Get Better Focus in Your Digital Photos by Resetting the ISO

– by Laura Mauney

Capturing clear and correct focus with point and shoot digital cameras, including smart phone cameras, can be a roll of the dice sometimes.

I finally discovered one fixable reason after noticing that the ISO was a mere 80 for a disappointing shot I took with my smart phone around dusk, where natural light was far too low for a likewise low ISO.

Wildflowers photographed at dusk with an automatically set ISO of 80.

Wildflowers photographed at dusk with an automatically set ISO of 80.

From then on, I took the time to manually reset the ISO for every shot based on classic rules, and my odds of getting the focus I wanted shot up to an almost guaranteed win every time.

Iris photographed in bright sunlight with a manually set ISO of 100.

Iris photographed in bright sunlight with a manually set ISO of 100.

When the ISO number is low, the camera sees less light. When the ISO is high, the camera sees more light. At the display level, low ISO creates a sharper effect, as with the second photo, and high ISO creates a grainier effect, as with the first photo.

ISO controls are usually available in the camera “Settings” menu.

The following guide to choosing the correct ISO number is based on classic rules of photography:

  • ISO 100 – Bright or reflected sunlight.
  • ISO 200 – Overcast or heavy shade.
  • ISO 200 or 400 – Late afternoon, dusk or early morning, depending on the effect you want.
  • ISO 800+ or flash – Indoor and darker environments.

ISO affects the amount of light the camera sees. In both digital and film photography, light is a primary key to image quality. ISO is one of three settings that affect the way the camera interprets light. The other two are shutter speed and aperture (f-stop).

Shutter Speed
Refers to the amount of time the camera’s aperture remains open when you press the shoot button.
Refers to the size of the aperture.

In most point and shoot cameras, manual control of shutter speed and f-stop is not possible.

In film cameras, ISO is controlled by the photographer based on the type of film loaded into the camera, which the photographer determines according to the lighting situation.

In digital cameras, obviously, there is no film, so, if you stick with automated ISO, the camera may misinterpret the lighting situation – by reading a shadow or bright spot incorrectly, for example – then generate settings that compromise focus.

In a low light situation, such as dusk, the camera may auto-select a long shutter speed to compensate for the lack of light. The long speed, in turn, may increase the chance that hand-shake will blur focus.

Alternately, the camera may choose a wide aperture to allow more light to enter the camera. A wide aperture decreases focus range, which cause the outlines of the central object, such as a flower, to blur, especially in macro photography.

On the flip side, in very bright sunlight, if the ISO is not pre-selected, the camera may opt for a very high ISO and wide aperture in combination, with a fast shutter speed, creating a light blast effect that essentially obliterates the central object.

By taking control of the ISO, you essentially force the camera to adapt the auto settings for shutter speed and aperture to the correct lighting situation, thus lowering or even eliminating the chance that the camera will erroneously adjust shutter speed and aperture to compensate for light volume (high or low).

Tip: To get the hang of manually controlling ISO, try setting multiple ISOs for a single image to see if one works better than the other in the particular light setting.

Note finally that on my particular smart phone, the camera defaults to “auto ISO” mode when I exit. Thus, I have to reset ISO every time. Be sure to check yours for the same issue.

To find out more about ISO and digital photography in general, check out this website: Digital Photography School.

To see more of Laura’s flower photographs, check out her photo blog at Flowers in Urbia.

About Laura Mauney

Laura Mauney is a writer who thinks she is a photographer. Professionally, she specializes in online marketing, and creating, organizing and managing creative assets and user-friendly information for websites. She is also a mother. Her photo blogs include Flowers in Urbia and Trees in Urbia.

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