The Canon EOS Digital Rebel XSi/450D Companion

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Chapter 5

Photography 101

THE FUNDAMENTAL THEORY OF EXPOSURE

In this chapter, we’re going to take a break from cameras and computers

and focus on basic photo theory. In the old days of manual cameras,

you couldn’t learn to shoot without certain fundamental knowledge.

With today’s automatic cameras it’s possible to take great photos

without having the slightest notion of how different parameters

affect your image. However, you’ll most likely find that shooters who

do understand the basics have a broader creative palette to work with

and can push their photography further. We’ll be using the concepts

covered in this chapter through the rest of the book.

CHAPTER 5

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In Chapter 2 we took a quick look at the anatomy of your Rebel XSi, and you

learned something about the architecture of an SLR camera. In that discussion

I mentioned the image sensor in your camera. As you already know, in a digital

camera, the image sensor takes the place of a piece of film and is the mechanism

by which the camera can “see” an image.

e image sensor is a chip that is mounted parallel to the back of the camera so

that the light focused by the lens hits it head-on. In the Rebel XSi, the image sen-

sor is the same size as a piece of APS film.

e image sensor in your Rebel XSi is a large silicon chip ...