um, you may have heard of this guy, uh um Laden, I'm sorry, yeah, I'm sorry. He may have heard of this guy at Leland Stanford. He was the governor of California and he was that that was the challenge was does a horse pick up all four of its feet when it's running?

And he was the one my bridge and a lot of people have seen this, uh seen this series of photos where they proved that the horse was picking up all four of its feet because he had a series of cameras and that the horse was tripping it as it ran by, and so each camera took photos a different a different way of doing it, but they captured a series of still photos because as the horse was running by, it took you know, each camera in turn took a still photo, and when you put them all together,

you get essentially slow motion of this horse running. Yeah, and yes it does pick up all of its feet when we'll get it, and we'll get into that in a little bit, because of course the photography does lead into cinematography. But before we do, I, before we jump into that, I just wanted to mention one other kind because I did mention burst photography when we were for introducing this podcast, and that that John Fuller, Editor Extraordinaire

UH wrote the article on how burst photography works. First, photography works on a similar principle of high speed photography. Now, with high speed photography, you may be talking about taking a single image and then setting up and taking another single image, right right, That's like I'm pointing, I'm pointing my camera at a hummingbird and I take one photo. Right. The point of the high speed photography here is to capture a very accurate still. Yeah, yeah, something that's going

to be. It's really used a lot in things like sports, you know, trying to catchure, capture that dramatic moment where the quarterback is releasing the hail Mary pass. I'm saying that right, right, because I don't know anything about football or you know, the people who absolutely positively have to have that shot of the water balloon after the balloon is broken and the water is still in the balloon shape,

but for the apple with the bullet through it. But clearly this sort of that has to happen, this sort of this sort of event is of course really hard to capture on film, not just because of the nature of the mechanics where you know, you've got to have a camera with that proper shutter speed and film with that proper um photochemical reaction speed. You also have to have insane timing, and even by setting up an automated system where everything's going to happen automatically, you know, as

soon as the event happens, it triggers the camera. Even that is really difficult to do. So perhaps what if you could have a camera that could shoot a series of photos in a very short amount of time using that same kind of principle. Well, that's what burst photography is all about. These are cameras that have not just the really fast shutter speed and not just the special film that's going to to react quickly to a very brief exposure, but also the ability to advance film rapidly

as you're taking photos. So with a burst photography camera, it's pulling the film through very quickly and the shutter is opening and closing, causing multiple exposures, but you're not not a double exposure because you're you know, the films being pulled through as you're as you're doing this so that you can take a series of photos in a brief amount of time, so like in a second or two,

you might take dozens or more photos. And this way, Uh, the nice thing about this is that you can point your camera at whatever the event is and just start shooting photos until you're out of film and you have a better chance of capturing that iconic moment you're after as a photographer. Yeah, this is uh, this is one of those times if if you haven't really done a lot of work with people who are professional photographers, and you might be going Last time I bought film, I

only had twenty four exposures on a roll. You can buy, you know, if if you are interested in doing this, Uh, you can buy whole magazines of film and you know, attach them to the back of your camera where you have a very very long roll. Or you can of course make your own, uh, if you're so inclined and

are good in the dark. I used to have to actually I was a newspaper report for a couple of years, and um, you know, we'd have a big roll of film and we'd load the magazines are are the cartridges ourselves. And after a while you get pretty practiced at it. But the first few times, uh, I wasted some film. Um, but yeah, I mean so so this is sort of one of those times when digital cameras sort of have an advantage because now that we have bigger memory cards

and better digital photography. Um, the digital cameras are are so much easier and more cost effective uh than than film cameras in this regard. But the burst photography is amazing, especially if you are you know, it allows you to set up and have a much better shot at getting your shot than than just just clicking and hoping that you got it. Yeah. Yeah, Well this kind of leads us, like I said, into cinematography, using film to capture images in motion where you are going to play it back

so that you have the illusion of motions. So remember film as in like I'm going to the movies to watch a film is the the illusion of movement. And it works because we capture lots of images and then we put them in order and we, uh, we expose our eyeballs to those images very in rapid succession, and that creates the illusion of movement. So uh, the typical film projector will play back film at a rate of around twenty four frames per second, which means that every

second that passes, you're looking at twenty four images. Twenty four photographs essentially, is what that is. So you're looking at twenty four photographs in a row per second. Because of that, it sort of gives this, It gives this the illusion of the things that you're looking at are really moving. It's not that you're looking at instances that are put together. It's like it feels like a flowing

