ISO 100. Result, beautiful clean image. Anna is a blur. Useless. Option B, 1-1000 sec, F2, ISO 1600.

Result, slight noise. Anna, perfectly sharp winner. A noisy sharp photo is almost always preferable to

a clean blurry photo. Now let's introduce something that catches people out. Suppose Anna is standing

still. Would you rather shoot 1-1000 sec, ISO 3200, or 125 sec, ISO 400? Both would expose

correctly. Most people who have just learned about shutter speed pick the faster one,

but the second is usually better because Anna isn't moving. 125 sec is plenty fast enough.

ISO 400 will look cleaner. This is where photography becomes a judgment call rather

than a formula. Here's a little exercise for today.

Using your iPhone. Take a photo of 1, Anna standing still. 2, a moving car. 3, someone walking.