The ISO argument

[Fujidave]

This will be the last I post in this thread, for me and me only I don`t actually give a damn about iso as if my images are clean and sharp then I`m well happy.

 

[Ysarex]

OK so were doing this again.

First some parameters:

ISO is an acronym for International Organization of Standards.
ISO - International Organization for Standardization

ISO being standards found in every industry including photography, medicine, government, etc.
ISO9000 is specific to manufacturing.
ISO for photography is a MEASUREMENT for light values. Ergo: STANDARDS.


ISO in film is wholly different for ISO in digital.

There are in fact close similarities, but an understanding of how they are different can be helpful.

They represent the same thing... MEASUREMENT OF LIGHT.

The arguments recently made on ISO (in regards to photography) is mostly based on the arguments made by individuals who want to talk.

The arguments are akin to red cars are faster.

Its nonsensical.

Well the OP in the previous thread was nonsensical -- it's not nonsensical to understand ISO.

But for the sake of argument, the argument of itself is based no the ability to modify the exposure based on modifying aspects of a program to achieve the same results.

Now that's nonsensical. For starters you can't modify exposure after the fact. That's one of the reasons why it's important to understand what exposure is.

ironically, the actions taken though digital and electronic in nature is the same as taken when one over or under exposes silver paper under an enlarger. Achieving the same results.

Speechless.

Joe

Its all a matter of understanding what exposure, light intensity and value are.

 

[Ysarex]

lets go back to the core of this whole ISO argument:
The SENSITIVITY of the capture medium (film or digital) to the light.

The original DIN numbers and then ASA were based on and intended to make a STANDARD for the sensitivity of film.

That sensitivity is based wholly on the size of the silver halide crystals. The larger the crystals, the faster the film.
But it also meant grainier film.

In digital its not size as it is the ability to record the light intensity striking the pixels as based on a mathematical computation.

In digital the sensor responds to the light striking it (photons) by generating a scaled response (electrons) which is then read as an analog voltage signal from the sensor. In most cameras when the sensor must be exposed to less than optimum light intensity ISO engages an amplifier that boosts the analog voltage. That is not a mathematical computation.

The who intent of the ASA/DIN/ISO number was to make UNIFORM the ability to know what the sensitivity was of the film and the appropriate scale to set one's aperture and shutter speed to.

In digital the faster the ISO (ergo 125 v 1000) typically means more "noise" or pixles that infer the light intensity differently from one setting to another.
This can all be changed later in post processing, but it has essentially the same effect and "grainy" film.

It most certainly can not all be changed later in post processing. ISO makes hard and permanent changes to the data recorded by the sensor.

The ISO number for film was standardized for good reason. Because those rules DO NOT apply to digital, the numbers become arbitrary and defined by the manufacturer.

Nonsense. All the current manufacturers of digital cameras adhere to the current ISO standard and supply appropriate notice in the EXIF data with the image. No camera manufacturer is defining their own arbitrary ISO standard.

Joe

But typically is in close proximity to film so that photographers have a basis to work from.

 

[Ysarex]

I put one over the other in PS and set the layer properties as 'difference'
the difference is more visible on screen (obviously)

View attachment 171057

Two different photos taken in sequence and processed separately from two different raw files -- Damn! I did an amazing job of processing them to be alike.

Joe

 

[Derrel]

I was unaware that "the other thread" had been locked at the 12-page stage.

 

[Ysarex]

[>>SNIP>>>look at these two photos; both the same exposure 1/6 sec. f/4 but one at ISO 1000 and the other at ISO 125. See the difference?

View attachment 171044 View attachment 171045

Joe

The two photos look quite similar to me.

Could you elucidate on the importance of using ISO 125 as opposed to ISO 1,000?

Sorry, I had to go out earlier and didn't have time.

Both photos were taken with the same camera (Canon G7xmkii). The exposure was determined for the ISO 1000 shot and set manually. Then the ISO was dropped back to base (125) and the same manual exposure was taken -- that's important: same exposure. Both raw files were processed to produce the same brightness final image. The G7 has a new ISO invariant sensor with only a .3EV variance over the ISO scale: Shadow Improvement of Photographic Dynamic Range versus ISO Setting
That means there should be no apparent advantage in read noise suppression from the ISO 1000 analog amplification as compared with digitally scaling the image. Exposure then is the only real determinant of IQ and since the exposure was the same for both I should be able to process them to look the same.

Joe

 

[Ysarex]

I was unaware that "the other thread" had been locked at the 12-page stage.

Yep, let's not do that again....

Joe

 

[vintagesnaps]

C'mon, keep up Derrel!! lol

Let's see, 2 pages in 5 hours, that would put us at 12 pages by what time tomorrow...?? nm I'm giving myself a headache.

 

[Derrel]

I was unaware that "the other thread" had been locked at the 12-page stage.

Yep, let's not do that again....

Joe

"The ISO argument."
I guess my brain made a subconscious connection.

 

[Ysarex]

I was unaware that "the other thread" had been locked at the 12-page stage.

Yep, let's not do that again....

Joe

"The ISO argument."
I guess my brain made a subconscious connection.

I believe you made the intended connection -- OP said he'd been following it. It is unfortunately a Sisyphean endeavor.

Joe

 

[vintagesnaps]

OK, 3 pages in five hours...


Edit - I confess, I had to look that one up, my LOL was added later...

 

[Ysarex]

Please train me I did notice a highlight on the jars in one of them.

Excellent! You have the best trained eye then. The exposure that was set was determined to place diffuse highlights at ISO 1000. That means specular highlights would be ISO clipped in that raw file and indeed they are. But the ISO 125 shot did not ISO clip those specular highlights and so they retained tone/detail. I deliberately pushed the specular highlights toward clipping in the ISO 125 shot so as not to give it away but I held back enough to leave a clue. One of the real hard effects of raising ISO is an overall loss of DR due to ISO clipping. Avoiding that in certain circumstances is one of the reasons for taking advantage of an ISO invariant sensor.

Joe

 

[Derrel]

SNIP> an ISO invariant sensor.

Joe

SEE: ISO Invariance: What it is, and which cameras are ISO-less

 

[DigiFilm]

https://i.imgflip.com/vspvw.jpg

 

[Ysarex]

https://i.imgflip.com/vspvw.jpg

Yep, walked along Berra Park this morning: Extra Tourists this week

Joe