Practical Artistry: Light & Exposure for Digital Photographers

82 Selecting Shutter Speed

It’s All about Time

It’s All about Time

Setting the shutter speed does not set a speed; rather this

setting controls a duration of time; s

pecifically, the dura-

tion of time that the shutter is open. During the time the

shutter is open, light from the subject comes through

the lens aperture and is recorded by the sensor.

As I explained in Chapter 1, shutter speed is one of the

three components of the exposure equation, and one

of the three settings used to make an exposure. The

shutter speed setting is extremely important to almost

every exposure. But sadly, shutter speed is badly named

because the name misleads about the quantity that is

being controlled. Once you understand what shutter

speed controls (and it isn’t a speed), you shouldn’t have

much conceptual problem with the setting.

As long as you understand that shutter speed is really a

duration of time, not a speed, you’ll find it easy to work

with your shutter speed settings. So repeat after me:

Shutter speed is all about time.

I’m sure you’ll agree that a duration of 1/10 of a second

lets in one tenth the light of a duration of one second,

a duration of 1/125 of a second lets in twice the light

of 1/250 of second, and so on. Shutter speeds have a

direct, linear, arithmetical relationship to each other.

Once you are clear that shutter speed is a unit of time,

manipulating shutter spe ...