birthday peak photograph This negative was exposed on a completely overcast day. Most people think an overcast sky is dark. This is because they are unconsciously comparing it to how they remember the sky on a bright, sunny day. In fact, an overcast sky is almost always the brightest thing in a scene. Unless there is another source of light, such as a light bulb, everything else must be darker because nothing reflects more that 100% of the light falling on it.

Vision is a complex process. The lens of the eye focuses a two dimensional image on the retina at the back of the eye. The eye then converts these two dimensional images into electro-chemical impulses, which the brain uses, along with what it has seen in the past, to create what we perceive to be a three dimensional world, with objects of various shapes, colors, and brightnesses. The brain does this automatically and instantaneously. If we see someone drop a basketball, we do not wonder whether it is a disk, which will fall flat when it hits the ground. Instead, we know that it is a ball which will bounce back up into the person’s hands.

However, sometimes we get fooled, as when we perceive an overcast sky as being dark when it is actually the brightest thing in our field of vision. I believe one of the most powerful features of photography as a visual art is its ability to reveal the world as it really is, not just as we perceive it to be.

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