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Dynamic Range - Underexposed to avoid High ISO

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John31000

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Hello everyone

I had some questions after looking some informations about dynamic range, iso and so on ...

My camera (olympus em1 mark ii) got a function to see if some area are overexposed or underexposed.

If I'm in bad lighting condition like night outdoor and at 0EV and I doesn't see underexposed area. Can I underexposed to gain some ISO stop right ?

Like i'm at : f 1.7 , ISO 6400, 0EV , SS : 1/10 -> f1.7 , ISO 3200, -1EV, SS : 1/10

In post processing, I can then overexposed by one stop to get the same image as I would have taken if i was at 0EV without losing details if I CANT see "underexposed area" at -1EV ?

I guess the same can be applied for overexposed area ?

Also, if the camera has a very good dynamic range (like some high end FF model) I would guess I can underexposed more than with my olympus ?

Thanks
 
Razor512 said:
We likely will not see true ISO invariance until we reach a point where we get ADCs that can sample the entire analog range of the image sensor directly without the need of an LNA.
Click to expand...
You mean VGA, not LNA. There's always going to be 'amplification' somewhere in the read chain, and if done competently will be low noise.
 
SmilerGrogan said:
It is impossible to make an exposure decision unless you include an assumption about the sensitivity of the sensor.
Click to expand...
And yet photographers do it all the time. You do it all the time. You don't know the sensitivity of the sensor for any camera you use or have used.
Or do you truly believe that you can produce equally perfect photographs on a cloudless day at noon in Mitad del Mundo whether you set your camera at 1/8000 and f32 or 2 hours at f/1.4? Because I’d like to see that. Irrelevant rhetoric. [QUOTE="And please stop misleading people about the term sensitivity. The ISO defines it: [I]photographic sensitivity general term used for numerical values calculated based on the exposure at the focal plane of a DSC which produces a specified DSC image signal level said:
If you don’t like that definition, tough luck, you don’t get to change the rules or slander the work of people like Toru Nagata and Jack Holm just because you and the angry Bob can’t make it fit into your world view.
Click to expand...
But we do get to read the definition properly. Something you might try, if you can.
SmilerGrogan said:
Iliah Borg, post: 63704348, member: 1163177"]
SmilerGrogan, post: 63704348, member: 1163177"]
Yet as the poster above demonstrates, and from other example we’ve seen, there are no ISO invariant cameras. Deliberate underexposure produces unrecoverable problems with digital files.
Click to expand...
You sound like you think that ISO setting is a part of exposure. Is that so?

"Problems" are also produced by dust specs on the lens. A lens resolving not as good as a top-of-the-line one is a "problem". Having a slightly outdated camera is also a "problem". It's not enough to just say "problem". We make decisions, hopefully informed ones; and those decisions quite often involve trade-offs.
Click to expand...
Click to expand...
[/QUOTE]
[/QUOTE]
 
The X-T20's invariance range begins at ISO 800 or just above.

a316ea58191f45c9ada702769add92de.jpg

Do the work. Use your camera to make test images. It's easy; takes five minutes out of your day. I've done it. I've posted the photos demonstrating the invariance of the X-T20 sensor. And the D600/610. And the D500. Neither you nor anybody else has demonstrated otherwise.

--
Bill Ferris Photography
Flagstaff, AZ
 
SmilerGrogan said:
SmilerGrogan said:
SmilerGrogan said:
Yet as the poster above demonstrates, and from other example we’ve seen, there are no ISO invariant cameras. Deliberate underexposure produces unrecoverable problems with digital files.
Click to expand...
You sound like you think that ISO setting is a part of exposure. Is that so?
Click to expand...
SmilerGrogan wrote:

It is impossible to make an exposure decision unless you include an assumption about the sensitivity of the sensor.
Click to expand...
Sensor responsivity is not measured in ISO speed units. Sensor sensitivity is not what you think it is, read https://en.wikipedia.org/wiki/Responsivity

ISO speed is determined based on exposure, and thus it is not an element of exposure. Simple as that.
SmilerGrogan said:
The ISO defines it:

photographic sensitivity
Click to expand...
Get the standard and read it carefully, until it sinks.
SmilerGrogan said:
general term used for numerical values calculated based on the exposure
Click to expand...
Like this: "calculated based on exposure". So, again, how something that is based on exposure is a part of exposure?
 
