Light is responsible for everything we see on the big screen. As open-ass cinematographers use light in telling their stories, darkness is also used in telling stories. To capture the range of human emotions through light and darkness, it is fundamental to understand the three components of the exposure triangle, which is aperture, shutter speed, and today's topic, ISO. So how does ISO work? Back when filmmakers shot exclusively on film, different film stalks at different speed or sensitivity to light. The film's sensitivity is what we call ISO. ISO was derived from the Greek word ISO, which meant equal. In today's digital camera technology, ISO is to the sensitivity of a camera's sensor rather than film. Apica and shutter speed would physically control the amount of light led into a camera. Also, aperture works just like the human eye. It closes to let in less light and opens to let in more light. Whereas the ISO controls how sensitive the camera's sensor is to the light that hits it. Lastly, the shutter speed controls how long light would hit the sensor. I already made a video on aperture and shutter speed, which I've left links to in the description below. You can check them out after this video. A lower ISO value makes the camera's sensor less sensitive to light, making the image darker. A higher ISO value makes the sensor more sensitive to light, making the image brighter. When determining the exposure of a shot, it is most common to adjust your ISO after your aperture to get a decent shutter speed. So let's take a question like, why would the cinematographer change their ISO? Let's take a look at a couple of scenarios. One would be low light. The film 1917 spans various takes to create an immersive 360 experience. This meant that cinematographer Richard Dickens had to light many of the darker scenes with practical light, visible on screen, while still retaining a deep focus. Look at this. It's massive. In other words, Dickens had to contend with less light and a closed aperture. Also remember to get a larger depth of field, you would have to close your aperture as much as possible, but this means less light would enter your sensor. So to pull this off, he needed a camera that could handle extreme low light situation, so he decided to go with an A-re-alaser mini-elep. Very thankful for this camera. Thank you very much. Certainly served our purpose very well. The LFI could rate it at 1600, because there's all the night scenes and the interiors. It's quite a lot of footage at night in those little bunkers. And so why would Dickens go in for a camera like an A-re-alaser mini-elep? It's basically because of its high ISO. It allowed Dickens light minimally while closing a aperture to achieve a larger depth of field. However, there is a side effect of increasing your ISO, which every cinematographer should be aware of. Noise and rain. Increasing your ISO may help brighten up your shot, but there is a bit of an issue to it. If your ISO is too high, your camera sensor would become too sensitive and would create noise and rain. Let's take this low light shot as an example. This image is clearly under exposed. To properly expose the shot without compromising your aperture or shutter speed, let's try increasing the ISO. Notice how increasing the ISO value brightens up our shot, but also produces more noise. Another question pops up, which is how do you minimize the noise? A pretty simple answer. Get to know your camera. That's certainly the best way for me to put it. Every camera is a little different, so it's imperative to understand its particular settings. For instance, the dynamic range and native ISO. The dynamic range measures the limit of how dark and light an image can be without losing details. So a larger dynamic range results in more details and color range. Adjusting the ISO in either direction moves that range, sacrificing either the highs or lows in the process. As a general rule, to shoot an image with less noise and greater range of color, you want to shoot as close to as possible to what we call the native ISO. Every digital camera has a native ISO specific to that camera. For instance, the Alexa Mini's native ISO is 800. Although many cinematographers do their best to achieve really good looking images, some cinematographers take advantage of grain and noise because of the texture, which can bring a unique quality to a shot. Film photography is a chemical miracle and it always looks different, always looks real. There's grain number one and the grain is always moving. It's swimming, which means that even in a still life of let's say a flower, that flower is alive even though it's not moving because the film itself deals with the images alive and that's the difference. What you just had Sporberg speak about is green and not digital noise. What are you doing? I was filming this dead bird. Why? Because it's beautiful. Keep in mind the clear differences between the two. An image captured on film strike produces film green during the chemical base it takes when it's being converted. You never quite know what you're going to get after the film takes a bath and exposes the positive from the negative. This is not to be mistaken for noise, which is when the ISO is pushed too high on a digital camera producing a less desirable look. However, some filmmakers intentionally use a high ISO value to create noise, which is to be assumed as an analog look reminiscent to film green. Since the photographer Brandon Trott uses this quality in his film, the disaster artist. He actually shot the movie in 3200 ISO and added a digital noise at boost purely for style. I think I don't like things that look super nice. It gives you a variety of stuff that's interesting texture stuff that you can reach out and touch and that's sort of where I'm always after a little bit. Whether your cinematography style utilizes low or native ISO value for a college look or you're looking to use high ISO value to produce style, understanding ISO is crucial to achieving the shots you've imagined and to fully understand ISO you must learn how it works with aperture and shutter speed within the exposure triangle. I've provided links in my description below leading to aperture and shutter speed and this video all adding up to make up the exposure triangle. If you love this video, kindly give me a sub and hit on the notification bell icon to get notified of my newly posted videos. Until my next video, peace out.