Our next topic, ISO, is very closely related to what we were just talking about in the previous section on sensor size. And so, ISO in this case, is referring to the sensitivity of the sensor and so, this comes from an International Standards Organization, so that when you operate Canon, Nikon, Sony, Fuji, et cetera, things are basically the same between them. There's some subtle, slight little differences in there, but for the most part, we can all speak in a common language when it comes to exposure. For most cameras, 100, and we're not gonna worry about why it's 100, it's just 100, is what's known as the base or native sensitivity. This is where your sensor is at its peak performance, it needs, once again, that Goldilocks, just the right amount of cooking to make it right in there and so, you do too much and it gets overexposed, you do not enough and it's too dark and so forth. And so, 100 is the sensitivity, where your sensor is generally gonna be at its best. Now I do put an aster...
isk on there, because some cameras are different. One of these cameras up here is at 160, there's another camera that is 64, there's another camera that's 200, but about 80% of the cameras, the best sensitivity is ISO so that's what we're gonna work with. You can bump up the sensitivity to and then it becomes, essentially, twice as sensitive to light, so whatever light that's coming on there, it boosts the signal by two times and makes it brighter. And so, it's kind of our magic bullet, if it's not bright enough, we can just raise up the ISO and we can work in lower light levels and so, cameras will go from 1x, 2x, 4x, 8x, 16x, 32x and the numbers will keep going up and up and up. Now there will be a fall-off in quality that I'm gonna show you here in a moment, so ideally, you wanna be shooting at the lowest native sensitivity of your camera. How do you figure that out? Well, it's generally the lowest solid number in your camera. So you might have something that looks like this, generally speaking, 100 is gonna be the lowest number you're gonna find on most cameras and that's where you're gonna get optimum image quality. When you go from 800 to 1600, you are raising the sensitivity a full stop, when you go from 800 to 400, you are cutting the sensitivity in half, you are making it less by one stop, so it's a linear scale, so it's like the shutter speeds, you double it, you double it, you get a double result when it comes to the amount of light that you're doing in there. And so, this one's pretty easy to follow in doubling from one number to the next. Now many cameras will allow you to set 1/3 stops, which are these numbers in between and that's just for being very precise if you want. Some people don't use these, just 'cause they wanna make larger steps, some people get very, very specific about where they wanna be and they can set that in there. Some cameras have it and some cameras don't. Now some cameras will have a low or a high setting and what this L1 means here, is it's one stop lower than the lowest setting. The lowest setting is 100, so L1 would be equal to 50. Now this is kind of dumb, they should just call it 50, it is 50, but it does clearly indicate that it is kind of outside the normal range and so, what I believe is going on, and I still don't have confirmation on this, is that when it does this, it is being changed in the camera via software, rather than a physical change in the camera. And so, on the high setting, some cameras will have a High 1/2/3, various different names or logos for that and so, High 1 would be 12,800, which is one step beyond and so, it's a place that you're not gonna, generally, do very much photography, but if you really needed to work under very low light, you could do that. Now there will also be an Auto option. Now Auto means that the camera is gonna figure out the right ISO for a particular situation and I think of Auto ISO here, the same way I would imagine a race car driver thinks about automatic drive vs stick drive in a car. Race car drivers are usually pretty specific about what gear they wanna be in for exactly as long as they wanna be in that gear and most serious photographers are usually pretty specific about what ISO they would like to be, but by putting this in Auto, the camera will automatically figure it out for you. How does it know what ISO to use? Well, what it's doing is, it's looking at your shutter speed and it's basing your ISO on your shutter speed and the problem is, in my mind, with Auto ISO, is that it assumes a lot of things that are going on or may not be going on, depending on what you're doing. It is trying to give you a shutter speed fast enough to handhold the camera and/or lens. That sounds nice enough, what if your camera's on a tripod? Then it doesn't know and it would be a dumb idea to have it on a tripod in those cases for that. And so, I encourage everyone who is new to photography, take it out of Auto ISO, slow down and think about what you're doing. There are plenty of cases where there