ISO. This is an abbreviation that you will heard banded around a lot but perhaps you have no idea what its all about and what those letter stand for!
ISO actually stands for “International Organization for Standardization”. Now that you know that fact Im sure you are none the wiser!
Essentially it is a measure of how sensitive your cameras sensor is to the light that enters through your camera lens and ends up hitting the sensor.
You can adjust the ISO to make the sensor just a bit sensitive or you can make it really really sensitive.
Just a bit sensitive would be an ISO of about 100-200 whereas really really sensitive would be an ISO of say 3200 or higher.
Varying the ISO is used in conjunction with the two other camera settings - aperture and shutter speed. Adjusting these enables the photographer to get the overall correct exposure of the image they are taking.
An ISO of 100 is considered the default or "normal" ISO setting. At this setting your camera sensor is operating at peak performance generating the best quality images.
When you increase the ISO to 200, 400, 800 or 1600 etc you are in effect making the sensor "more sensitive" to light.
Why is this helpful? Well, it helps when you are taking photographs in low light conditions. This is because it takes less light hitting the sensor in order for the sensory to record that light has hit it.
There is a down side though. The higher the ISO, the more sensitive the sensor, the more "grainy" the images will become. This happens because when a particle of light hits a tiny part of the sensor, the sensor is "so sensitive" that some of the surrounding parts of the sensory also fire off. This adds extra unwanted spots or "grain" on the final image. Because of this it is usually best to use the lowest ISO setting that you can.