motion that has no no real interruption to it. I think it's interesting to note too that when you're you're saying twenty four frames per second. That's each frame is a second. That seems pretty fast. But in my research on high speed photography, I saw mentions of one eight of a second. Um. Of course that would take a whole lot of film. Yeah, but you know, it's it's interesting to note that a second is reasonable enough to give us an idea of motion and to create that

illusion for us. So, if you have a projector that's going to play film back at a steady rate, so let's let's go with the twenty four frames per second. But you have a camera that can take that can actually exp those film at a variable rate. That's where you can start playing with the slow motion or fast

sped up motion on films. So if you've ever watched an old movie where for comic effect, usually characters start moving around really really quickly, you know, like there's a chase scene and suddenly everyone's running at a speed that doesn't really look natural. Yankety sacks may very well be playing they did, and that's none of that, um, before I get sued and uh, anyway, yeah, so this this is playing with taking more images per second and then playing it back at a steady speed. Um. Now, in

the old days, the good old days of filmmaking. Those days you had cameras that were hand cranked, which meant that you had a camera man or camera woman really camera person um turning a crank that was squirrels possibly turning a crank and hopefully a fairly consistent speed for normal filming to advance the film through the camera as

it's being exposed to light. And the idea of being that you want to turn the camera at a good rate so that when you're projecting it back through the projector it's a steady, smooth experience right when you are dB. So yeah, so this this camera is not automated, it's it's it's manpowered, and people are known to be you know, imperfect. Yeah,

not terribly consistent sometimes. Um so, yeah, if you turn the crank faster than normal, you'd be exposing more film in the same amount of time than you would if you were going at your normal rate, which and when you're playing it back, remember you're playing it back at

a h at a fixed rate. So if you've captured more images in that amount of time then normal, then you get the effect of slow motion, right because while you've while you've captured maybe say, uh, you know, forty eight images and then uh, you know, so you're looking at forty eight images over the space of a of two seconds. Uh. If it were played back at normal speed, now you're looking at it at one second while everything starts to slow down. That could be distracting. Yeah, so

this is a that's over cranking. Yes, it's when you're cranking the camera faster than the projection playback speed. And there's also under cranking, where you turn the crank slower than the projection speed. This causes a sort of the herky jerky fast motion stuff that you see, especially in older films, where people start to are moving faster than they normally could, and often it looks a little jumpy

because you're missing information. Right, the the the more amount of time you have between when two images are taken for something that's in motion, the less natural it's going

to look when when you're playing it back. Right. Because so if I took a picture of Chris right now, and then three seconds later took another picture, and three seconds later took another picture, until I had, you know, two photos, and I played them back at an at a regular speed, uh, where it would look really really jerky, you know, it wouldn't look natural at all and jerky, not just because of the subject matter, but bump bump. So it's only because I've been dried and cured. Right.

So you may have heard of the term of speed ramping. Speed ramping is when you in the good old days, it was done by accident, but today we do it on purpose. Speed ramping is when you change the capture rate of uh the film or video during a shoot, and this is where you get those weird effects where

like it's often done in action sequences. For example, let's say it's a fist fight between two characters and it starts out normal, and one character starts to throw a punch, and just as the characters throwing a punch, it switches so it goes into slow motion, and then just as the punch makes contact with the other person, it speeds up again and it changes, uh the the capture rate, but the playback rate remains constant. That's what we call

speed ramping. And there's certain directors who are infamous for speed ramping. Um just you know, if you ever have seen the movie three hundred or Watchmen, you know one of the ones I'm talking about use a speed ramping so much that it's distracting at times for some people. Other people love it. I I personally think a little

goes a long way. I'm sorry anyway, that they're all based on the same principle, the fact that if you keep the playback rate steady and you change the capture rate, you can you can make film appear to move slower or faster. Um. Now, you could also play with the playback rate. If you kept the capture rate the same and you change the playback you would get the same effect, right you would. You would either try and display more images per second or fewer images per second than normal,

and you could get the same. Fact. This is a lot easier to do in video than it isn't film. Sure, sure, but it's funny to note again that like so many other things in photography, that the key to slow motion is high speed photography. Um. To to really get an idea of what's happening and slow it down, you have to capture many images so that you can you can go from image to image at a slower rate and really get a good idea of of the motion and

