In the previous video we learned how to set up shutter speed on our DSLR or any camera with manual controls as part of the exposure triangle. The next step is to adjust our aperture so that we can get the proper exposure for whatever lighting we're in, whether it's bright lighting like outdoors or if it is low lighting indoors at a concert or something that just doesn't have a lot of light. So if we take a look at the lens I have here, this is a 50 millimeter F1.4 and I have it open all the way at 1.4 and look, you can see completely through the lens. There is no blades that you can see keeping any light out. So as much light as this lens will let us pass through it, F1.4, that's what it's at. Now if I increase the aperture all the way up to F14 you can see the blades are really closed down and it's a really tiny hole. This lens at F14 is not letting that much light get through. And as a consequence of having a smaller aperture, less light getting through your lens, more things in the background are going to be in focus. Let me show you what that looks like right here on this shot. Alright, so I've taken the lens all the way down to 7.1 which is a big difference from where we were at at F2.8 and more of the background is going to be in focus. However, the consequence is that the image has also gotten darker. So part of that exposure triangle is when you change one setting, we've changed the aperture, you have to change another setting to make the exposure correct. And that's why knowing how the three parts work together will help you set your exposure. So since we're leaving shutter speed as it is, I've had to increase the ISO. In this case, it's all the way up to 2500 which is a really noisy ISO on the Canon 60D, which is what I'm shooting on currently. You may or may not be able to tell the difference, but it's not ideal to shoot that high. So normally I would shoot at a larger aperture, meaning more wide open, more real light into the camera instead of the artificial light which the ISO is doing for us. But you may not have much of a choice. Now one thing you can do when shooting outside where it's really bright is get a variable ND filter or just an ND filter which puts some, it's kind of like sunglasses for your lens and allows you to shoot at those large apertures while still being outside. Because even if you shoot at your lowest ISO, it's still too bright to open up your lens or open up your aperture too wide. Okay, so now I've opened up the lens all the way to F1.4. That's the largest aperture you're going to get on this Sigma 30mm F1.4. And I'm letting in as much light as this lens will allow me to let in. And as a result, you're seeing the background is now much blurrier. On the upside as well, it allows me to shoot at a lower ISO. So I'm only at ISO 200, which is 2300 less than we were shooting before where this camera shoots really clean videos. So it's a give and take. You have to decide how much do I want to focus, how much ISO do I want to use. But again, we're just dealing with aperture. So that is how aperture works. A couple of different things you can do depending on your gear, but a lens with a nice large aperture capability really lets you do more in terms of getting exposure, getting more real light into the camera. Alright, ask any questions that you have in the comments and I will see you next time. So on an average shoot, that's where we would stop. The shutter speed really is sort of a set it and forget it. Set it. And it can be a little limiting in DSLR video, but I'm going to show you how to break that rule as long as you know what you're doing.