From the course: Photography Foundations: Exposure (part 1)

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Autofocus basics

Autofocus basics

From the course: Photography Foundations: Exposure (part 1)

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Autofocus basics

- As you may recall from high school biology class, there are two types of light-sensitive cells in your eyes, rods and cones. Cones are the color-sensitive cells, and most of the cones in your eye are gathered into a very small area at the back of your eye called the fovea. The fovea is responsible for the focused part of your field of view. Now, it's not immediately obvious, but the only part of your entire field of view that is actually in focus is an area roughly the size of the tip of your thumb when it's held at arm's length. That's this little bit, right here. Now, if you don't believe that, give this a try. Get a piece of paper that has some text on it, I've just torn a page from a magazine, you can rip one out of a book or something. Hold at arm's length, and put your thumb over some of the text. Now, without taking your eyes off of your thumb, keep them locked there, pay attention to the text that's around your thumb. You'll realize you can't read it, it's out of focus, and…

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