Today I’ll explain how they work together in order to achieve a correct exposure.
In your DSLR camera, you will find an exposure level graphic like the one you see here. The aim is for the pointer to be at position 0. This means the image will be properly exposed. If the pointer is to the left, it means the image will be underexposed (too dark). If, on the other hand, it is to the right, the image will be overexposed (too light).
In future posts, I will go into more detail about the different modes your camera has, such as Aperture Priority (Av), Shutter Priority (Tv), and Manual Mode. This post applies to manual mode.
As an example, imagine you set the shutter speed to 125th of a second, at an aperture of f4. When you half press the shutter button, take a look at the exposure graphic and see where the pointer is.
If the pointer is to the left (say, at -1), the image will be underexposed by one stop. So, you must allow more light to enter the camera. This can be accomplished in one of two ways. You can either decrease the shutter speed (to 1/60), or you can increase the aperture (to f2.8). Both ways will make the sensor capture more light. There is a third way, and that is to increase the ISO. But it should only be used as a third option, when you don’t want (or can’t) change the other two variables.
If, on the other hand, the pointer is to the right (say at +1), this means the image will be overexposed by one stop. What you must do is allow less light to enter the camera. You can either increase the shutter speed (to 1/250 of a second) or close the aperture (to f5.6).
The image on the left sums up the exposure variables in a graphical way. Hopefully, you should be able to look at it and understand what each does and how it affects the final picture. Take some time to study it, and then go out and make some images using what you’ve learned. The best way of learning anything is by doing it.
Remember the words of the great photographer Henri Cartier-Bresson, “Your first 10,000 photographs are your worst.”
Here are the articles on each of the exposure triangle variables:
If you have any questions, please share them in the comments below.