Difference between ISO 100 pushed 6 stops and ISO 6400?

[Iliah Borg]

And yet you can disagree about the necessity to interrelate gain and amplification?

Could you please specify what gain is it?

The ratio of input to output.

Conversion gain? V/PGA gain? Some other?

The gain that's necessary to perform amplification. Just wondering what form of amplification doesn't include a difference between input and output. No one wants to discuss actual operative differences when asked, so maybe we can get the semantics settled.

Conversion gain is not about difference, not about amplification, it is conversion of number of electrons to voltage (µV/e- is how such gain is often cited), or to data numbers (DN/e-).

You may know Albert Theuwissen's blog, http://harvestimaging.com/blog/

Conversion gain is about difference,

When my neighbor has a huge crop of apples, while I have oranges, and we establish the conversion as 2 apples per 1 orange, is it about the difference?

Conversion gain is the reciprocal of capacitance at the pixel (primary sense node, often called "floating diffusion", FD), thus it is intrinsic pixel property.

And it matters because at some point you run out of oranges to exchange for his apples. If you didn't, what would be the point of iso settings and worrying about highlights.

The point of amplification is to optimize the conditions for ADC to achieve accurate measurements. When I have a very good ADC providing low error and high linearity across a wide range of reverence voltages, I skip PGA/VGA altogether, I use programmed reference for the ADC instead. Or I can use a combination.

Please have a look at this: https://www.dpreview.com/forums/post/60752961

I would guess that few people here have an idea that an ADC has a reference that can be changed.

Can I say "second input"?

 

[JDC1958]

ISO as it relates to the camera setting is known as standard output sensitivity, also known as SOS. REI, recommended exposure index means the same thing.

No, it doesn't 'mean the same thing'. Before making such incorrect statements, I would advise actually reading the ISO standard,

In a nutshell, set your camera dial to ISO 100 and you have in effect set it to both SOS 100 and REI 100. I find it funny that they use the words exposure and sensitivity in the definitions; yet there are those who argue that changing the ISO camera dial impacts neither.

I find it funny that people who have clearly not read the ISO standard would lay down the law about what it means.

The term ins 'Standard Output Sensitivity'. It means the sensitivity of the output to exposure - you cannot separate the words 'output' and 'sensitivity'.

 

[Iliah Borg]

ISO as it relates to the camera setting is known as standard output sensitivity, also known as SOS. REI, recommended exposure index means the same thing.

No, it doesn't 'mean the same thing'. Before making such incorrect statements, I would advise actually reading the ISO standard,

In a nutshell, set your camera dial to ISO 100 and you have in effect set it to both SOS 100 and REI 100. I find it funny that they use the words exposure and sensitivity in the definitions; yet there are those who argue that changing the ISO camera dial impacts neither.

I find it funny that people who have clearly not read the ISO standard would lay down the law about what it means.

The term ins 'Standard Output Sensitivity'. It means the sensitivity of the output to exposure - you cannot separate the words 'output' and 'sensitivity'.

--
Tinkety tonk old fruit, & down with the Nazis!
Bob

REI is also what the camera manufacturer recommends and not what the ISO as a standard recommends ( SOS).

And you know that without actually reading the ISO standard, based on "common sense"?

--
Common sense is common knowledge; not everyone's common knowledge is the same.

--
http://www.libraw.org/

 

[JDC1958]

ISO as it relates to the camera setting is known as standard output sensitivity, also known as SOS. REI, recommended exposure index means the same thing.

No, it doesn't 'mean the same thing'. Before making such incorrect statements, I would advise actually reading the ISO standard,

In a nutshell, set your camera dial to ISO 100 and you have in effect set it to both SOS 100 and REI 100. I find it funny that they use the words exposure and sensitivity in the definitions; yet there are those who argue that changing the ISO camera dial impacts neither.

I find it funny that people who have clearly not read the ISO standard would lay down the law about what it means.

The term ins 'Standard Output Sensitivity'. It means the sensitivity of the output to exposure - you cannot separate the words 'output' and 'sensitivity'.

--
Tinkety tonk old fruit, & down with the Nazis!
Bob

REI is also what the camera manufacturer recommends and not what the ISO as a standard recommends ( SOS).

And you know that without actually reading the ISO standard, based on "common sense"?

--
Common sense is common knowledge; not everyone's common knowledge is the same.

--
http://www.libraw.org/

I know that from other sources. If you would like to see a common sense thread on the material; which by the way never mandates how the cameras circuitry processes to a certain ISO here it is:

Loading…

www.openphotographyforums.com

--
Common sense is common knowledge; not everyone's common knowledge is the same.

 

[confused circle]

what would be the point of iso settings...

The point of amplification is to...

As I said, ISO is not amplification.

