Chapter V. Understanding ISO

Understanding ISO

The ISO setting on a compact camera is one of the most important settings. This setting can affect the sharpness of your pictures as well as depth-of-field and image quality. I say can rather than does because lighting conditions come into play with image quality, too.

In this chapter we'll take a look at this all-important and often overlooked camera setting.

For now, just know that when you set the ISO, you are basically (not technically) changing the camera sensor's sensitivity to light. As the ISO increases, so does the sensor's sensitivity. So you might think that a high ISO setting is always best.

Understanding ISO

Bright Light and Low Light Settings

My basic ISO rule is to always use the lowest possible practical ISO setting for the existing lighting conditions. In bright light, I shoot at ISO 100. In low light, I start with an ISO setting of 200. If that low-light setting does not let me shoot at a fast enough shutter speed for a sharp shot, I boost the ISO to 400. If that does not work, I use a tripod to steady my camera during a long exposure.

Above ISO 400, images from most compact cameras, including mine, get a bit grainy. The higher the ISO, the more grain (digital noise) you get in your pictures.

As mentioned earlier, digital noise shows up mostly in the shadow areas. ...

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