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bobn2 said:
SmilerGrogan said:
you don’t get to change the rules or slander the work of people like Toru Nagata and Jack Holm just because you and the angry Bob can’t make it fit into your world view.
Click to expand...
But we do get to read the definition properly. Something you might try, if you can.
Click to expand...
Since he dropped Mr. Holm's name,

"The ISO standards for photographic exposure determination specify 5.6 as the ratio of the adopted white luminance to the scene arithmetic mean luminance, and 6.9 as the ratio of the adopted white luminance to the geometric mean luminance. While these values are reasonable ensemble averages, they can vary quite dramatically from scene to scene. The results of an analysis of 126 outdoor scenes:"

White to arithmetic mean ratio, minimum 1.89, maximum 18.6; std. dev. 3.11, ensemble average 5.43 (see Table 1)

I'm not sure he understands the above.

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.

With digital photography, this correlation no longer applies, because it is a simple matter to adjust the darkness or lightness digitally. Some cameras do this automatically, and in camera raw processing applications, the user can make adjustments after the picture is taken. The film exposure mindset is actually a hindrance to the best use of digital capture."
 
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Iliah Borg said:
..
Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.

Higher exposures resulted in denser negatives, and lower exposures resulted in thinner negatives. Most workflows would compensate for negative density when printing. Thus a print from a denser negative would frequently result in print that was just as light/dark as a print from a thinner negative.

The problem with a negative that was too dense/thin was that the tone curve was not optimal, not that the print was too light or dark.

Iliah Borg said:
With digital photography, this correlation no longer applies, because it is a simple matter to adjust the darkness or lightness digitally. Some cameras do this automatically, and in camera raw processing applications, the user can make adjustments after the picture is taken. The film exposure mindset is actually a hindrance to the best use of digital capture."
Click to expand...
When consumers sent their film to the corner photo lab, the machines automatically adjusted for negative density. Darkroom technicians would handle this for high end images.

About the only time I saw lightness differences from variations in negative density was in my contact prints. That's the only time I would use the same settings for printing every frame from a roll. Even with contact prints, I could dodge and burn strips of negatives.

With digital we do see a strong correlation between exposure and image lightness in the situation where the camera is set to produce JPEG images, and is set for a fixed ISO. Personally, I believe that this is due to early digital cameras trying to mimic the film workflow.
 
ThrillaMozilla said:
Bill Ferris said:
On the other hand, I've demonstrated the Nikon D600, D610 and D500 and the Fuji X-T20 to be ISO invariant.
Click to expand...
I don't think any camera is completely ISO-invariant if you do the measurements or look closely. But as a practical matter, some cameras are very close, and for most practical purposes are invariant. Here are some measurements:

http://www.photonstophotos.net/Char...14,Nikon D500_14,Nikon D600_14,Nikon D7200_14

Is the glass half full or half empty?
Click to expand...
For the practical implications I'd look at Shadow Improvement rather than Input-Referred Read Noise.

Of the cameras you chose the D600 is less obvious.

The Nikon Z6 and Z7 are very ISO Invariant once high conversion gain kicks in.
 
Michael Fryd said:
Iliah Borg said:
..

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.
Click to expand...
You are missing something like "best quality" mentioned above.

The purpose of the quotes was to demonstrate what were / are the thoughts of Mr. Holm on ISO speed, the way he uses the term "lightness", and, most of all, his understanding that "the film exposure mindset is actually a hindrance to the best use of digital capture" , - and not for you to argue with him, without even paying attention to what he is actually saying. If you want to argue, the place is a separate thread. But before you start it, pay attention to what is written, and study Mr. Holm's position and his contributions a tad more.
 
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Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
..

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.
Click to expand...
You are missing something like "best quality" mentioned above.
Click to expand...
Yes, when shooting film, hitting the target exposure maximized quality. Generally, you would get the best quality by using a film with a lower speed rating and targeting a higher ISO.

However, there is a difference between "image quality" and the "lightness and darkness of the final print."

