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Camera FAQ #3: How do I use the expanded ISO speeds on my camera?

ISO speed settings let you increase the shutter speed for use even in dark scenes. These settings include an expanded ISO speed feature, which allows you to expand the range of speeds available. Find out more about how you can make use of this feature (Reported by: Shirou Hagihara).


Get to know the benefits and drawbacks of using expanded ISO

A digital camera has normal ISO speeds and expanded ISO speeds. The normal ISO speeds ensure that images are of a certain quality, and are for regular use. The expanded ISO speeds, on the other hand, are outside the normal ISO range, and although they have some drawbacks, you can also expect some benefits from using them. I have summarized the benefits and drawbacks in a table below as a reference for using the expanded ISO speeds effectively.
The lower end of the expanded ISO speed is generally ISO 50, and is employed in Canon’s lineup of high-end models. However, the upper limit for expanded speeds in the high range varies depending on the camera.

*Benefits and drawbacks of expanded ISO speeds


Low ISO speed

  • Can use slow shutter speeds.
  • Ensures that the shutter speed is adequate and doesn’t become too fast in very bright conditions.
  • Opens the aperture to minimize the impact of diffraction.
  • The dynamic range becomes slightly narrower, making images more susceptible to white blowout.
  • There is an increased risk of camera shake at slow shutter speeds.

High ISO Speed

  • Less susceptible to camera shake.
  • Can use high shutter speeds.
  • Can create a grainy effect in monochrome, etc.
  • Can take hand-held shots at night or in dark places.
  • Can use slow shutter speeds.
  • Ensures that the shutter speed is adequate and doesn’t become too fast in very bright conditions.
  • Opens the aperture to minimize the impact of diffraction.

The above table is a summary of the benefits and drawbacks to low and high ISO speeds. Because the low and high ISO speed settings vary depending on the camera, be sure to check them on your camera. The low expanded speeds in particular are mostly only available on high-end models.

*Example shot taken at a high ISO speed

EOS 7D Mark II/ EF-S60mm f/2.8 Macro USM/ FL: 60mm (96mm in 35mm-equivalent terms) Aperture-priority AE mode (f/4.5, 1/4000sec, EV -1)/ ISO 25600/ WB: Colour temperature (4400K)

Even when capturing small subjects using hand-held shooting, setting a high ISO speed will allow you to obtain the shutter speed required to be able to reliably capture still shots of subjects that are swaying.

*Example shot taken at a low ISO speed

Photo by AKI GOTO, EOS 5D Mark III/ EF70-200mm f/4L IS USM/ FL: 121mm/ Manual exposure (f/18, 60 sec.)/ ISO 50/ WB: Daylight/ Filter: ND400

Expanded ISO speed settings also allow you to take shots at even slower shutter speeds. Click here to find out how to take such photos

[Part 2] Capturing Drifting Clouds with a 60 sec Exposure

Shirou Hagihara


Born in 1959 in Yamanashi. After graduating from Nihon University, Hagihara was involved in the launch of the photography magazine, “fukei shashin”, where he worked as an editor and a publisher. He later resigned and became a freelance photographer. Currently, Hagihara is engaged in photography and written works centring on natural landscapes. He is a member of the Society of Scientific Photography (SSP).

Digital Camera Magazine


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