C'mon guys.

 

[bobn2]

ISO as it relates to the camera setting is known as standard output sensitivity, also known as SOS. REI, recommended exposure index means the same thing.

No, it doesn't 'mean the same thing'. Before making such incorrect statements, I would advise actually reading the ISO standard,

In a nutshell, set your camera dial to ISO 100 and you have in effect set it to both SOS 100 and REI 100. I find it funny that they use the words exposure and sensitivity in the definitions; yet there are those who argue that changing the ISO camera dial impacts neither.

I find it funny that people who have clearly not read the ISO standard would lay down the law about what it means.

The term ins 'Standard Output Sensitivity'. It means the sensitivity of the output to exposure - you cannot separate the words 'output' and 'sensitivity'.

 

[beatboxa]

I'm still amazed that so many people who clearly know very little about this fight so hard to persist in this faulty 'amplification' metaphor.

Here's the simplified view I like to use, since a picture is worth a thousand words:



Depending on the camera's implementation, ISO setting can trigger any one path; or any combination of those paths.

ISO does not describe anything to do with the path--only the output at predefined input & output values (or difference between input & output).

So...

• Will ISO change amplification? Potentially.
• Will ISO alter processing? Potentially.
• Will ISO simply digitally scale? Potentially.
• Will ISO change amplification, processing, and scaling, together, all at once?
  Potentially.

And...

• Can you say that ISO always changes amplification? No.
• Can you say that ISO always changes processing? No.
• Can you say that ISO always changes digital scaling? No.

Most cameras automatically attempt to optimize the path for a middle grey output in a pre-defined JPEG rendering style. The results are relevant to ISO. How it get the results is irrelevant to ISO.

In other words, this entire conversation trying to generically link ISO to amplification is a pointless exercise because there is no universal correlation.

So finally...

• Can you get the same results changing ISO setting vs processing & scaling?
  Depends.
• Can you make a universal rule?
  No.
• What should you call this difference between input & output?
  I don't know. Amplification? Scaling? Neither is technically accurate.
  Maybe "pushed." Or "rendered." I personally don't care as long as it makes sense in context.
  Or maybe we go with just "ISO" and stop trying to come up with imprecise synonyms that may not exist. Even though ISO is not measured by manufacturers against raw, it is recorded with the raw (even if it's just a tag for digital scaling). So let's keep things simple.
  "Here's a raw image. I exposed at 1/250 and F/4 on a full frame. ISO 800."
  What does that mean? Different things on different cameras. So cross reference that information with the camera & any camera-specific data points to sort out what that means if you want. Let's not try to define universal terms that won't exist.

When you set an ISO, you're effectively telling the camera "This is my expected level of output brightness. Please optimize middle grey in this image for me."

When you lower the ISO, you're telling the camera "I want to optimize for highlights."

When you raise the ISO, you're telling the camera "I want to optimize for shadows."



Bobn2: thread limit reached, but I think you meant "precision" (ie. scaling) not "accuracy" in your multimeter analogy here . That's primarily how I use mine.

"Process" is an umbrella term which can be further reduced, and there is no cleaner way I can immediately think of to illustrate the process. For example, software requires hardware. Each step could involve scaling, but not every step involves digital scaling, etc. And that's why it's explicitly a "simplified" view that shows that there is no 1:1 with the semantics being used.

 

[bobn2]

what would be the point of iso settings...

The point of amplification is to...

bobn2 wrote:

As I said, ISO is not amplification.

C'mon guys.

He was reiterating what I said. Either you're just quote mining or your reading comprehension is dreadful. Why do you so much want ISO to be 'amplification'? What is it that is amplified?

bobn2, post: 60753898, member: 1690259"]
I'm still amazed that so many people who clearly know very little about this fight so hard to persist in this faulty 'amplification' metaphor.

Here's the simplified view I like to use, since a picture is worth a thousand words:



View: original size

Depending on the camera's implementation, ISO setting can trigger any one path; or any combination of those paths.
[/QUOTE]
I'm afraid even that is somewhat misleading, in that the steps in image processing are not really 'amplify', 'process', 'scale'. The step is simply 'process'. Depending on 'scaling' applied elsewhere for different reasons the processing may be different.

Those familiar enough with electronics to have used a multimeter might understand it.

As you turn the control knob it scales the reading. That does not affect the quantity being measured nor does it affect the calculations you make as a result of that measurement, it simply affects the accuracy of the measurement.

Bobn2: thread limit reached, but I think you meant "precision" (ie. scaling) not "accuracy" in your multimeter analogy here. That's primarily how I use mine.

Yes, you're right. 'precision is it'. A slightly different case from the application of gain to overcome late-chain noise.

--
Tinkety tonk old fruit, & down with the Nazis!
Bob