The Exposure Triangle


 If you’re reading this then you are interested in taking better pictures. Maybe your pictures aren’t straight, out of focus, too dark or too light, or something else that affects the overall look of the picture itself. Much of that can fixed before you press the shutter button on your camera, you just need to slow down. I was lucky to have a friend that was a professional photographer that not only showed me the right way to use a camera, but he paid me while I was learning. My hope is I can do the same for you (minus the pay).

One of the first things you can do when starting out in photography is to learn everything you can about your camera and how it works. You can do this in a few ways, but the two most popular are 1) reading the manual that comes with your camera, or 2) by watching videos on Youtube. I personally learn better by watching videos, but I still also go through my manual from time to time.


One of the first things to learn about is what’s called the exposure triangle. The exposure triangle consists of your ISO, which is simply the sensitivity setting for your sensor or the film you’re using, shutter speed, how fast the lens opens and closes, and your fstop or aperture setting, the size of the opening your lens is set to.

ISO is usually seen in as 100, 200, 400, 800 and higher depending on the camera you’re using. Typically, the more expensive your camera, the higher the ISO can be set. What ISO does is set how sensitive your camera’s sensor is to the light hitting it. The lower the ISO number, for instance 100, the less sensitive it is to light, therefore, to get a good picture using ISO 100 you will need a fairly bright source of light. When using a higher ISO like 1600, you can get a good picture at a time when the light source you’re in isn’t very bright. Think of it this way, if you’re outside taking a picture of some flowers at noon on a bright sunny day, ISO 100 will work just fine. Now if you were to take a picture of those same flowers after the sun set you might need to set your ISO at 1600 or more. So, every time you change your ISO to a higher number, say 100 to 200, you are doubling the amount of light on your camera’s sensor. Now if you went from 100 to 400 you it would be 4 times as much light, 100 to 800 would be 8 times as much light, and 100 to 1600 would be letting in 16 times more light, and so on.


Next would be shutter speed. Shutter speed is typically shown as a fraction like 1/200, which is 1/200 of a second. For that example, that would mean when you press the shutter button to take a picture your shutter (a curtain like object that opens and closes to let light in) would open and close in 1 200th of a second. If it were set to ¼, your shutter would open and close in 1 quarter of a second. So what exactly does that mean? It means the faster the shutter opens and closes (1/200) the less light is getting in, and the slower it closes (1/4) the more light is getting in. Here’s an example of why that matters. If you had your camera’s shutter speed set to 1/200 and you took a picture and your picture was very dark, that means you need to let in more light. If you slowed your shutter speed down to 1/100 you would be letting in twice as much light. The opposite is also true. If you took a picture with a shutter speed set at 1/200 and it’s too bright you need to let in less light. Now you would increase your shutter speed to let in less light by adjusting how quickly your shutter opens and closes. So now you would go from 1/200 to 1/400. Now you have decreased the light by a half. Are you starting to see a pattern? If not, don’t worry in time you will.


Finally, we have the fstop or aperture. This is the size of the opening your lens is set at. Lens settings you’ll often see are 2.8, 4.0, 5.6, 8.0, and so on to what ever your lens goes up to. The number just is another way to control light getting into your camera. Remember above I said the aperture is much like a curtain that opens and closes? Well, the number is the size of the curtain. It is confusing at first, because a lens that is said to be wide open (letting the maximum amount of like would be at f2.8 or smaller, depending on the lens you’re using. But a lens set at f8 would be a smaller opening and letting in 8 times LESS light. Or if you went form f8 to f2.8 you would be letting in 8 times MORE light. So now if you took a picture of those same flowers at noon on the same bright sunny day and your picture was too bright and it was set at f2.8 what would you do? You would need to let in less light, right? How would you do that? You’ve just been taught a few different ways, but for now I’ll show you just using your fstop. You need to let in less light so you would increase the size of the curtain that opens and closes. So instead of f2.8 you would change your fstop/aperture to f4, or 5.6, or maybe even higher until your picture looked right to you.


Next week I’ll explain how to put everything you learned today and how it can help improve your photography! Have a great week.