Thursday 7 October 2010

ISO-Low or High

Traditionally ISO's have always been in full stops i.e 100,200,400,800 etc, But now we have 1/3 stops as well so now we have 100,125,160,200,250,320,400 etc, I personally always use full stops but i know others that use the 'in between' ISO's, So say that you are using ISO 400 and feel that you could use a slightly lower ISO and change to 320 thats going to help with image quality right? well not really as the 'in between' ISO's are not real ISO's, What happens is ISO 200 is a real ISO but ISO 250 is an over exposed 200 and 320 is an under exposed 400 and so on and so on, We know that over exposing is good for IQ as in exposing to the right but under exposure is bad for IQ, So in reality ISO 320 can give a grainier image that 400-Food for thought when choosing what ISO to use



  1. I use the full stops and expose to the right so as that's tradition I assume I'm getting old?

  2. Thanks Dave. I only ever use full stops but was unaware of the over and under exposure issues