Fujifilm cameras and the Auto-ISO

Digital cameras have changed photography. In the “good old days” you bought a film: either black and white, with an ASA (ASA begat DIN which begat ISO) of 125 or of 400 or a color film with a specific sensitivity with an ASA rating of 50 like the Fuji Velvia 50 or Kodachrome 64… And that was it. For the whole roll/film. You could push the sensitivity a little bit by changing the processing but if not the ISO was fixed.

Now with digital, we have sensors with ratings from ISO 50 to ISO 3,280,000, yes that’s ISO 3 millions! The sensor has a rating of usually ISO 200, then by sending more electrical current it’s possible to amplify the sensitivity, it’s like a volume amplifier. But with more electricity comes the heat and eventually the noise. Most importantly, the ISO setting is for each image not for a whole roll of film.

Fuji like most camera manufacturers provides Auto-ISO, so the camera can decide which ISO to use within a specific range set by the user. The Fuji cameras will store 3 Auto-ISO settings:

  • ISO minimum value
  • ISO maximum value
  • Minimum shutter speed

By default Fuji tries to keep the ISO as low as possible with the aperture chosen and the minimum shutter speed chosen (by the user or by the camera).


If you shoot in aperture or in shutter priority, the Auto-ISO will use the widest aperture and the slowest shutter speed set in the Auto-ISO1 or Auto-ISO2 or Auto-ISO3 before raising the ISO.

The camera may select a shutter speed slower than the minimum shutter speed if the image will be underexposed at the max sensitivity set in the Auto_ISO.

My Settings

Auto-ISO 1

This is my everyday standard:

  • ISO starting value: 200
  • ISO ending value: 3200
  • Minimum shutter speed: 1/125s

Auto-ISO 2

This is my “lower-light” default. Mostly when I photography in black and white without flash:

  • ISO starting value: 200
  • ISO ending value: 6400
  • Minimum shutter speed: 1/30s

Auto-ISO 3

This is my flash default:

  • ISO starting value: 200
  • ISO ending value: 3200
  • Minimum shutter speed: 1/30s


With the Auto-ISO, it’s easy to set both the shutter speed and the aperture manually, while letting the camera do the rest.

I often do this with my flash exposures.