 So, have you ever wondered what the big deal is with ISO? Photographers are always talking about it, and people are always talking about the ISO that they took a picture at, or when you're in an art gallery looking at photography, you might be seeing little notes underneath the photographs that sometimes say a speed, like 100 or 200. Sometimes you'll see 400 or 800, and even very rarely, you'll see numbers like 1600 or maybe even 3,200. A lot of advertisers or a lot of companies are advertising these higher speeds as well on cameras these days. And a lot of times you kind of look at that and think, okay, well, what does that mean? Well, it means a lot, actually. It means a lot to the quality of the photographs that you're taking, and it means a lot in the functionality of the camera. ISO is basically just the ability of film to take a photograph at a higher speed. So the higher the number, the faster the film, the faster it will be able to take a photograph. And this is just important when you're trying to capture action or motion and have higher shutter speeds so that your images aren't blurred. So, you know, if you have someone moving through an image and they're running or something like that, you want to have a higher shutter speed. That means you want to have a faster film, possibly, maybe depending on the light that you have. But let's talk a little bit in very general terms about what this means and why this is the way it is, why this works the way it does. And we're going to start by having two roles of film. We're going to have our slow film up top, and we're going to have our fast film down here at the bottom. So let's start with maybe a 100-speed film here. And down here we're going to have a 1600-speed film. And so for those of you who are digital shooters and have grown up in the time when film was not something that you've ever used, this might seem a little bit odd, but I'm going to start by explaining it how it worked back in the film days because it basically works the same now, and it is really important to kind of understand where this comes from and how this works. Now, old film basically used something called silver halide. And this was basically little flakes or is. I mean, I still use film, so I shouldn't speak of it as if it was not around anymore. But it used little tiny flecks of silver halide that would capture the light. So the light comes into the lens, into the camera box. And it is captured then on little tiny dots that are picking up that light. And you can see here I'm trying different colors. So we'll imagine that this is color film. And these tiny little points of silver halide are picking up the light and saying, oh, I see blue, or I see green, or I see purple, or whatever, seeing lots of different things. And when you had a lower-speed film, these pieces of silver halide were really small. Now, as you kind of move down the scales, as it gets darker, you need more light sensitivity. You need more light to hit the film in order for the photo to be useful. So you don't want a black photo, so you want to have the film be more sensitive to light. And to do that, you can do a lot of things. You can slow down your camera, so you open up the aperture and let more light into the box, into the camera, onto the film. And so you can have a faster lens and you can have a longer shutter speed, but sometimes you just need faster film because there's basically just three variables to all photography, your ISO, your shutter speed, and your aperture. Well, in order to achieve these higher speeds, they just kind of made the pieces of silver halide like a little bigger and a little bit more sensitive. You know, just use some different technology to make it work that way. So instead of having little tiny points, you had these kind of bigger points. And so they weren't so big that you couldn't, you know, that you couldn't see detail, but they were just big enough that you actually started to really notice like, oh, I see little flecks on this photograph. It kind of looks like it's covered in flakes. And those flakes are the silver halide that are just kind of working really hard to capture that light. So this was really common, basically. I mean, sort of starting around 800, but really sort of in the 16 pluses when you started to see really sort of what they called grain. This is called grain. I'll show you what grain looks like a little bit later. But that is how it worked back in the film days. And now let's take a look at how it works in the digital age. So now you have a digital sensor. It looks something like this in the back of your camera and your lens is maybe up here somewhere. And you've got this little cube and it's attached to a battery here. And we'll put little terminals on the battery. And your images are basically just made by light coming flying in. We'll put a couple of different types of light coming in, maybe some red light coming in and some yellow light coming in. So all this light is coming in and it's falling on this light sensitive sensor. And the sensor is basically the opposite of a screen on a camera or on a, sorry, on a computer or something like that. It's little points, little pixels that are sensitive to light. And instead of kicking out the light, you know, so you're seeing it's instead of like projecting it, it's accepting it, it's sort of sucking it in and turning it into a file and then sending it off to your SD card to say, oh, here's a picture of my dog. And all of this is created by sending electricity through this sensor. So the sensor is getting some electricity. And the electricity is set at a certain amount for each ISO. So most sensors have a default ISO of around 200, something like that. So they say, okay, this is the amount of electricity that we send through. And each sensor is designed to be about ISO 200. That's where they're built to be about as sensitive as ISO 200. But if you want to move up and say you want to, I don't know, maybe you want 400. ISO 400 has another speed. So they add a little bit more juice to it to make it 400. So if they add the 200 speed and then they add a little bit more electricity and what the resulting file is then ISO 200. And maybe you have want ISO 800 and that sends a lot more energy in and sees something of, oh, okay, that's an 800 ISO image and the information comes out. So it's basically an analog digital surface that you're just pumping more electricity into it, gives you a higher ISO. And so the higher they get, though, the more the quality sinks because it works just the same way the silver hallowed work where you have bigger pieces of the sensor, sensitive area are working to expose that image. So instead of having a little tiny point, it's like a bigger point. And in principle, that's how it works. It's a little bit more complicated than that, obviously, but that's kind of the basics of it. So let's take a look at what this means for your images. I took these two photographs at two different speeds. This one here is at 200 and this one here is at 3,200. This is taken with an older camera that I used to use. And you can see just from this image, and I'm not sure if you can see this on YouTube, especially if you're watching this really small, but there's a pretty major difference here in the black right here. The quality of this black