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What is ISO? ISO Has NOTHING To Do With Exposure!
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Sep 9, 2021 09:58:29   #
Racmanaz Loc: In my bedroom why?
 
Wow, I still learn something new everyday!



https://www.youtube.com/watch?v=ubv-Es_Enio

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Sep 9, 2021 10:17:01   #
Longshadow Loc: Audubon, PA, United States
 
Best explanation ever!

But he'll never convince hardliners.....
People simply see the total/final result of the whole process, part one (the exposure) plus part two (the camera processing).
All three affect the final result, but not the same way.

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Sep 9, 2021 11:36:03   #
Ysarex
 
Racmanaz wrote:
Wow, I still learn something new everyday!



https://www.youtube.com/watch?v=ubv-Es_Enio

It's not nearly the worst -- there's some helpful stuff in there but he basically get's it wrong. He doesn't understand ISO.

First of all there's the attempt-at-shock-value title claiming that ISO has NOTHING to do with exposure. Of course it does. ISO is very closely related to exposure. It is not technically an exposure determinant that affects how much light reaches the sensor, but that doesn't mean it has NOTHING to do with exposure.

He makes one of the more common errors and defines ISO by the most common way in which ISO is implemented. When he shakes the ice tray of water he defines ISO as amplification to the analog sensor signal. That's a common way is which ISO is applied, that's not what ISO is and that definition will get him into trouble especially with his Fuji cameras. In fact it does in another video he's created about Fuji's DR setting where his mistakes are much more severe and derive from his root misunderstanding of ISO.

ISO is a standard methodology for determining the lightness in the camera output JPEG that results from a measured exposure of the camera sensor. The camera manufacturer is free to implement that as they see fit as long as they produce the specified end result.

These short videos make it really hard to address a topic without cutting corners, leaving out important details, and often adding to the confusion. Again to his credit he's better than many out there but he's not getting it right.

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Sep 10, 2021 04:08:13   #
selmslie Loc: Fernandina Beach, FL, USA
 
There are many ways to describe how all of this works. Although it correctly pointed out that exposure is only the result of aperture and shutter speed, the presentation was a bit silly, especially the ice tray part.
Ysarex wrote:
... ISO is a standard methodology for determining the lightness in the camera output JPEG that results from a measured exposure of the camera sensor. ....

Before it gets to the JPEG the charge on the sensor has to get converted to raw values regardless of whether you save a raw file. Those raw values can then get converted to an output JPEG unless you don't save a JPEG in the camera.

If you increase the ISO the raw values are increased - up to the point where they reach the raw file limit where they can no longer increase. More exposure or a higher ISO and the raw highlights will be blown.

At the highest possible raw value the JPEG will also be at its upper limit for brightness. The JPEG cannot get any brighter.

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Sep 10, 2021 05:37:35   #
nison777 Loc: illinois u.s.a.
 
That's why i hate these u tube things...
Most of them are all the same soap box stuff...
I feel bad for those looking for actual information...

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Sep 10, 2021 09:28:59   #
Longshadow Loc: Audubon, PA, United States
 
nison777 wrote:
That's why i hate these u tube things...
Most of them are all the same soap box stuff...
I feel bad for those looking for actual information...

But he's right you know.
(ice trays were not needed.)

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Sep 10, 2021 09:38:06   #
Ysarex
 
selmslie wrote:
There are many ways to describe how all of this works. Although it correctly pointed out that exposure is only the result of aperture and shutter speed, the presentation was a bit silly, especially the ice tray part.

Before it gets to the JPEG the charge on the sensor has to get converted to raw values regardless of whether you save a raw file. Those raw values can then get converted to an output JPEG unless you don't save a JPEG in the camera.

If you increase the ISO the raw values are increased - up to the point where they reach the raw file limit where they can no longer increase.
There are many ways to describe how all of this wo... (show quote)

That is most commonly the case but it is not required in order to implement ISO and there are cameras and various functions in different cameras that implement an ISO increase without increasing the raw values so we can't make that statement without qualification or use that fact as a defining characteristic of ISO which is an error the video author makes.
selmslie wrote:
More exposure or a higher ISO and the raw highlights will be blown.

At the highest possible raw value the JPEG will also be at its upper limit for brightness. The JPEG cannot get any brighter.

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Sep 10, 2021 09:39:41   #
davidrb Loc: Hangar i13
 
Utube has NEVER been associated with truth or honesty. Whatever gave you the idea it did? Children with video cameras do NOT make an honest association. Try someone with authority.