how things are transpiring. Uh in that image. Yeah, yeah, if you if you take an uh a video of something or a film of something, and it's at eight thousand frames per second, and you play it back on a twenty four frames per second projector, it's going to take you a long time to get through. Like even if you only shot for maybe five seconds, you know that's gonna take you a long time to get through those five seconds when you're playing it back at a

rate of twenty four frames per seconds. So then you get this incredible slow motion effect where at times it may look like nothing is even moving because everything is. You know, you're capturing such tiny moments of time that it's hard for us to detect changes until they are

dramatic changes. And this is where you can't. You can see some of those really cool effects where like Chris was saying, the water balloon, where you pop the balloon and the water has retained the balloon shape for a couple of a couple of split seconds, like moments in time, and then you start to see it. You know, of course, fall uh that that's we've seen some really cool footage because of the this uh this technique, and you can too if you go to the house stuff works dot

com site. We have a lot of clips from the Discovery show Time warp Um, which was really popular a couple of years ago because it showed extreme slow motion. Yeah, using amazing high definition slow motion cameras that are taking thousands of frames of footage per second and then playing it back at normal speed. Yeah, and it's just it's absolutely amazing. I can. I can watch them all the time, you know, even the ones I've seen before, you know, I can. I can go back and watch it just

because it's so fascinating how how all that works. I love the ones where people get slapped and you just see the face deform slowly. Wow, that's what happens. Whenever I say anything to anyone that's insane. I'm I'm constantly can't. Yeah, my face is hurting. I got slapped just before this podcast. Actually yeah, but it was you that did it anyhow. I never said that it was necessarily caused by someone else. That's true, that's true. But yeah, I mean you can

you can. You can see at right now. They're they're still up there. And I think when we post this will probably I'm pretty sure there's a playlist we can we can show people. Yeah. Um, yeah, that just it's just a lot of fun to do that. And it's a lot of fun to to fool around with high speed photography just as that, you know, just as somebody who is a hobbyist, um, to see what you can do with it. And now, granted, if you want to get like a really good high speed camera, this can

be an expensive hobby. Yeah. I mean, if you're talking about the top of the line uh kind of set up, then you're you're looking at thousands of dollars. So it's not a cheap hobby necessarily, but it does really it's really cool now and then you know, if you're if you're really staging things too, um, yeah, of course, then

you have got the whole staging costs and stuff. Yeah, and you're starting to talk about again because it is a matter of uh, the camera detecting the image and and getting synchronized with the the event that you're trying to photograph, and um, you know you have to buy the equipment to do that. We were talking about sound equipment. They are setups that require you know that that the sound will true cause the the camera to fire. And

you know this is again you're having to buy more gear. Um. But it's it's it's fun if you can afford it. It's pretty pretty interesting stuff. So yeah, this wraps up at our discussion about high speed photography, slow motion cameras in general film. Uh stuff is really really interesting. In fact, it's so interesting to me that when I look at

the complexity of these devices. I mean, the principle is pretty simple from a high concept point of view, but when I start looking at the ingenuity that was required to bring a camera into reality, Uh, I just it's phenomenal to me. Again, It's one of those things where we take it for granted now because they're everywhere. I mean, we have cameras incorporated into practically every mobile device you can think of, but the principles behind it, and it's

just it's just phenomenal, amazing that we figured us out. Yeah, I mean think about we I mean, people way smarter than I am. Well, you think about how the difference in the early cameras that you know, degaro types and and the wet plate type devices versus the tiny little cameras in our smartphones, you know, shoes and everything else. I don't want any shoe cameras. Let's let's not do that. Okay, alright, alright, shoot people out there, don't put cameras in your shoes.

How about diamonds on the soldier shoes? How about self lacing shoes? Hey, they just came out with those. Yeah, well all right. Anyway, we're gonna wrap this up. So guys, if you have any topics you would like us to talk about, please let us know. You can let us know through email. Our address is tech stuff at how stuff Works dot com, or you can drop us a line on Facebook or Twitter. Our handle there is text stuffed H s W. Chris and I will talk to you again really soon. Be sure to check out our

new video PI cast Stuff from the Future. Join how Stuff Work staff as we explore the most promising and perplexing possibilities of tomorrow. The House Stuff Works iPhone app has arrived. Download it today on iTunes, brought to you by the reinvented two thousand twelve camera. It's ready, are you