Understanding Dynamic Range...

One of the most incredible things about your eyes is the range of light they can see in.

When your eyes are completely adjusted to the dark they can detect a single photon of light. You can take those same set of eyes into bright day light and completely focus on details on brightly lit objects.

Your eyes are designed to see a huge range from dark to light all at one time. This is referred to as Dynamic Range and your eye has a dynamic range of around 18 to 20 stops worth of light. On the other hand, a digital camera has the dynamic range of about 10 to 12 stops of light and maybe even up to 14 if you're lucky.

What does this mean and why is this so important to remember...well, your eye can see almost double the range of light to dark that your camera can capture. Just because a scene looks a certain way to your eye, that doesn't mean your camera will be able to capture it!

For example, if you were standing under a grove of shade trees on a bright sunny day and there was a large opening in the trees canopy above with ample sky and sun light shining through, my eyes would have no trouble seeing detail from beneath the shaded trees to the bright sky above.

Now when I point my camera at the scene and take the shot, you will end up with a very dark exposure from beneath the trees but the sky will be bright!

Why?
Your camera does not have the dynamic range required to capture the whole scene the way your eyes were seeing it. By default your camera will meter the scene to preserve the bright areas exposing for the sky and leaving the rest of the scene plunged in darkness so, you over expose to brighten the scene beneath the trees but now, the sky is over exposed with no details and blown out to complete white.

Conclusion, there's no way you can shoot this type of scene and capture the Full Dynamic Range that you can see with your eyes. When your in this type of setting you'll have to decide if it's the shadows or the highlights that's more important and expose accordantly.

Expectation of a scene based on what your eyes see will lead to as many bad photos as technical skill.

You see a scene, you capture the photo and you expect the photo to look like the scene because it looked fine to your eye.

Learn to recognize a scene that has more dynamic range than your camera can capture then make the appropriate exposure adjustments.

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