If you're going to make the case that photographer's associated exposure with how dark a negative looked, then higher exposures (more light reaching the film) would be associated with darker negatives. Denser negatives look darker.
 
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
..

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.
Click to expand...
You are missing something like "best quality" mentioned above.
Click to expand...
Yes, when shooting film, hitting the target exposure maximized quality. Generally, you would get the best quality by using a film with a lower speed rating and targeting a higher ISO.
Click to expand...
You still don't understand. Try asking questions on PS&T forum.
 
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
..

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.
Click to expand...
You are missing something like "best quality" mentioned above.
Click to expand...
Yes, when shooting film, hitting the target exposure maximized quality. Generally, you would get the best quality by using a film with a lower speed rating and targeting a higher ISO.
Click to expand...
You still don't understand. Try asking questions on PS&T forum.
Click to expand...
I was disputing the claim that there was a "strong correlation" in the mind of film users between exposure and how dark/light the prints looked. That is a separate issue from the quality of the image.
 
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
..

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.
Click to expand...
You are missing something like "best quality" mentioned above.
Click to expand...
Yes, when shooting film, hitting the target exposure maximized quality. Generally, you would get the best quality by using a film with a lower speed rating and targeting a higher ISO.
Click to expand...
You still don't understand. Try asking questions on PS&T forum.
Click to expand...
I was disputing the claim that there was a "strong correlation" in the mind of film users between exposure and how dark/light the prints looked.
Click to expand...
If you are disputing Mr. Holm's observations, e-mail Mr. Holm. But start with reading what he says, because now you are projecting your own thoughts into his words. Here is what the quotes were - notice Mr. Holm didn't even use the word "print".

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.

With digital photography, this correlation no longer applies, because it is a simple matter to adjust the darkness or lightness digitally. Some cameras do this automatically, and in camera raw processing applications, the user can make adjustments after the picture is taken. The film exposure mindset is actually a hindrance to the best use of digital capture."
 
bclaff said:
Of the cameras you chose the D600 is less obvious.

The Nikon Z6 and Z7 are very ISO Invariant once high conversion gain kicks in.
Click to expand...
Just a couple of minor comments.

For the record, I didn't choose the D600. Bill Ferris did. Also, the Z6 and Z7 are no different from most of the other cameras in the link I posted, i.e. invariant as a practical matter, but not completely invariant if you look at read noise.
 
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
..

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.
Click to expand...
You are missing something like "best quality" mentioned above.
Click to expand...
Yes, when shooting film, hitting the target exposure maximized quality. Generally, you would get the best quality by using a film with a lower speed rating and targeting a higher ISO.
Click to expand...
You still don't understand. Try asking questions on PS&T forum.
Click to expand...
I was disputing the claim that there was a "strong correlation" in the mind of film users between exposure and how dark/light the prints looked.
Click to expand...
If you are disputing Mr. Holm's observations, e-mail Mr. Holm. But start with reading what he says, because now you are projecting your own thoughts into his words. Here is what the quotes were - notice Mr. Holm didn't even use the word "print".

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.

With digital photography, this correlation no longer applies, because it is a simple matter to adjust the darkness or lightness digitally. Some cameras do this automatically, and in camera raw processing applications, the user can make adjustments after the picture is taken. The film exposure mindset is actually a hindrance to the best use of digital capture."
Click to expand...
Yes, increased exposure results in a "darker" negative. However most people don't associate increased exposure with a darker result.
 
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
Michael Fryd said:
Iliah Borg said:
..

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.
Click to expand...
In many common film workflows increasing or decreasing exposure did not alter the darkness or lightness of the resulting prints.
Click to expand...
You are missing something like "best quality" mentioned above.
Click to expand...
Yes, when shooting film, hitting the target exposure maximized quality. Generally, you would get the best quality by using a film with a lower speed rating and targeting a higher ISO.
Click to expand...
You still don't understand. Try asking questions on PS&T forum.
Click to expand...
I was disputing the claim that there was a "strong correlation" in the mind of film users between exposure and how dark/light the prints looked.
Click to expand...
If you are disputing Mr. Holm's observations, e-mail Mr. Holm. But start with reading what he says, because now you are projecting your own thoughts into his words. Here is what the quotes were - notice Mr. Holm didn't even use the word "print".

