M10 vs Sony A7RIII - ISO differences

[david strachan]

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ISO means International Standards Organisation. A framework that means consistency, across measurements.

 

A lot of people buy cameras on ISO performance, so if manufacturers make their own standards...seems a bit unfair.

 

If I use a spotmeter, I expect to translate that measurement to the EV and ISO for film or digital, consistently...to get exactly the same exposure, across all cameras.

 

Perhaps it sould be called DISO, meaning for that particular manufacturer...

 

Sure, once you are working your camera, make allowances...because the manufacturers do fudge the ISO values for more sales.

 

I would rather see ISO a set standard across all photographic systems...as originally intended.

 

...

[Chaemono]

See here: https://www.dpreview.com/forums/thread/2838786

 

"...about digital camera ISO determinations . It all depends on which Standard did the manufacturer of a DSLR decided to adhere to , the REI or the SOS and whether the user is creating RAW files or JPG for output. Please read on.

 

ISO 12232:2006 is a document written by the International Organization for Standarization (ISO)

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 . ISO 12232:2006 is applicable to both monochrome and colour digital still cameras.

 

This publication can be obtained from the International Organization for Standarizationhere: 
http://www.iso.org/iso/catalogue_detail.htm?csnumber=37777

 

What follows is an excerpt from it:

 

The ISO 12232:2006 standard

The ISO standard 12232:2006[15] gives digital still camera manufacturers a choice of five different techniques for determining the exposure index rating at each sensitivity setting provided by a particular camera model. Three of the techniques in ISO 12232:2006 are carried over from the 1998 version of the standard, while two new techniques allowing for measurement of JPEG output files are introduced from CIPA DC-004.[16] Depending on the technique selected, the exposure index rating can depend on the sensor sensitivity, the sensor noise, and the appearance of the resulting image. The standard specifies the measurement of light sensitivity of the entire digital camera system and not of individual components such as digital sensors, although Kodak has reported[17] using a variation to characterize the sensitivity of two of their sensors in 2001.

 

The Recommended Exposure Index (REI) technique, new in the 2006 version of the standard, allows the manufacturer to specify a camera model’s EI choices arbitrarily . The choices are based solely on the manufacturer’s opinion of what EI values produce well-exposed sRGB images at the various sensor sensitivity settings. This is the only technique available under the standard for output formats that are not in the sRGB color space. This is also the only technique available under the standard when multi-zone metering (also called pattern metering) is used.

 

The Standard Output Specification (SOS) technique , also new in the 2006 version of the standard, effectively specifies that the average level in the sRGB image must be 18% gray plus or minus 1/3 stop when exposed per the EI with no exposure compensation . Because the output level is measured in the sRGB output from the camera, it is only applicable to sRGB images—typically JPEG—and not to output files in raw image format. It is not applicable when multi-zone metering is used.

 

The CIPA DC-004 standard requires that Japanese manufacturers of digital still cameras use either the REI or SOS techniques. Consequently, the three EI techniques carried over from ISO 12232:1998 are not widely used in recent camera models (approximately 2007 and later) . As those earlier techniques did not allow for measurement from images produced with lossy compression, they cannot be used at all on cameras that produce images only in JPEG format.

 

The saturation-based technique is closely related to the SOS technique, with the sRGB output level being measured at 100% white rather than 18% gray. The saturation-based value is effectively 0.704 times the SOS value .[18] Because the output level is measured in the sRGB output from the camera, it is only applicable to sRGB images—typically TIFF—and not to output files in raw image format. It is not applicable when multi-zone metering is used.

 

The two noise-based techniques have rarely been used for consumer digital still cameras. These techniques specify the highest EI that can be used while still providing either an “excellent” picture or a “usable” picture depending on the technique chosen." 
--

Edited May 5, 2018 by Chaemono

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[mdemeyer]

Great reference, thanks.

[M11 for me]

I must say that it amuses me how worked up some people get about this meaningless nonsense.  . . . . . have been teaching photography for more than 30 years, and will use my cameras any damn way I please. Get off your high horse, junior.

 

Oh, were you teaching that this is all nonsense? And did you make joke of your junior student understanding even less than nonsense? How this all started here: One picture from one camera is darker than the same frame from another camera at the same nominal settings. That is an excellent and very interesting question: Why does that difference occur? Then we see in the DxO database that the M10 behaves differently to most other cameras including Canon and Nikon and the best: Including Leica cameras! What follows here is an unnecessary defense plea from one part of the posters here. A second group thinks that it is all unnecessary discussion and still get fully worked up about something that they consider meaningless. For me the question is very valid and interesting at the same time: Why does the difference in brightness occur. And I am happy to be able to read here very constructive posts from many Leica users here.

Edited May 5, 2018 by Alex U.

[Chaemono]

Great reference, thanks.

 

Thanks. I'm sure the energizer bunnies here were aware of it. But they can't help it, they have to keep going and going. 

[jaapv]

ISO means International Standards Organisation. A framework that means consistency, across measurements.

 

A lot of people buy cameras on ISO performance, so if manufacturers make their own standards...seems a bit unfair.

