Samsung Galaxy NX500 Camera User Manual (en)

Concepts in Photography
ISO sensitivity
The exposure of an image is determined by the sensitivity of the camera to 
light. This sensitivity is measured by a set of international film standards, 
known as ISO standards. On digital cameras, this sensitivity rating is used 
to indicate the light sensitivity of the digital sensor that captures the 
ISO sensitivity doubles as the ISO number doubles. For example, an ISO 
200 setting is capable of capturing images at twice the speed of an ISO 
100 setting. However, higher ISO settings can result in “noise“—small 
specks, spots, and other phenomena in a photo that give the shot a noisy 
or dirty appearance. As a general rule, it is best to use a low ISO setting 
to prevent noise in your photos, unless you are shooting in darkened 
environments or at night.
A photo captured with a low ISO setting. 
The photo is clear.
The same shot captured with a high ISO 
setting. The photo is grainy.
Because a low ISO setting means the camera will be less sensitive to light, 
you need more light to have an optimal exposure. When using a low ISO 
setting, open the aperture more or reduce the shutter speed to allow 
more light to enter the camera. For example, on a sunny day when light 
is abundant, a low ISO setting does not require a slow shutter speed. 
However, in a dark place or at night, a low ISO setting will result in a blurry 
photo. To compensate for the lower light level, you should increase the ISO 
setting by a moderate amount.
A photo captured with a tripod and a high 
ISO setting.
A blurred photo captured by a camera.