• Exposure is a combination of ISO, aperture, and shutter speed. • In Aperture Priority, the ISO and aperture are set and the shutter speed varies. • In Shutter Speed Priority, the ISO and shutter speed are set and the aperture varier. • In Auto ISO, the aperture and shutter speed are set and the ISO varies.
Auto ISO is useful when you need to set both the aperture for depth of field control and shutter speed for motion control.
I have shot Auto ISO for these subjects: • Early morning/late afternoon wildlife or birds. The light changing as time passes. • Theatrical performances, again where the light varies from one part of the stage to another or from scene to scene. • City walks, where are sometimes I am shooting in sun, sometimes in shade.
Implementing Auto ISO varies from body to body — Nikon has tweaked it through the years — but generally you have to turn it on and then set a minimum and a maximum ISO. Some bodies will also allow you to set a minimum shutter speed.
Jon Kandel A New York City Nikonian and Team Member Please visit my website and critique the images!