srt101fan

No I didn't read it. I'm looking for your definition of ISO as used in digital photography. I didn't think I'd find it there.

But I really don't have time for more replies to your irrelevant comments. Best to you.

JohnSwanda Loc: San Francisco

Here is what Nikon has to say, although the OP won't like it, because they say it is a way to control exposure. ISO and ASA are both organizations which set standards in various fields, in this case the sensitivity of film/sensor to light. ISO is international, which took over from ASA which was American. The standard was the same.

https://www.nikonusa.com/en/learn-and-explore/a/products-and-innovation/iso-control.html

selmslie Loc: Fernandina Beach, FL, USA

In other words you were not interested in learning anything. You were just being rude and confrontational.

I was giving you the benefit of the doubt. I'll know better next time.

srt101fan

Against my better judgment I'll give it one more try and summarize our dialog:

I made the statement that "Digital ISO" is not the same as film ASA, DIN, etc..

You posted that "It is exactly the same."

I asked you nicely for your definitions of the two subjects. You have avoided doing that by wandering into irrelevant weeds.

And you call me rude and unwilling to learn....

selmslie Loc: Fernandina Beach, FL, USA

I provided plenty of evidence to back up my statement.

So why don’t you tell us how digital ISO is different?

Ball is in your court.

srt101fan

Interesting what Nikon says. For whatever reason, they don't subscribe to the long-standing definition of exposure. I'll stick with the "ISO does not change sensor sensitivity" crowd until I see a more compelling reason to change.

I understand the role of the ISO and ASA standards. I'm more interested in what ISO means in the context of someone picking up a digital camera and setting up the controls to get a good photo. In that context, I think the "standards" aspects of ISO are immaterial, irrelevant and, I think, of no interest to most photographers. I think of it as a camera control/setting, not a standard or a rating as used in film. That's why I don't think digital ISO and ASA are the same, and that's why I asked selmslie for his definitions

selmslie Loc: Fernandina Beach, FL, USA

ANSI, ASA and ISO standards have been around for nearly 80 years - unchanged. Sunny 16 worked the same in 1943 as is does now for film and digital.

We don't have a film ISO standard and a digital ISO standard. We just have a single ISO standard.

How do you define film ISO differently from digital ISO? You need to explain why you "don't think digital ISO and ASA are the same".

Ysarex Loc: St. Louis

Film -- B&W negative: https://www.iso.org/standard/3580.html
Film -- Color reversal: https://www.iso.org/standard/34533.html
Film -- Color negative: https://www.iso.org/standard/11948.html

Digital still cameras: https://www.iso.org/standard/73758.html

selmslie Loc: Fernandina Beach, FL, USA

Is there a material difference when it comes to metering for exposure?

Do we need four separate light meters?

selmslie Loc: Fernandina Beach, FL, USA

Those were rhetorical questions whose answers are "NO".

When film cameras started to include their own meters there was never a need to identify whether the film was B&W negative, color reversal or color negative. The same light values were used for all three. The different metering methods (average, center weighted, spot, matrix) followed a single standard for manual and auto exposure. Meters were also developed to work with high speed flash and ASA/ISO/DIN was used with all of them.

All of the in-camera metering methods were compatible with hand-held meters - spot, incident or flash - and based on the same standard ISO values.

When digital cameras showed up the same metering methods offered the same suggested exposures at the same ISO settings. Otherwise there would have been a period of chaos as we tried to reconcile any differences. Digital necessarily had to follow the same standards as film cameras.

Although metering methods have been refined over time the only significantly new method offered specifically for digital was highlight weighted matrix metering.

So from a photographer's viewpoint there is really only a single standard for ISO. And Sunny 16 is just as relevant today as it was in 1943. So is the exposure triangle since it allows us to balance ISO against exposure.

Ysarex Loc: St. Louis

Unless you were a photographer in which case you set an EI based on unique characteristics of each medium: https://125px.com/docs/techpubs/kodak/cis185-1996_11.pdf

No. From ISO 12232:2019, Abstract: "This document specifies the method for assigning and reporting ISO speed ratings, ISO speed latitude ratings, standard output sensitivity values, and recommended exposure index values, for digital still cameras." Note that both standard output sensitivity (SOS) values as well as recommended exposure index (REI) values are addressed. Our digital cameras use one or the other and they do not offer the same suggested exposures at the same ISO settings.

Srt101fan asked you a direct question: https://www.uglyhedgehog.com/t-710872-7.html#12551302 You never answered it. Pressed for an answer you became your usual belligerent self and eventually pontificated this ridiculous cluelessness: "We don't have a film ISO standard and a digital ISO standard. We just have a single ISO standard."

Now you're heading off on your usual sophist ranting to justify your error. Yes we do have different ISO standards for film and digital still cameras: https://www.uglyhedgehog.com/t-710872-8.html#12553141

I'm so looking forward to the charts and graphs now -- you are going to have charts and graphs for us right?

selmslie Loc: Fernandina Beach, FL, USA

While I am trying to bring some light and common sense to the question you insist on shedding darkness and confusion. Nothing you are saying makes this easier for anyone else to understand.

All of your other information is just fog - your attempt to complicate a really simple question by making a federal case out of it.

None of what you are offering can improve on the clarity and simplicity of Sunny 16 - 1/ISO @ f/16 (or equivalent) for broad daylight. It's that easy. It works. It has worked for eight decades. It works for all three types of film as well as for digital capture. It's what unifies all four versions of ISO. It's why you can use the same exposure for a given ISO no matter which medium you are using.

Maybe you just don't understand why it works.

Since it works for broad daylight it can work just as easily for any luminance levels (LV). EV=LV at ISO 100. If you change the ISO all you need is to measure the LV and adjust the EV accordingly.

Don't you understand Exposure value? It's not rocket science.

Ysarex Loc: St. Louis

You were asked a simple question: https://www.uglyhedgehog.com/t-710872-7.html#12551302

This was your answer: "We don't have a film ISO standard and a digital ISO standard. We just have a single ISO standard." Maybe you can provide a link for us to that single ISO standard. I'll help you get started. Here's a link to the website for the International Organization for Standardization: https://www.iso.org/home.html

Maybe there's a chart or graph in the standard!

selmslie Loc: Fernandina Beach, FL, USA

I'm not going to engage in another protracted exchange with you.

If you were not too lazy or had any real interest in learning something you would perform your own tests as I have instead of surfing the internet from the comfort of you chair.

If you did your own tests you would realize that I am right about ISO 100 (or any other ISO) working the same for film as for digital. That's why we could use the same meters for all three types of film.

That's also why we didn't need to buy new hand-held reflected light, spot and incident meters when digital came along. The ones we already had would give us the same answer.

Then you would be faced with an insurmountable problem. You would have to admit that I have been right and you have been wrong about whether different ISO standards make any real difference. You are not going to do that because you are who you are.

Bye bye.

Ysarex Loc: St. Louis

As expected you've provided no link to the "We just have a single ISO standard" that you fabricated.

Anyone interested can of course look up the actual standards:
https://www.iso.org/standard/3580.html
https://www.iso.org/standard/34533.html
https://www.iso.org/standard/11948.html

https://www.iso.org/standard/73758.html

And of course their very existence proves that you are full of BS.
So the original question you were asked remains unanswered. https://www.uglyhedgehog.com/t-710872-7.html#12551302 That must mean you really don't know what you were talking about.