One of the things you have to learn first about photography is what does exposure means, and how do we get a good exposure on a picture, as we’re supposed to take properly exposed photographs. We could define exposure as the amount of light that enters into the sensor of the digital camera (or the photographic film if we’re shooting on film) and is determined by de shutter speed, lens aperture and the general ambient light.
Why is this important? Because if there’s too much light reaching the sensor, and the picture is overexposed, we’ll see everything too bright and white. On the other hand, a photograph will be underexposed when the picture, is too dark and has too many shadows on it. What we usually intend to do is get our photography with the right amount of light and shadows, making it not too bright, and not too dark.
How do I know if the photograph is poorly exposed?
There are two tools we can use to be sure our photography is well exposed, the first one will be the histogram, this is a graph that shows the brightness of the pixels in the picture, on the left we have the darker ones starting in 0 with black, and the brighter ones will be on the right side, ending on 255 with white. When people talk about low-key photography, one of its characteristics is having most of the pixels on the histogram to the left, while a high-key photography would have them on the right side. While the right exposed photography should try to have the most of it on the middle.
The second one are the metering models, this means that your camera is going to measure the brightness on a specific area of the scene, or the object we’re shooting, and according to that brightness is going to set a different kind of exposure. Different types of metering could be Matrix, when the camera is going to take the settings considering the whole area, Center metering will take into account a more specific part of the picture, but still covering quite a big area of the picture, and Spot will be the most specific one, where the value of the light will be taken from a small spot in the center of the viewfinder.
Of course, the exposure is just a technical part and a theoretical way of taking pictures “correctly”, and as begginers we need to know how to make it work with pictures with a correct exposure, but also we can’t forget that maybe sometimes having a photograph well exposed is not what we’re looking for, as we are aiming for a darker ambient, or maybe a lighter one, and we’ll have to have in mind that this are rules we can breake if needed, for the good of our photograph.
I will explain to you how to work out the exposure triad on next posts, have you found this post useful? Don’t forget to like it, comment and share then! I am glad we can walk this road together!!
Nucky Dana 
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