Jul 14, 2011

Camera ISO - Sensitivity Towards Light

Camera ISO refers to the camera sensor’s sensitivity towards the light. Normally, we can see ISO100, ISO200, ISO400, ISO640, ISO800 and so on. Light sensitivity increase when the number increase. The higher the sensitivity, the less light is needed to make an exposure. It is very helpful if we are able to control the ISO setting especially during indoor or night shot without flash.

ISO Values For Different Atmosphere
ISO 100 and lower - Excellent quality for brightly lit places, such as in bright sunlight outside. Allows for lots of detail and great image quality.
ISO 200 - Should be generally be used on dull days such as overcast and cloudy, only a tiny bit of noise.
ISO 400 - Great for indoor photography for flash and no flash – best use for high speed photography – but noise can be seen.
ISO 800+ Only really used effectively on high quality digital SLR cameras, most shots taken like this with a small compact camera will look extremely noisy.

How ISO Helps?
i. Increasing Shutter Speed
Higher ISO settings are generally used in darker situations to get faster shutter speeds. The higher the sensitivity, the less light is needed to make an exposure. Hence, the shutter speed can be increased through increasing ISO value. Appropriate shutter speed allows you to capture the specific moment at the right time without affecting much the image quality.

ii. Reducing Blur For Indoor or Night Shots
We always face insufficient light problem when taking indoor or night shots (without external flash support). Blur occurs in the picture due to the slow shutter speed under low ISO value. Through increasing ISO value, we can get faster shutter speed, and this will directly reduce the probability of image blur.

Disadvantage of High ISO – Creating Noise (Little White Dots)
If we are using very high ISO such as ISO3200 during indoor or night, it helps to increase shutter speed, however the picture quality will be affected because of the noise even though there is noise reduction function in the camera. Hence, ISO value shouldn’t exceed ISO1600 under active noise reduction function.
Noise (White Dots) Occurs When Using Very High ISO Value

* Please note that light painting or car trail photography use lowest ISO in order to create long exposure (slow shutter speed) to capture the long moment and star effect from the light.

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