What is Exposure in Photography?

When taking a photograph, we want to accentuate the best parts of the scene, while making sure that our camera settings aren't adversely affecting the final image. In the field, we need to pay attention to the "dynamic range", which is the difference between light and dark areas of your shot. We might shoot a landscape on a particularly sunny day, and some of our images may appear "blown out" (or overly bright). To avoid this, we need to pay attention to our exposure settings. Below, we've outlined how to adapt to light sources and create great exposures, so that our subject looks as appealing as possible.  

What is exposure in photography?

Every exposure depends on three parameters: shutter speed, ISO, and aperture. Essentially, these settings form a triangle, and each side of the triangle affects the others. To find the perfect triangle for your scene, each parameter must be adjusted until they are all in balance. In the past, point and shoot cameras had limited exposure settings, and you couldn't change the shutter speed or aperture, so you were forced to shoot daytime and flash photography. Today, you can adjust this figurative triangle to capture amazing sunsets, breakneck action shots, and late-night scenes. Let's break down the triangle's three sides:

  • Aperture: This setting allows us to measure the diameter of our lens' entrance pupil, which has an effect on brightness and depth of field. As our aperture gets larger, more light hits the camera sensor and brightens the scene. Measured in "f-stops", apertures are a fraction of focal length over the entrance pupil diameter (like f/1.4 and f/2). 
  • Shutter Speed: Apart from the lens' diameter, light is also limited by the camera shutter, which opens and closes for each photo. The longer the shutter stays open, the more light hits the camera sensor. Apart from light, shutter speed also has a huge effect on motion. Depending on our creative goals, we may use a fast shutter speed to capture a racecar, so that the subject stays sharp in our images. On the other hand, you may prefer a more dramatic blur effect that emphasizes motion, which you can achieve with a slower shutter speed.   
  • ISO: Lastly, we can adjust our camera sensor's sensitivity to light. This has a direct effect on the other two parameters, because a higher ISO allows you to get away with a smaller aperture or faster shutter speed. However, high ISO settings introduce more noise in our photos, so it's better to use the lowest possible ISO, and then adjust the other parameters to make a perfect triangle. 

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