gwilliams6

As a Professor of Photography at a state university, and with my Masters Degree in Digital Photography, this is what I teach my students:

For digital photography, ISO refers to the sensitivity of the camera's sensor. The ISO setting is one of three elements used to control exposure; the other two are aperture and shutter speed. ISO originally referred to the sensitivity of film—it's "light gathering" ability. But in digital photography ISO is the amount of sensitivity of the camera's sensor to light.

Changing the sensitivity of the camera's sensor to more or less sensitivity to light by changing the ISO, gives ISO settings an equal and reciprocal part in the Exposure Triangle along with aperture and shutter speed settings.

Adorama TV's Mark Wallace has easy to understand youtube videos on the Exposure Triangle, here is the basic one.
https://www.youtube.com/watch?v=3eVjUrY9a9c

Cheers and best to you all.

JohnSwanda Loc: San Francisco

There is an organization, the International Organization for Standardization, which sets standards for many things, including the light sensitivity of film and digital sensors. But ISO is not an acronym for that organization, since it would be a different acronym in different languages around the world. So they settled on ISO, based on the Greek word isos, so it would be the same in all languages.

Bill_de Loc: US

It's about time somebody came up with a sensible answer!

Considering this thread is a year and half old, may I add, "It took you long enough!"

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gwilliams6

Thanks, LOL,

I admit I do miss seeing and answering all UHH threads. I try to have a live outside of UHH too, LOL

Cheers and best to you all.

trapper1 Loc: Southside Virginia

Thank you for the table. It is very helpful to us newbies to see the relationship. Thanks again.

Trapper1

jcboy3

I am surprised that you are a Professor of Photography and you make this statement. It contradicts the technical definition of exposure and ignores such concepts as ISO invariance and dual gain ISO.

Exposure is the amount of light that reaches the sensor; strictly controlled by aperture and shutter speed. ISO controls the brightness of the resulting image, and is used in automatic exposure modes to produce a change in aperture and/or shutter speed. Aperture also affects the image depth of field. Shutter speed affects motion blur due to subject motion as well as camera motion. ISO has a loose relationship with image noise; more so if the camera is producing JPG output, less so if the camera is producing RAW output.

Note also, that ISO still does refer to sensitivity of film. Film ISO and Digital ISO are two different standards, covered by two different standards documents, and while conceptually similar, they are not the same thing.