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Sep 10, 2021 09:48:40   #
whfowle Loc: Tampa first, now Albuquerque
 
In photography, ISO is part of the triangle of exposure for digital cameras: shutter speed, aperture opening, and sensitivity of the sensor. But ISO is a standard measurement that is controlled by the International Standards Organization (ISO). Back in the film days, we called it ASA, which is also derived from a standard of the time. It stood for American Standards Association. The value of the two is roughly the same between ISO and ASA. ASA was an American standard and ISO is an international standard. There is a third standard that was common in Europe during the film days called DIN. It comes from Germany. (Deutsche Industrie Norm) With the rise of international standards, ASA and DIN went out of favor and were replaced by ISO. Without universal standards, technology would be a nightmare for the consumer and would slow progress to a crawl.

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Sep 10, 2021 10:00:38   #
Longshadow Loc: Audubon, PA, United States
 
whfowle wrote:
In photography, ISO is part of the triangle of exposure for digital cameras: shutter speed, aperture opening, and sensitivity of the sensor. ...
...
...

More true with film than digital, but still true for both.
Film had ONE exposure "process" to create the final (latent) image on the film. All three parts of the triangle were in that process.
Digital has a two part process to create the final image, the exposure itself and the conversion of the data to an image file. Only aperture and shutter speed control the AMOUNT of light hitting the sensor. ISO is incorporated in the second part.
But all three are still involved in creating the FINAL PRODUCT with digital.

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Sep 10, 2021 11:21:29   #
selmslie Loc: Fernandina Beach, FL, USA
 
Ysarex wrote:
That is most commonly the case but it is not required in order to implement ISO and there are cameras and various functions in different cameras that implement an ISO increase without increasing the raw values so we can't make that statement without qualification or use that fact as a defining characteristic of ISO which is an error the video author makes..

That's not just the most common case. It's the way that all cameras create the default JPEG.

In-camera processing to create a non-standard JPEG does not "implement an ISO increase". It simply creates a different JPEG. You can also take the original raw file and use in-camera editing to produce many different JPEG versions. But that's all post processing, it's not implementing ISO differently.

Moving the Exposure slider in your raw editor does not change the exposure either. It is a misuse of the term that has become common.

Anyone with a clear understanding of the principles would skip the in-camera processing and do all of the manipulations on the computer where it is easier.

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Sep 10, 2021 11:23:15   #
rmalarz Loc: Tempe, Arizona
 
I've known this for some years. Exposure is simply how much light and is independent of the involvement of any photo-sensitive material.

I've also never been a huge fan of the "Exposure Triangle".
--Bob
Racmanaz wrote:
Wow, I still learn something new everyday!



https://www.youtube.com/watch?v=ubv-Es_Enio

Reply
Sep 10, 2021 11:24:40   #
srt101fan
 
davidrb wrote:
Utube has NEVER been associated with truth or honesty. Whatever gave you the idea it did? Children with video cameras do NOT make an honest association. Try someone with authority.


YouTube is much more than "Children with video cameras"!

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Sep 10, 2021 11:25:24   #
rmalarz Loc: Tempe, Arizona
 
You're correct about the hardliners. However, add to that those who just like to argue.
--Bob
Longshadow wrote:
Best explanation ever!

But he'll never convince hardliners.....
People simply see the total/final result of the whole process, part one (the exposure) plus part two (the camera processing).
All three affect the final result, but not the same way.

Reply
Sep 10, 2021 11:30:14   #
srt101fan
 
whfowle wrote:
In photography, ISO is part of the triangle of exposure for digital cameras: shutter speed, aperture opening, and sensitivity of the sensor. But ISO is a standard measurement that is controlled by the International Standards Organization (ISO). Back in the film days, we called it ASA, which is also derived from a standard of the time. It stood for American Standards Association. The value of the two is roughly the same between ISO and ASA. ASA was an American standard and ISO is an international standard. There is a third standard that was common in Europe during the film days called DIN. It comes from Germany. (Deutsche Industrie Norm) With the rise of international standards, ASA and DIN went out of favor and were replaced by ISO. Without universal standards, technology would be a nightmare for the consumer and would slow progress to a crawl.
In photography, ISO is part of the triangle of exp... (show quote)


I'm not an expert, but my understanding, based on comments by the experts, is that ISO has nothing to do with sensor sensitivity.

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