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.

With digital photography, this correlation no longer applies, because it is a simple matter to adjust the darkness or lightness digitally. Some cameras do this automatically, and in camera raw processing applications, the user can make adjustments after the picture is taken. The film exposure mindset is actually a hindrance to the best use of digital capture."
Click to expand...
Yes, increased exposure results in a "darker" negative.
Click to expand...
Where does Mr. Holm say to the contrary? Do you have difficulty processing "if the exposure is incorrect the image formed on the film will be either too dark or too light"?
Michael Fryd said:
However most people don't associate increased exposure with a darker result.
Click to expand...
All he says about the "result" is "the amount of exposure required to produce the best quality images", and that the criteria of the correct exposure for film is often its "darkness/lightness". He notes that this criteria doesn't apply to digital photography.

Enough of this projection already.
 
Last edited:
Iliah Borg said:
bobn2 said:
SmilerGrogan said:
you don’t get to change the rules or slander the work of people like Toru Nagata and Jack Holm just because you and the angry Bob can’t make it fit into your world view.
Click to expand...
But we do get to read the definition properly. Something you might try, if you can.
Click to expand...
Since he dropped Mr. Holm's name,

"The ISO standards for photographic exposure determination specify 5.6 as the ratio of the adopted white luminance to the scene arithmetic mean luminance, and 6.9 as the ratio of the adopted white luminance to the geometric mean luminance. While these values are reasonable ensemble averages, they can vary quite dramatically from scene to scene. The results of an analysis of 126 outdoor scenes:"

White to arithmetic mean ratio, minimum 1.89, maximum 18.6; std. dev. 3.11, ensemble average 5.43 (see Table 1)

I'm not sure he understands the above.

Being a convenor of ISO/TC 42/JWG 20, Joint ISO/TC 42- IEC WG: Digital still cameras, in 2009 Mr. Holm wrote:

"The purpose of the “ISO speed rating” is to specify the amount of exposure required to produce the best quality images. With film capture, this is relatively straightforward – if the exposure is incorrect the image formed on the film will be either too dark or too light. Years of experience with this paradigm have led to a strong correlation in users’ minds between exposure and darkness/lightness.

With digital photography, this correlation no longer applies, because it is a simple matter to adjust the darkness or lightness digitally. Some cameras do this automatically, and in camera raw processing applications, the user can make adjustments after the picture is taken. The film exposure mindset is actually a hindrance to the best use of digital capture."
Click to expand...
Yes, I suspect that our friend Smiler has not realised that his heroes are also masters of the scientific/technical side as well as the creative. Funny how often the two things go together.
 
X-T20 ISO 800



6e69ef5696b74976be836c41ccdf7f1a.jpg



X-T20 ISO 3200



45947ef639944ad2a1d32dec33ba6476.jpg





PS, you will get the same results if you transpose all of the metadata dealing with the state of the camera from the ISO 3200 file to an ISO 800 or ISO 200 file at the binary level (tricking ACR into thinking that it was shot at ISO 3200). It makes no visible difference than the files having their original metadata



The only time you get visual changes with changes to the metadata, is when you mess with the built in lens correction data that fujifilm embeds in the raw files
 
Basically what I am doing is taking raw files from the ISO invariance test and repeating the adjustments that DPreview made

https://www.dpreview.com/reviews/im...ion=full&widget=487&x=0.151173145&y=0.5005349

Then while using those adjustments as a starting point, I then proceed to do other adjustments.

The reason why is because many people stop after doing something like just moving the exposure slider in lightroom 4 or 5 stops and making no other changes, and then when the base ISO image looks about the same as the ISO3200 image, they call the camera ISO invariant.

It is like taking a Nissan GTR and claiming it gear invariant because it can do 55MPH on the highway using 3rd, 4th, 5th, and 6th gear.

Most ISO invariance claim so while never never pushing any of the files to their limits in terms of latitude, thus you get a false sense of invariance.

The only time when you get true invariance on a digital camera, is when you start to enter expanded ISO ranges where the camera is applying purely digital gain at the ADC , at which point, you do not really get any visual difference from cranking up the ISO or using the exposure slider in post in terms of detail and gradients, in the luminance and color channels.
 
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