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

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The exposure triangle and reciprocity

The exposure triangle and reciprocity

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

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The exposure triangle and reciprocity

- Earlier, I raised a question that you might already have been wondering about. Why are there two mechanisms for controlling how much light strikes the sensor? Why do you need both aperture and shutter speed when either one lets you lighten or darken an image? For that matter, why do you then need a third parameter, ISO? The reason is that shutter speed and aperture do more than simply control the brightness in your image. Think about a two-second exposure. Two seconds is actually a pretty long time. In that time just now, my heart beat a few times, I did some breathing. I pondered some of the deeper questions of meaning and existence. And because of all that, I probably did not hold the camera very steady. And realistically, if I had tried to hold the camera steady, I probably would have just made things worse. This should be pretty intuitive, but if there's movement within the frame while the shutter is open, then that movement is going to appear blurry in the final image. Movement…

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