Digital Photography Basics - What Is The Exposure Triangle?

1. Introduction To The Exposure Triangle: This tutorial is all about the exposure triangle and how you control three components to help you maintain a correct exposure. This is for those of you that are moving away from the automatic mode and work more in manual mode. It will help you stop getting confused with your settings and enable you to get more creative photographs while still maintaining the correct exposure. I'm a professional photographer with a varied client list, which keeps me interested, but also can be challenging because I'm often out on location taking photographs in different lighting situations rather than inside a studio and therefore the lighting changes. And I need to be able to adapt my settings to to get the creative image I'm trying to achieve, but also maintain a correct exposure whilst the light changes. The exposure triangle is key to me being able to do that in manual mode. And these tutorials are going to help you understand how to also start working with your camera more effectively, maintain a correct exposure, but also bring in some creative skill. And if you want to find out how the little dragon comes into the story, then you need to start watching my video tutorial. Let's get started. 2. Exposure Triangle Components: This is for those of you moving away from the auto mode, which is where the camera's doing absolutely everything for you. You may have already transitioned over to using your shutter priority mode or your aperture priority mode, But once you've become familiar with those modes, the next phase is going completely manual. The problem is when you're in aperture priority mode or shutter priority mode, you're thinking about one thing. So if you're in shutter priority mode, you're just deciding on the shutter speed. And then the camera is working out the correct exposure for you and adjusting the aperture and the ISO for you. Likewise, if you're in the aperture priority mode, you're just thinking about how big do I want my aperture to be? Which f-stop am I going to use? And then the camera compensates for your choice to make sure that the exposure is correct. Once you come out those modes and you go into manual mode, you're having to do everything. And the only way that you are going to get to correct exposure is by understanding the exposure triangle. So there's three key elements to the exposure triangle. That's your aperture, shutter speed, and your ISO. Let's start with the ISO. The ISO is the equivalent of what the film canister used to be in the old film cameras. And on the film canister, you would see a number. And you'd know from that number how sensitive the film was to light. So the higher the number, the more sensitive that film was to light. So you'd use a higher numbered film forg darker conditions. And in exactly the same way, your ISO number on your digital camera is representing that sensitivity to light. The only differences is now it's all done digitally in some kind of microchip, I guess in the back of your camera instead of it being a film canister. So that's the first thing, your ISO and the number that you use to make it sensitive, more sensitive or less sensitive to light. One of the other of the three elements is your aperture. The aperture is simply how big or small the opening in the lens is when you're taking your photo and you determine that size through your f-stop number. And you are deciding how big that aperture is, how much light you're going to let in by the f-stop number that you choose. And the third control is your shutter speed. Your shutter speed is the mechanical opening and closing of a shutter. And depending on how fast the shutter speed is that you set, depends on how fast the shutter speed opens and closes, which then determines how much time light has to come in through the aperture to hit the ISO light meter at the back of the camera. They're, the three elements that we're looking at. 3. Apertures & The Exposure Triangle: So the exposure triangle is made up of three elements. Shutter speed, aperture, ISO. But what I wanted to get really clear is that it's not about finding the correct exposure or working out the correct exposure for the photograph you're taking. It's about maintaining the correct exposure. Once you've already established what their exposure is. So it really comes into its own. Once you have figured out what the correct exposure is. And you set your aperture, shutter speed ISO to get to that correct exposure. But then you decide that you want to change one of those elements. How do you make sure that you don't overexposed or underexposed? You might be thinking, well, why would I want to change one of those elements if I've figured out what the correct exposure is, because surely that's what we use them for. Well we do. However, each one of them also has a secondary effect. And it's that secondary effect that you might want to use creatively in your image. So let's just take a closer look at that. The first effect we're going to look at is depth of field. Depth of field in its simplest terms, just means what remains in focus, in front and behind your subject. Now a long depth of field means that more stays in focus and a shorter depth of field means that the focus area is shorter and therefore, things start to blur in the foreground and the background more quickly. Photographers use Depth of Field creatively in order to make more blurry backgrounds and foregrounds so that the eye is drawn to the subject that they're focused on and not distracted by the foreground or background. For example, in this shot of the glasses they're, the subject, not the background or the foreground. And so I want to draw the eye to the glasses. And I do that by choosing a more open aperture which shortens the depth of field and blurs that foreground and background a bit more quickly. So we've adjusted the