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CAMERA SENSITIVITY - ISO
Five settings can be selected for camera sensitivity: Auto, 100, 200,
400, and 800; the numerical values are based on an ISO equivalent.
ISO is the standard used to indicate film sensitivity: the higher the
number, the more sensitive the film. See ‘setting the function dial’
section on page 40 to change the ISO setting.
The auto setting automatically adjusts the camera sensitivity to the light conditions
between ISO 100 and 400. When the flash is activated and camera sensitivity is set to
auto, the ISO value is set to ISO 200. When any other setting than auto is used, “ISO”
will appear on the data panel and “ISO” and the set value will be displayed on the
monitors.
Photographers can select a specific sensitivity setting. Like grain in silver-halide film
that increases with speed, noise increases with sensitivity in digital imaging; an ISO
setting of 100 will have the least noise and 800 will have the most noise. A change in
ISO also effects the flash range (p. 79); the higher the ISO, the greater the range.
As the ISO value doubles, the camera sensitivity doubles; changing the ISO between
100 and 200, 200 and 400, or 400 and 800 changes the camera sensitivity by one stop
or 1 Ev (p. 36). A change between 100 and 800 changes the camera sensitivity by a
factor of 8 or three stops. High ISO settings (400, 800) will allow the photographer to
hand hold the camera in low-light conditions without the need of a flash.
When making bulb exposures (p. 92), noise can be more pronounced because of the unusually
long exposure times, especially at 400 and 800 ISO. When making long bulb exposures of 20 to
30 seconds, a camera sensitivity setting of 100 or 200 will produce excellent results. At higher
ISO settings, using shorter exposure times (8 - 16 seconds) will reduce the effect of noise. With
long exposures at high ISO settings, noise from interference may be noticeable.
Camera Notes