ISO (photo)

What does the ISO control?

• Depth of field

• Motion

• Noise

• Sensor Amplitude

Answer explanation

Aperture: Depth of Field

Shutter speed: Motion

ISO: Noise / Film Grain

If you increase the ISO number, what happens to your picture?

• The picture looks smoother.

• The background is blurrier.

• You can freeze motion.

• The picture has more noise.

Answer explanation

Changing the ISO number to a higher number (such as from 200 to 1600) will increase the amount of noise present in the picture, reducing the quality and color accuracy.

You should always photograph at the lowest ISO possible for your situation and aperture/shutter speed needs with digital.

• True

• False

Answer explanation

ISO in digital does not work the same as ISO in film. Therefore there are two different effects in each medium. Film results in grain, an organic looking pattern. Noise indicates a digital degradation of the image.

Your aperture is set to f/2.8 (the widest your lens will allow) and your shutter speed to 1/60 (the lowest you want your shutter speed to be handheld with a normal lens). Your ISO is set to 200, but the picture is two stops underexposed with this setting. What should you set your ISO to to get a properly exposed image?

• 50

• 400

• 800

• 1600

Answer explanation

Increasing exposure by one stop increases the light by double. The opposite decreases the light by half.

800 is two stops above 200.

(200x2)x2=800

You were previously shooting at night. Your ISO is set to 1600. You've set your aperture to f/8 and your shutter to 1/500, but your picture is overexposed by 3 stops. What should your new ISO setting be?

• 12800

• 200

• 800

• 3200

Answer explanation

Since the picture would be overexposed at 3 stops, you need to turn your ISO down by 3 stops.