aperture to alter the depth of field for a creative effect. We've opened up the aperture to shorten the depth of field and make the background & foreground more blurry. But that in itself, by opening up the aperture, has brought in more light. And therefore we've also now affected the exposure that we had at the start, which was the correct exposure. So now we've got more light, which means it's going to overexpose the image. So what do we do? Well, it's fine. You've just got to think about balance. You've opened up your aperture and allowed more light in. So we have to reduce the effect of that light with the other two elements. So you can either make your ISO less sensitive by bringing the number down, or you can make your shutter speed faster, which means that the extra amount of light has less time to hit the ISO and affect the exposure. And as long as you balance it out. So for example, if you've opened up your aperture by two stops, you need to reduce the ISO sensitivity by two stops or make your shutter speed two stops faster. Or you can do a combination of the shutter speed and the ISO and do one-stop each, because that also adds up to two stops. It's all a matter of balance. 4. Shutter Speeds & The Exposure Triangle: Now that you know how to use your aperture to control your exposure and use it as a creative effect on your image. Let's take a look and see how you can do the same with your shutter speed. Shutter speeds are used to capture movement. And depending on which shutter speed you use, you can capture movement either by blurring or freezing. For creative effect, a faster shutter speed is going to freeze movement. And a good starting point is 250th of a second. But let's not forget the exposure triangle. Don't forget, once you've changed your shutter speed for creative effect, you've then altered the exposure. If you use a faster shutter speed, that's going to reduce the amount of time that the light has to hit the ISO, and that's going to underexposure your image. So we have to remember to change one of the other elements or a combination of the two other elements to balance out that change in the exposure. Now let's not forget the exposure triangle balance. So if you've made your shutter speed two stops faster, you've reduced the amount of time that that light can hit your ISO by two stops in order to balance out the exposure and get it back to a correct exposure. You then have to open up your aperture by two stops or make your ISO two stops more sensitive. Or you can do a combination of the two. So it would be one stop, more sensitive ISO and one stop, larger aperture. And that will balance out your exposure and get it back to the correct exposure that you started with. But you'll have the creative effect of the movement that you're trying to achieve in your image. So if you've slowed down your shutter speed, you've increased the amount of time that the light coming in has to hit the ISO sensor that's going to overexpose your image. So we have to remember to change one of the two other elements, or a combination of those two other elements to make up that change in the exposure. 5. ISO & The Exposure Triangle: ISO is primarily used for exposure control and rarely used for the creative effect. That's because the creative effect isn't really a creative effect. it's more of a 'Be aware this is what happens if you use your ISO in this way'. Now it comes into effect in low-light conditions where you haven't got the opportunity to introduce any other light source. You use your ISO to make your camera more sensitive to the low light conditions. And you do that by bumping up your ISO to a higher number. But you have to be aware that as you do that, you will increase digital noise. Digital noise is when you can see some pixelation and digital information that looks unclean on the image. It doesn't look like a really nice, clean, refined image. And it really comes into play. When you make your image larger, you'll really notice it. So if you don't like this grainy effect, then you need to be aware that your ISO has to be the last resort when you're in low-light conditions. If you've got any other options, use them before you bump up your ISO. Now this is improving. Technology in Cameras is getting better and therefore, that is becoming less of a problem with certain cameras. And it really will be dependent on the camera that you've got. Whether they put the technology into the ISO aspect. And it's really good in low light conditions. So it's a matter of experiment. My camera which is Nikon D750 is not great in low light conditions. And I will always keep my ISO as low as I possibly can when I'm taking photographs. 6. Practical Use Of The Exposure Triangle: I want to show you how to use the exposure triangle in a practical session. I'm a professional photographer and only work in manual mode because that is the way I learned. And whilst it takes more time to learn the manual mode, it does give you increased flexibility in the creative aspect of your photography and how you approach your photographic image. I'm going to show you how this works with a product shoot I did recently. And as you can see, I've already got my setup composition, the props my lights are where I want them to be, and I've got my cameras set to the correct exposure. So let's not forget the exposure triangle is all about how you maintain that correct exposure. Once you've already figured out what the exposure is. The initial settings to get to the correct exposure for this shoot, were a 100 ISO half a second shutter speed, and it was F9 aperture. So I've got it on a tripod so that I don't have to worry that that's a really slow shutter speed. and I'm also using a remote trigger, so I'm not going to have any camera shake, so that's fine. With product photography and portrait photography, you always want to separate out the product or the subject from its background. And