 

If I use a spotmeter, I expect to translate that measurement to the EV and ISO for film or digital, consistently...to get exactly the same exposure, across all cameras.

 

Perhaps it sould be called DISO, meaning for that particular manufacturer...

 

Sure, once you are working your camera, make allowances...because the manufacturers do fudge the ISO values for more sales.

 

I would rather see ISO a set standard across all photographic systems...as originally intended.

 

...

Well, I'm sure that post #43 clarifies the situation.

[jaapv]

Advertisement (gone after registration)

See here: https://www.dpreview.com/forums/thread/2838786

 

"...about digital camera ISO determinations . It all depends on which Standard did the manufacturer of a DSLR decided to adhere to , the REI or the SOS and whether the user is creating RAW files or JPG for output. Please read on.

 

ISO 12232:2006 is a document written by the International Organization for Standarization (ISO)

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 . ISO 12232:2006 is applicable to both monochrome and colour digital still cameras.

 

This publication can be obtained from the International Organization for Standarizationhere: 

http://www.iso.org/iso/catalogue_detail.htm?csnumber=37777

 

What follows is an excerpt from it:

 

The ISO 12232:2006 standard

The ISO standard 12232:2006[15] gives digital still camera manufacturers a choice of five different techniques for determining the exposure index rating at each sensitivity setting provided by a particular camera model. Three of the techniques in ISO 12232:2006 are carried over from the 1998 version of the standard, while two new techniques allowing for measurement of JPEG output files are introduced from CIPA DC-004.[16] Depending on the technique selected, the exposure index rating can depend on the sensor sensitivity, the sensor noise, and the appearance of the resulting image. The standard specifies the measurement of light sensitivity of the entire digital camera system and not of individual components such as digital sensors, although Kodak has reported[17] using a variation to characterize the sensitivity of two of their sensors in 2001.

 

The Recommended Exposure Index (REI) technique, new in the 2006 version of the standard, allows the manufacturer to specify a camera model’s EI choices arbitrarily . The choices are based solely on the manufacturer’s opinion of what EI values produce well-exposed sRGB images at the various sensor sensitivity settings. This is the only technique available under the standard for output formats that are not in the sRGB color space. This is also the only technique available under the standard when multi-zone metering (also called pattern metering) is used.

 

The Standard Output Specification (SOS) technique , also new in the 2006 version of the standard, effectively specifies that the average level in the sRGB image must be 18% gray plus or minus 1/3 stop when exposed per the EI with no exposure compensation . Because the output level is measured in the sRGB output from the camera, it is only applicable to sRGB images—typically JPEG—and not to output files in raw image format. It is not applicable when multi-zone metering is used.

 

The CIPA DC-004 standard requires that Japanese manufacturers of digital still cameras use either the REI or SOS techniques. Consequently, the three EI techniques carried over from ISO 12232:1998 are not widely used in recent camera models (approximately 2007 and later) . As those earlier techniques did not allow for measurement from images produced with lossy compression, they cannot be used at all on cameras that produce images only in JPEG format.

 

The saturation-based technique is closely related to the SOS technique, with the sRGB output level being measured at 100% white rather than 18% gray. The saturation-based value is effectively 0.704 times the SOS value .[18] Because the output level is measured in the sRGB output from the camera, it is only applicable to sRGB images—typically TIFF—and not to output files in raw image format. It is not applicable when multi-zone metering is used.

 

The two noise-based techniques have rarely been used for consumer digital still cameras. These techniques specify the highest EI that can be used while still providing either an “excellent” picture or a “usable” picture depending on the technique chosen." 

--

Thanks for the summary; I lost the file containing the ISO standard some time ago and was too penny-pinching to obtain a new one.

 

One thing makes me curious: why does the standard differentiate between Japanese manufacturers and the rest of the world?

[Chaemono]

 

One thing makes me curious: why does the standard differentiate between Japanese manufacturers and the rest of the world?

I could post a joke that tries to explain it but it would be construed as non-PC.

[jaapv]

Sure- I get the hypothetical joke . But it still begs the question: Given that the ISO is PC, why?

[M11 for me]

What is PC?

[jaapv]

Politically Correct.

From Wikipedia:

 

 

The term political correctness (adjectivally: politically correct; commonly abbreviated to PC or P.C.) is used to describe language, policies, or measures that are intended to avoid offense or disadvantage to members of particular groups in society. Since the late 1980s, the term has come to refer to avoiding language or behavior that can be seen as excluding, marginalizing, or insulting groups of people considered disadvantaged or discriminated against, especially groups defined by sex or race.

[StS]

I guess this topic is less of an issue for those coming from the film world, where I learned to take box ISO values and data sheets as starting points for my own experiments.

As a rule-of-thumb, I over-expose negative film, if in doubt and under-expose slide film and digital sensors. There are people, who over-expose negative film by full two steps to get the look they want. The best way with an unknown sensor (or film) is to try it out, until the desired results are produced. If I move my Pentax spot-meter slightly to the left or right on the same brightness spot, the LEDs will easily jump 1/3 or 2/3 stops up or down. With the exposure latitude of a modern sensor, this is not a topic in practice.

