Reduce shake, increase depth of field
By Jason Schneider
November 22, 2007
Some compact digital cameras set a higher ISO automatically as part of their anti-shake program, but many do not.
Setting a higher ISO such as 400 or 640 automatically allows the camera to select a faster shutter speed and/or a smaller aperture at any given light level to achieve the correct exposure.
In many cases this will provide the unbeatable combination of a fast, hand-holdable, shake-effect-minimizing shutter speed and an aperture that's at or near the optimum.
To illustrate how ISO affects sharpness--for good and for bad, we shot the following handheld image at ISO 100, 400, and 1600. 100 percent details at each ISO, below right, tell the story. Photo by Mason Resnick; Camera: Canon Powershot SD1000 Digital Elph.
What about setting an even higher ISO such as 1600 or 3200? While some cameras perform reasonably well at ISO settings in the 1000-1600 range, there is some loss in image quality at the highest ISO settings--digital grain. This is especially the case with compact cameras.
|ISO 100 detail: At 1/25 sec, most photographers will get similarly shaky hand-held results. ISO 400 detail: At 1/100 sec, shot is reasonably sharp.ISO 1600 detail: Fast shutter speed produces sharp image--but look at all of that grain!
Before shooting any important pictures at an ISO above 400 or 640, take a few test shots at the 800, 1000, 1250, and 1600 settings with your camera, and make enlargements or carefully examine the images on your computer screen.
Only you can decide at which point the benefits of setting a higher ISO are outweighed by the overall loss of image quality at higher ISO settings.
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