iso

I S O

what does it mean?

International Organization for Standardization

(Curiously, ISO is not meant to be an acronym for anything, it’s allegedly a pun on the Greek prefix “iso-” meaning “same.”)

ISO is equivalent to the old ASA scale (American Standards Association) which has since been discontinued. Film speed

So if u understand film speed u will understand this

Now that we know what the name iso means what does it do

In photography, an ISO number is an indication of the sensitivity of the image sensor, where a higher number indicates higher sensitivity.
Your camera will have range that u can use mine is from 100- 12800

A higher sensitivity allows us to take pictures in low light without using flash. However, this gain usually comes at a price: as we amplify the light signal, we also amplify the noise signal, and high ISO images are usually more "noisy" than low ISO images.
This means the higher the iso u r using the more noise u will have
Remember that an image sensor is still an analog device and it generates its own noise, too! The increased sensitivity allows the image sensor to record more light signal and more noise. The ratio of light signal to noise (S/N ratio) determines the "noise" in your resultant image.



But u can get noise reduction software to help the downside is u may lose detail
also u may have it built in your camera






full – frame camera have a larger sensor and have larger pixels with better light signal to noise ratio so it will be cleaner at high iso's
crop - sensor cameras will not do as well as a full – frame does the same is true for a micro 4/3
ISO sensitivity expresses the speed of photographic negative materials



ISO speed affects the shutter speed / aperture combinations you can use to obtain correct exposure.
Suppose your digital camera's light meter warns you there is not enough light to correctly expose a scene. You could use the on-board flash, but let's suppose again it's not allowed (like in a concert or indoors recital).
You would then need to use a higher ISO. Set on "ISO Auto" mode, your digital camera will automatically select a higher ISO. Otherwise, you can manually select the next higher ISO and see if the increased sensitivity allows you to obtain a correctly exposed picture. If it does, you can now take a correctly exposed picture.
Similarly, if you find the camera is using a shutter speed that is too slow (1/60 sec. and slower) to handhold the camera steady and shake-free (thus resulting in blurred pictures), and you cannot open up the aperture anymore, and you do not have a tripod or other means to hold the camera steady, and you want to capture the action, etc. etc. -- then you might select the next higher ISO which will then allow you to select a faster shutter speed.