Absolute Beginner's Guide to Digital Photography

Focal Length and Digital Cameras

Lenses for 35mm cameras have a different focal

length on a digital camera. The CCDs used in these

cameras are physically smaller than a 35mm

frame. For this reason, lenses used on digital cam-

eras (with removable lenses) have a longer focal

length. In other words, a 50mm lens will actually

be 80mm on some digital cameras.

If you already own lenses for a traditional film cam-

era and are shopping for a digital camera that will

work with them, find out what the focal magnifier

is for each camera—it varies depending on the

manufacturer and even the model line. CCD and

CMOS sensors in these cameras vary greatly in size.

Long Focal-Length Lenses

A long focal-length lens provides greater image magnification and a narrower angle

of view than a normal lens. For a 35mm camera, a popular and useful long focal

length is 105mm. For a camera using 2 1/4×2 1/4-inch film, the comparable focal

length is 150mm. For a 4×5-inch view camera, it is about 300mm.

Long lenses are excellent when you cannot or do not want to get close to the subject.

They are also preferred for portraits; most people become self-conscious when a cam-

era is too close to them, so their expressions are often artificial. A long lens also

avoids the kind of distortion that occurs when shorter lenses used close to a subject

exaggerate the size of whatever is nearest the camera—in a portrait, usually the

nose (see Figure 4.4).

CHAPTER 4 THE IMPORTANCE OF LENSES 49

Conversion factors for

lenses will cease to be an

issue as fewer manufacturers pro-

duce 35mm cameras. In the

future, you’ll have to use a con-

version factor for traditional film

cameras because all lenses will be

for digital!

FIGURE 4.4
A short focal
length lens (left)
distorts a sub-
ject’s nose. Use
a longer focal
length lens
(right).