is very different. You can see it kind of looks speckled over here and over here it doesn't. You'll also notice here, especially important, the orange in the little eyes of our little, these are our robot pepper and salt shakers at my apartment, by the way. You can see that the contrast is a little different. So you can see that the colors aren't as vibrant in the higher ISO image and this is really common. So you have a decrease in quality with high ISO and you have sort of a drop in the color tonality and things like that. And some more important stuff, which I'll show you here in this little zoomed in version. You can see we've zoomed in on the pepper shaker here. And we'll call him Zolaar, the pepper shaker. And you can see here on his Zolaar's chest here, this is what it looks like here on the left, the 200, is what it really looks like. It's just a piece of black plastic, you know, so it's one color. But if you look at it on the 1600 or sorry, the 3200, I keep making this mistake, the 3200, you can see that it's like little flecks of blue and red and sort of, it just kind of looks a lot different. The quality isn't the same and it's not as good. And so you can see that everywhere though too. It's not just there, it's, you can see here and you can see it here and you can see it, especially in the orange, the color of the orange. And this is just basically the little pixels in the camera freaking out going like, where, what light am I seeing? I'm not sure and I'm being overwhelmed by electricity. Oh my God. So when you take an even closer look, you can really see how this works. And I think this is probably one of my favorite slides in the whole lesson. You can see how ISO works actually, just by looking at the image. You can see here that each individual pixel is saying, I see gray or I see brown or I see brown-yellow or I see black or sort of red-black. You can see what each pixel is saying. But if you look over here, you can see, like this pixel is like, hey I'm not sure what I'm saying, what are you seeing? And then they're kind of grouping together as buddies and saying like, oh we see gray or we see black or we see black or we see gray or this kind of brown color. So you can see them all working together. And the result of that is that there's a decrease in quality. I think one really good example is you can see here this sort of crease in Zolaar's head. It's a place where the mold sort of made like sort of a little crack. And you can see that in the ISO 200 image, but you can't see it here in the 32. And I didn't change the focus or the f-stop or anything. It was all the same, just different ISO and a different shutter speed obviously to make up for it. And you can see that there's a huge lacking or a drop in the quality. You can also see the shape of this little piece right here is totally different. And that's just, you know, the gray tones are not being understood by the pixels here. And here's a great example of grain. This is grain that I made a little example for you guys to sort of show how really, really grainy things can get if you're shooting in really low light. This was like a friend holding a really small flashlight over this bench. And you can see here that it's just like, I mean the camera has no idea what to do. You can see it's just over here it's black, but it's just being like, I think I see blue or red or I don't know, might see something. And you can see that the camera really does not know what to do. And this is just because it's not working with a whole lot of information. So, you know, it's making it up. Now I'm gonna run through really quickly and show you some examples of different situations that I would use different types of film speed. You can see here is a typical like sort of overcast sort of sunny-ish day and I wanted lots of detail and I want good colors. So I took this one at 100. Now a similar sort of day, it was actually about almost the exact same lighting situation. But in this situation I wanted a deeper, I wanted a really deep depth of focus. So you can see I wanted everything like from this tree all the way back to eternity to be in focus. And so I chose like a slightly higher f-stop. I think I'm here at like f-16 or something like that, which is kind of an area that I don't usually shoot in. I don't usually shoot at such high f-stop. And I thought, okay, well that's good, but I really kind of want a high shutter speed. So I'm gonna choose 200. And 200 is also the native ISO. And we talked about that a little bit earlier in earlier slide. It's also the native ISO of my camera. So when I'm outside doing photos in sunny weather and working in the studio with good lights, I always just shoot at 200 because that's the ISO that my camera was made to work at really. All right, here's an example of when I'm out on a day, actually I would say more than 200, I probably use 400. 400 is just perfect because you can use it inside, you can use it outside, you can use it all over the place. And especially with new digital cameras, ISO 400 is a really great speed for these kind of situations. I wanted a shallow depth of field. I wanted a high shutter speed. I wanted the photo to be taken very quickly, but good quality because I wanted to get the cutest baby in the world to be perfectly in focus and not any kind of motion blur or anything like that. And I also wanted some sort of good lighting and that's just 400 is great because you get good color and everything. So if you don't know when in doubt, switch it to 400. Also another example of 400 just but slightly pushed. I actually took this image at 400 and when you push film it's when you are when you push an ISO it's when you under expose. And I think I took it at 400 but I think it was supposed to maybe be like a 640 or something like that. And you can see in the processing when I like put it on my computer and edited, you can see that a little bit of grain came out. And that's really typical when you push, when you push a field image you under expose it and then you try to make up for it by sort of adding more light later. The computer does the same thing that your sensor would do. It just kind of imagines the colors and makes them look sort of not as good as they would have if you would have exposed it correctly. This is an example of high ISO saving your buttocks. This was taken at 1600 and it was probably actually meant to be taken at about 2000. I under exposed a little bit because I just wanted to have a higher shutter speed. And you can see here how high ISO can really get ya. You can see all this grain here. This is one of my favorite photos because it was a really good memory. It was a great trip where there's a horse trailer and I was riding through the mountains back home in Montana with some friends. And this was the night we were closing down the shop and putting everything away. And this is my dad's friend Jim closing up. And this is all just lit by one little, one little tiny light bulb back here, really small. So there's not a lot of light. And so I just turned up my ISO really quickly and took a photo. But you can see the quality is just not quite there. So all right, that was your introduction to ISO and sort of some of the different applications of different ISO speeds, things like that. You can learn more at alversity.org.