I’d say 90 percent of the photographers I hear talking about ISO pronounce it like it’s an acronym, as in I.S.O. It’s not.
I, S and O do happen to be letters in the name of the organization which is the International Organization for Standardization, but obviously that would be I.O.S. if you were to use an acronym. The the term ISO is actually derived from a Greek word meaning equal, isos.
The fact is that ISO is not just something related to photography, but has published more than 20,500 international standards and related documents, covering almost every industry, from technology, to food safety, to agriculture and healthcare.
Here’s what the actual organization has to say about it on their website.
Because ‘International Organization for Standardization’ would have different acronyms in different languages (IOS in English, OIN in French for Organisation internationale de normalisation), our founders decided to give it the short form ISO. ISO is derived from the Greek isos, meaning equal. Whatever the country, whatever the language, we are always ISO.
One added benefit to pronouncing ISO, ‘eye so’ is it’s easier to say than I. S. O. so c’mon, especially you pros, and start saying it right. Mkay? Thanks.