Digital ISO: Today I came upon an article explaining how ISO is determined and measured. It is the best article I have ever read on the subject.

Preachdude Loc: Geneva, OH

Today I came upon an article explaining how ISO is determined and measured. It is the best article I have ever read on the subject.

http://dpanswers.com/content/tech_iso.php

For me, this explains why, with a few of the newest sensors, "auto-ISO" is so much more effective and reliable than the "auto-ISO" setting on older cameras.

rmalarz Loc: Tempe, Arizona

If you really want to read a good book on how ISO is determined, I'd suggest "A memorial volume containing an account of the photographic researches of Ferdinand Hurter & Vero C. Driffield". Like most scientific books, it's rather dry, but very factual and provides an in depth documentation of the area of sensitometry.

There is an online version of the book, but you'll have to do a search for it. I downloaded that version some years ago. I was fortunate in that the university close by has a hard copy of it, as well. Most people using cameras today still don't know how basic exposure is determined.
--Bob

Preachdude wrote:

Today I came upon an article explaining how ISO is determined and measured. It is the best article I have ever read on the subject.

http://dpanswers.com/content/tech_iso.php

For me, this explains why, with a few of the newest sensors, "auto-ISO" is so much more effective and reliable than the "auto-ISO" setting on older cameras.

tbpmusic Loc: LaPorte, Indiana

rmalarz wrote:

........ I was fortunate in that the university close by has a hard copy of it, as well. Most people using cameras today still don't know how basic exposure is determined.
--Bob

Most people today don't know how to use a library..............

rmalarz Loc: Tempe, Arizona

Prior to being able to do research on the internet, I practically lived in the library. In fact, in the last 45+ years, I've lived within 1/2 mile of some sizeable library or another.
--Bob

tbpmusic wrote:

Most people today don't know how to use a library..............

mas24 Loc: Southern CA

Preachdude wrote:

Today I came upon an article explaining how ISO is determined and measured. It is the best article I have ever read on the subject.

http://dpanswers.com/content/tech_iso.php

For me, this explains why, with a few of the newest sensors, "auto-ISO" is so much more effective and reliable than the "auto-ISO" setting on older cameras.

I don't shoot film anymore. But when I borrowed my father's film SLR years, many years ago, it was called ASA, and not ISO as it is today. I noticed on the box of film in your article, ISO is indicated on the box. I don't recall seeing that during my film days of photography. Time surely makes changes. I will read all of your posted article later.

JohnSwanda Loc: San Francisco

mas24 wrote:

I don't shoot film anymore. But when I borrowed my father's film SLR years, many years ago, it was called ASA, and not ISO as it is today. I noticed on the box of film in your article, ISO is indicated on the box. I don't recall seeing that during my film days of photography. Time surely makes changes. I will read all of your posted article later.

The change did happen before digital came along. It was a change from an American organization to an international one, which determines the standards for many other things than film/sensor sensitivity.

mas24 Loc: Southern CA

JohnSwanda wrote:

The change did happen before digital came along. It was a change from an American organization to an international one, which determines the standards for many other things than film/sensor sensitivity.

Thanks for the info. I did not know that until now.