Are you ready to finally understand Exposure?
What is the exposure triangle?
The Exposure Triangle is one of the best-known concepts to “explain” how photography works. Unfortunately it’s also the biggest source of confusion in photography.
On this website, I will stop that confusion and teach photography so that you actually understand.
If you register for free on this website, you get access to my download section with free Lightroom profiles and lots of cheat sheets that I created to help you learn photography the right way.
Exposure in Photography
What Does Exposure Mean?
When photographers talk about exposure, they actually mean image brightness, which is not entirely correct and causes confusion. An image can be:
2. What is it Exposed to?
To the scene you want to photograph. So basically to more or less light, because the scene can be brighter or darker.
So light is the source of it all. Photography is Greek. Some people say it means painting with light, but it really means the light paints so the light is the artist and the source of our images.
Let me repeat that, because it is so vital to understand exposure:
The three settings of the Exposure Triangle are just a reaction to the amount of light
in the scene you want to photograph"
What are the Components of Exposure?
Before I explain the components of exposure. Please keep in mind. Every single one of the components has an effect on image brightness. Changing one of them will make the image brighter – but only, if you don’t compensate with another one. If you are not in manual exposure mode, your camera will automatically compensate with another setting if you change one!
1. The Brightness of the Scene
Since you learned that exposure is all about light, the most important component of exposure is so-called scene luminance, which is the correct term for scene brightness. Scene luminance (scene brightness) is simply the single most important ingredient of image brightness. Once you keep that in your memory, the Exposure Triangle will be much easier to understand.
Quite logically, the brighter your scene is, the brighter the image will get, if you don’t change any camera settings.
For us humans that is sometimes hard to understand because our brain tries to provide our mind with constant light levels. In reality, the light levels change dramatically.
Consider you are photographing your kids playing basketball in a gym. You’d think it is considerably bright in there, but the truth is: the light level in a gym is usually 250 times darker than outdoors. That is massive!!! We don’t realize that because our brain tricks us. Our cameras on the other hand can only use what is really there to expose our images, so in photography these varying light levels force us to make compromises.
Summary: brighter scene – brighter image
To get into the camera, the light of the scene we want to photograph, passes through the lens. In that lens is a hole, called aperture. The aperture is variable in size, giving us the option to block some of the light and therefore reduce brightness of the image.
Compare the aperture to a window with blinds. The more you close the blinds, the more light will be blocked and the darker the room will get. Same with the light that enters the camera.
Summary: bigger opening – brighter image
3. Shutter Speed (Exposure Time)
After the light passes the aperture, it almost reached it’s destination, the camera sensor. Before it can start exposing the sensor, it is blocked by a “door” (shutter). Just like with a real door, if you open it, you will let light in. To open that door in our camera, we have to press the shutter button.
The amount of time the shutter is opened to expose the sensor to the light in the scene is called shutter speed. But the correct term would be exposure time. Why exposure time is the correct phrase and why photography is much easier to understand, if you use that term instead, will be explained on a dedicated page, when you follow the link below.
Summary: longer exposure time – brighter image
With the closing of the shutter, exposure has ended!!!
Quite logically, if you close the door (remember, that’s what the shutter is), the light is blocked again. And if the sensor is not exposed to light any more, exposure has ended too.
Do you Miss ISO?
After having another look at the exposure triangle above, you might be surprised that I didn’t list ISO under the components of exposure.
ISO for many people is some kind of a mythical figure – the wizard of the camera settings.
ISO is the Gain
The truth is, it’s much easier than that. ISO is the gain that is applied to the amount of light your camera sensor has “recorded”. And being exactly that, the gain, it has nothing to do with exposure. It is applied by the cameras processor long after the shutter has closed.
Nevertheless, the gain has an influence on image brightness
Summary: higher gain (ISO) – brighter image
Why is the Exposure Triangle Confusing?
That leads to massive confusion among beginner photographers, who think the camera settings are a magic mix, while in reality they are just a reaction to the amount of light we have available. When you understand that photography is all about light, everything else will be much easier to understand.
Now let me recommend learning how each camera setting affects your images. In the end I will introduce you to a cheat sheet that is a much better model to explain image brightness and will help you understand exposure and photography once and for all.
Exposure Triangle FAQ
Here is a list about the most frequently asked questions regarding the Exposure Triangle.
If you have a question, feel free to ask below and I will add it to the list.
You learned above that the single most important source of image brightness is scene lumincance. According to that, the camera settings depend on how much light you have available and what you are trying to photograph. If you continue this “course”, you will find out that for example shutter speed depends on how fast the subject you are photographing is moving. Don’t worry, it all sounds much more complicated than it is, continuing step by step on this page, will help you understand, which is much better than learning anything by heart.
Trust me: you don’t want an exposure triangle cheat sheet. What I will rather give you is a cheat sheet that will make you understand photography. Let me try to convince you to keep on reading the easy to understand lessons here on the page first though because understanding the components of exposure and what they do, will help you much better.
Ready? Here is the link to the next “lesson”: Scene Luminance
Unfortunately people hardly ever question what they have been taught by others. But there are numerous great photography teachers out there teaching photography without ever mentioning the exposure triangle.
The exposure triangle lists ISO. ISO is an electronic gain and has nothing to do with light. It’s almost the same as adding image editing to the exposure triangle.
On the other hand the triangle doesn’t list scene luminance despite it being the most important part of exposure.
Please comment below. I will constantly update this section with new questions.
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