The ASA standard underwent a major revision in <answer>1960</answer> with ASA PH2.5-<answer>1960</answer>, when the method to determine film speed was refined and previously applied safety factors against under-exposure were abandoned, effectively doubling the nominal speed of many black-and-white negative films. For example, an Ilford HP3 that had been rated at 200 ASA before <answer>1960</answer> was labeled 400 ASA afterwards without any change to the emulsion. Similar changes were applied to the DIN system with DIN 4512:1961-10 and the BS system with BS 1380:1963 in the following years.
In what year were big changes made to the ANSI?
1960