How Digital Photography Works

(^120) PART 2 HOW DIGITAL CAMERAS CAPTURE IMAGES
How Digital Tech Changes the
Way Lenses Work
So far, our look at how lenses work has applied to the traditional film camera as well as digital cameras. So much so,
in fact, a reader might be tempted to believe there’s no difference between film and digital cameras as far as optics
go. But the differences are significant. They arise out of the nature of the electronic image sensor that replaces film.
We’ll be looking at the image sensor in microscopic detail in the next chapter, but while we’re talking about lenses,
let’s look at how digital sensors transform the power of lenses while wreaking not inconsiderable confusion.
Most image sensors are significantly smaller
than a 35mm frame of film. There is no
standard for the size—or proportions—of
the chips used to replace film. They vary
from the size of a grain of rice to, on a few
very expensive cameras, the size of 35mm
or 2 1/4 ×2 1/4 medium format film.
1