are serious photographers who use Auto ISO, but they're fully aware of where it is at all the times and they're just making sure that it's staying in the right range of where it's supposed to be and so, don't rely on this to begin with. If you've taken the time to take a whole class on photography, you wanna try to do things right. It's something that you can throw into the mix later on, but start with it in manual and I'm gonna walk you through on how to set it and so forth, of course, as we get through this class. Now as I mentioned, as you go up to higher ISO's, it's gonna lower the image quality, because what it's doing is it's... As I bring this up here. On the highest setting here, 102,000, it's taking the amount of light coming in the camera and it's just boosting it. It's like if you had a microphone and you're trying to get the microphone more sensitive to sound, you would turn up the volume or the gain on it and it would start picking up all sorts of other little things and there'll be problems in there. And so, it kind of looks like grain from the days of film, but it's what's known as visual noise and the problem is, is that there is very little information coming into the sensor and it is trying to amplify that information and it's not always the best quality information and this is why you wanna shoot with the lowest ISO as possible and so, generally speaking, I try to shoot at ISO 100 all the time. The reality is that I need some help with my shutter speeds and I'm at 200 and 400 and 800 quite frequently and with modern cameras, there is a very little difference between 100 and 800 on most cameras. It's only when you really get up to 6400 and 12, that you start noticing a pretty steep fall-off in quality, but the rule is pretty simple, just try to keep it as low as possible. So let's look at some photos and talk about why I chose to shoot them at a variety of ISO's. So our first photo at ISO 100, landscape photography. The subject, generally speaking, is not moving. Yes there's a waterfall, yes there are clouds, but that minor movement does not matter in this type of photograph here. My camera's on a tripod, so I can use any shutter speed and as I go through all of these ISO's, what you're gonna find in common is that, I'm talking about ISO, but I am thinking about shutter speed. Where is my shutter speed and is my shutter speed appropriate for that situation? When I shoot at ISO 100, I am getting the optimum image quality from my camera, the best possible picture I can get, which should be a goal of yours for everything. What's the best picture I can take? And from a technical aspect, we can get in and we can blow it up and we can look at the details and it's all very clean and there's not noise and grain and things like that. All right, now I'm at ISO 200. Why did I choose 200? Well, can you see I was not able to use a tripod on this photo? I had to handhold this photo and so, I had to be considerate of what shutter speed I could handhold the camera at and I needed just a little bit of a help to give me a slightly faster shutter speed, so that I could do this shot handheld. Whenever I shoot action and sports, I am almost always needing 400 or higher in the ISO section, because I'm typically shooting at 500th or 1000th of a second to stop the action and if I choose a very fast shutter speed, I need to compensate for that with a little bit higher ISO setting. So as the light levels get darker, that's generally when we're using higher ISO's, not always, but generally speaking. Now there's not a lot moving, but there is one character who might move and I needed to set a shutter speed that would protect me from moving, if he should move in this particular photograph. It's not a real bright environment, but I have people that are moving around more casually, so I probably needed a 60th of a second for my shutter speed. With the light level in here, I needed to boost my ISO up to 1600. If those people were not there and I just wanted to grab a photograph of all the fabrics that were there and I had a tripod, I would be down at ISO 100 and let's see, if I'm at 60th, I'd be at 30, 15, eight, I'd be down at a quarter of a second, which is fine, the fabrics are not moving in a quarter of a second. More movement, more low light, needing a higher ISO. It's pretty rare that you need to go beyond 6400, so obviously very low light in this aquarium, there are some subjects that are moving around and so, I'm choosing a shutter speed that still gets me sharp photos, but the 6400 allowed me to have an image that is bright enough that we can see properly. So with ISO's, technically, we want to try to keep it as low as possible, for most cameras, that's gonna be ISO and we'll bump up the sensitivity on an as needed basis and so, we're gonna keep the ISO low and we're gonna raise it when we need faster shutter speeds. And so, if you need a faster shutter speed, 'cause the gymnast is really tumbling quickly, that's when you need to bump up the ISO a little bit.