Practical Artistry: Light & Exposure for Digital Photographers

110 ISO and Noise

I’ve said it before, and I’ll say it again: all other things

being equal, you’ll probably want to shoot with as low

an ISO as possible because raising the ISO increases

the noise in a photo. It’s a judgement call when “all oth

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er

things” are (or are not) equal, but the most common

situations involve circumstances in which there is no

other good way to get the shot.

Typically, it makes sense to boost the ISO in situations

in which you don’t have enough light to use as small

an aperture as you’d like (see Chapter 2) or as fast a

shutter speed as you need to freeze motion or prevent

camera shake (see Chapter 3). Add to the mix the un

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w

illingness to use a flash (perhaps because you don’t

want to disturb the subject) or inability to use a flash

(the subject is at too great a distance) and you’ve got a

perfect recipe for higher ISO.

People dancing in the dark? Celebrities at a political

rally? Kids racing around in the shadows? Motion in

the moonlight? These are all good candidates for a

boosted ISO.

Another way of saying this is that it makes sense to

boost your ISO if otherwise your exposure time would

just be too dang long.

Different cameras have differing abilities to gracefully

handle amplification of the signal that is processed by

the sensor. So it’s hard to make generalizations about

what ISO you can safely use without generating