 

There will never be the correct exposure in photography, unless test charts are taken, so we learn our equipment until it produces the results we want to see. Which is subjective.

 

Unfortunately, the only relevant test can't be shared over the internet - take a picture with familiar equipment, use post-processing as usual and compare large prints at a normal viewing distance.

 

Stefan

[indergaard]

I’m fully aware that there are different ISO standards that manufacturers can choose to use. Fujifilm was the first as far as I know that adopted a new way to determine ISO performance on their cameras.

 

I’m not aware of any manufacturers, except Leica, that suddenly decides to change the ISO standard they use from one camera to the next over night though. I can only imagine the uproar that would happen in the professional industry if the future Canon 5D Mark 5 would under or over expose by about 0.7 EV compared to previous 5D cameras.

 

Why would there be an uproar? Because of inconsistency. Moving from your primary camera to your backup camera would require special treatment, different external metering compensations, etc.

 

I feel this was a completely unneeded change from Leicas part. Leica pride themselves on their history and heritage. And that their glass from 1950 works on all current cameras. Yet they adopt new ways of determining ISO values that doesn’t match their own external light meters, or previous cameras. Makes no sense to me.

[erl]

Well I have/do work professionally with a whole range of Leica cameras (and other brands). I have not had a moments glych with what you refer to as ISO inconsistencies. I simply know my gear and how it responds to my input. I seriously believ every other Pro, and serious amateur does something very similar. If you don't know what is going on, what do you know. It's not rocket science!

 

You just get the money shot, or the gallery shot.

[jaapv]

I’m fully aware that there are different ISO standards that manufacturers can choose to use. Fujifilm was the first as far as I know that adopted a new way to determine ISO performance on their cameras.

 

I’m not aware of any manufacturers, except Leica, that suddenly decides to change the ISO standard they use from one camera to the next over night though. I can only imagine the uproar that would happen in the professional industry if the future Canon 5D Mark 5 would under or over expose by about 0.7 EV compared to previous 5D cameras.

 

Why would there be an uproar? Because of inconsistency. Moving from your primary camera to your backup camera would require special treatment, different external metering compensations, etc.

 

I feel this was a completely unneeded change from Leicas part. Leica pride themselves on their history and heritage. And that their glass from 1950 works on all current cameras. Yet they adopt new ways of determining ISO values that doesn’t match their own external light meters, or previous cameras. Makes no sense to me.

Well, if that is such an essential criterion for you, why don't you select your cameras based on ISO matching? It is not as if this is something new. Even film batches vary, let alone different digital cameras with different sensors, digital hardware and processing algorithms.

Not that I ever noticed any significant problems in the end result. I tend to be aware of which camera I am using.

[Paul J]

Exposure and ISO is very similar. You can tell this because shadow detail is almost identical.

 

Some of what you see may be occurring due to t stop difference, there usually is some difference between lenses, even of the same brand.

 

But it's most likely in camera processing that's different. The Sony looks unnatural but a brighter top end and more shiny image is what they choose to do.

Edited May 5, 2018 by Paul J

[pgk]

 Makes no sense to me.

 

Clearly.

 

You will also find that there are vast variations in the colour temperature exif data from different manufacturers and probably from different Leicas too (I can't be bothered to check).

 

So what  - who actually cares providing the tool you use does the job that you want it to? If it doesn't then try a different tool. Complaining about technical differences in how things are measured or assessed is a first world problem and there's been a thread about this already.

[jaapv]

And even if one judges that the ISO values are different, what is the problem with shooting the cameras in and setting a permanent EV correction?

[indergaard]

Exposure and ISO is very similar. You can tell this because shadow detail is almost identical.

 

Some of what you see may be occurring due to t stop difference, there usually is some difference between lenses, even of the same brand.

 

But it's most likely in camera processing that's different. The Sony looks unnatural but a brighter top end and more shiny image is what they choose to do.

 

 

Not correct. The only reason the images might appear like that is because I disabled lens corrections for both systems.

One of the weaknesses of the Sony Zeiss lenses, like the 28/2, 35/2.8 and 55/1.8, is that they have very strong vignetting, which never goes away, even at f/8 they visible vignette a lot. So that reduces the perceived level of shadow detail in the images.

 

If I import an image from both cameras, that was made with the same settings, lighting, subject, and from the same position, and use the same white-balance and color profile (Adobe Color for example), the images are barely different at all. The colors, shadow, and highlight detail remain more or less identical.

 

The only exception is that the A7rIII is noticeably better at retaining the brightest highlight details, as you can see in the chrome hardware and the wood underneath the strings in this image:

 

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The Sony has a brighter exposure (in regards to the ISO setting used), and retains highlight detail better at the same time.

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Hallo,

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[jaapv]

On my (calibrated Eizo) the righthand image looks better for overall exposure. Another thing that is noticeable is that the Sony has a boosted clarity. Whether the highlights matter ( or would be recoverable on the Leica shot) is a matter of esthetic judgement. To me the grey bands, clearly extrapolated for a non-blown channel, probably blue, do little for the image quality.