the easiest way and the most effective way of doing this is by blurring the background. And we've spoken a bit about how you have your depth of field and how you shorten your depth of field so that you blur the background and the foreground. And then the eye focuses on the portrait or the product. With these settings it's F9, so that's quite a long depth of field. And what we really want is a short depth of field so that the product stays in focus and then the things behind and in front of the product start blurring and therefore our focus and our attention is just on the products. I started at F9 and I want to change it down to F4, this opens up the aperture. and shortens the depth of field and blurs the background and the foreground. But what else have I done? I'm now letting in a significant amount more light because the aperture is much more open. So how do I get back to that original exposure that was correct because I've now changed one of the three fundamentals? I've opened up the aperture, increased the light source. And whilst I'm achieving the creative aspect of blur in the background, I need to get back to the settings that are going to help make sure that my exposure remains constant with the initial camera settings, which was the F9 ISO 100 half second shutter speed. I'm going to let you know a little secret here, it's really important that you check your camera settings because most cameras. Can give you an option of full stops, half stops and a third of a stop. What do I mean by stops? So imagine that one stop is one unit of light. Two stops is double the amount of light. So every time you double or half your ISO, your shutter speed or your aperture, you're doubling or halving the effect of the light. Okay, I just want to show you a quick way of figuring out whether you have your camera set to full stops, half stops or a third of a stop. Now if we look at the ISO it's on a 100, I know that doubling it to 200 is one full stop. As I move it, one stop and the next number I see is a 125, that is a third of a stop. And I know that because if I count those stops from 100 to 200 (counting) one, two, three comes to 200, that's 1 full stop. So three increments is a third of a full stop. Now I can check my my f-number as well. (counting) one, two three = 1 full stop from F4 is 5.6, but it's taken me three increments to get to that. So I know my camera is set in thirds of a stop with my shutter speed (counting) one, two, three. I know that 1 tenth of a second compared to 1 twentieth of a second is exactly one full stop. And it took three movements to get to that full stop. So I know that all three of them now are set in thirds of stops, I have included a chart in this tutorial and you can easily use the charts to check to see which numbers you're seeing and from that chart, you'll be able to figure out how your camera set up. So my original settings were half a second shutter speed, F9 aperture and ISO 100. I then changed my aperture to F4 (counting) one, two, three, four, five, six, seven I would then have to change my shutter speed to (counting) one, two, three, four, five, six, seven That would be the equivalent exposure. I actually shot at 1 thirteenth of a second because the light above there was a little bit of ambient light source and that change slightly the closest I could get to the same exposure, was an additional third of a stop. If you maintain exactly the same lighting conditions, then that wouldn't be affected and you would have exactly the same exposure that I started with, but I'm now able to blur the background, get my creative effect because I've shortened the depth of field by opening up the aperture to F4. 7. Correct Exposure Starting Point: I just want you to look out for something that's in all your cameras. And that is this little graph here where it says a minus, a zero and, a plus. So in this setting here, that little point I don't know if you can see it, right here on the zero, if I change my shutter speed, which is making it faster, it's saying that I've got reduced light and it's saying that in this situation, that would be an underexposed image. If I close down my aperture, it's becoming more underexposed. So ideally what you want to do when you're first starting out is use this as your guide. That set of settings, 15th of a second, 6.3, ISO 100, as far as his camera is concerned, would be the ideal setting for a correct exposure. It's not going to be absolute, but it's a really good starting point if you're just starting out. Because what you can do is use that as your guidance to get to your initial exposure setting and then adjust it accordingly. See how dark that actually is? And so whilst the camera is saying that's the correct exposure for me, that's too dark. But the reason it's saying that is because it's reading the bright light coming in. See how that's flashing? That's saying it's overexposed, but of course all the detail around the outside is not so good. Use it as your starting point, but don't rely on it to give you the absolute correct exposure. And then adjust from there. So it's already overexposed where the door is. So I'm going to keep the sharpness because I want that nice detail. But I'm going to open up. And now suddenly you've got the same overexposure with the light coming through, but it's a little bit better. I still think I could get away with a little bit more lie. And obviously I'm just using the ambient light coming in. Hence, the incredibly slow shutter speed. I would say maybe one more. I'd give it another go like that And I'm getting happier now because I feel like there's more detail in the overall image. And I'm happy to have that blown out area in the middle there because that's going to be blown out even if the rest of the image is underexposed. So that's just a way that you can get yourself going, get started and figure out what you want to do and then adjust from there.