According to Tony Northrop, ISO in digital cameras are fake?

I'm an old dog that loves film for over 50 years but is the ISO standard in digital cameras is fake? As a film shooter also, ISO is very real and I do film test to establish my personal ISO. Tell me your thoughts about this video.

Fake as in there is no ISO standard for digital imaging or fake as in it is not the same ISO standard as for film speeds?

Watching some of the video, I got the impression the presenter did not really have much of a grasp of what he was talking about.

Based on his results, I think he is correct about the fallacy of using ISO in digital cameras. Using Gain instead of ISO would be a more honest term. Cameras with higher gain (higher maximum ISO level) may have sensors with higher signal-to-noise ratios. If they raised max ISO to say 1 million, as he suggests, the noise would probably be too much with today's sensors, or if the light was high enough during exposure, the amplified image would be of course way to bright. So the ISO range is probably related to S-to-N, and there is probably some difference in sensor quality reflected in their max ISO rating.

I rarely use digital cameras, and don't own one, and always thought the camera turned down the gain as the image was being made. Knowing that "ISO" is a post-processing phenomenon is very helpful.

ISO isn't fake but an image sensor has only 1 ISO rating.

It would be interesting if they could design a shutter system which could take multiple photos in very rapid succession and then focus stack them for you to reach the appropriate "iso"/exposure like the astrophotographers do. That way you could increase the signal portion in that signal to noise equation.

mmerig said:

Based on his results, I think he is correct about the fallacy of using ISO in digital cameras. Using Gain instead of ISO would be a more honest term. Cameras with higher gain (higher maximum ISO level) may have sensors with higher signal-to-noise ratios.

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Not sure what is fake. There are ISO standards for digital cameras after all. Wouldn't it be more honest for film cameras to refer to sensitivity rather than ISO?

ISO stands for International Organization of Standards. Seeing as how ISO dictates how those numbers are calculated (it's actually a measurement of sensitivity), it's kind of hard to argue that digital camera's ISO ratings would be fake, unless some other organization came up with their own standards and called them the ISO standard as well. I guess you could argue that ISO itself is fake, since they took their sensitivity rating directly from ASA (American Standards Association). But in any case, ISO sets the standards now, and it is whatever they say it is.

There are some interesting angles to digital sensors when it comes to the ISO standard. For instance, a sensor has but one native sensitivity. It can then be altered with either analog, digital, or software amplifiers or attenuators. Then again, the sensitivity of film can be altered with different chemicals and processes too.

I don't think the point of the ISO was to be the final word in how everything is to be done, but rather to give a baseline to allow the end user to form some reasonable expectations prior to usage. In other words, it's just a number to give you some idea of what to expect to allow you to compare products.

Who cares? Unless you are using a hand meter and then running the camera in manual mode it really doesn't matter.

Chan Tran said:

ISO isn't fake but an image sensor has only 1 ISO rating.

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Are the ISO ratings enhanced by amplification of the digital signal from the sensor?

"we don't use film anymore." This is why I don't like Northrup. Never have.

Anybody wasting time watching Tony Northrup's videos deserves what they get. It is all clickbait and hyperventilating. This is just the latest example.

mmerig said:

Based on his results, I think he is correct about the fallacy of using ISO in digital cameras. Using Gain instead of ISO would be a more honest term.

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Though I prefer to shoot film, I still think digital technology is pretty amazing. In film terms, to me, increasing the gain with analog is push processing film. But pushing film rarely increases shadow detail like digital sensors.

I watched the video and he didn't state the ISO standard. I never saw the ISO standard (because I don't want to spend the money to purchase a copy) but I do believe the reason camera manufacturers could do that because the ISO standard gives them a lot of slack. I believe despite of the variation he found all of the cameras conformed to the ISO standard.

Ces1um said:

It would be interesting if they could design a shutter system which could take multiple photos in very rapid succession and then focus stack them for you to reach the appropriate "iso"/exposure like the astrophotographers do. That way you could increase the signal portion in that signal to noise equation.

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That is called HDR and most cameras do that. Not sure what you define as rapid. It is not a focus stack, but an exposure merge. Lot of cameras have built in focus stacking also.

Part of the issue is that digital sensors do not have a shoulder. So if you overstate ISO a bit, maybe you decrease chances of clipping highlights?

Also, read a couple of articles on this and the concept of ISO-less sensors. The key issues are noise, and this is sorted into two types of noise (at least): pre-read and post-read. Pre-read noise gets amplified, post-read does not. So it is a bit more complicated than he is stating. If you shoot RAW, ISO is less of an issue, but because of pre-read noise, it is not non-existent. Here are a couple of articles. At least one is part of what I read (the 2nd one):

https://fujilove.com/isoless-photography-with-the-fujifilm-x-series/

https://photographylife.com/iso-invariance-explained

So we are dealing here with "ISO equivalents", no?

Definitely a First World problem, this. Another term, Teacup Tempest, comes to mind.

Or clickbait?

So who the heck is Tony Northrop anyway?Who does he think he is? Who does he want to be?

Now let's just all go out with our camera and shoot some nice images, full knowing we are entirely free to set whatever "ISO equivalents" we like.

EYD!

Who?

jim10219 said:

There are some interesting angles to digital sensors when it comes to the ISO standard. For instance, a sensor has but one native sensitivity. It can then be altered with either analog, digital, or software amplifiers or attenuators. Then again, the sensitivity of film can be altered with different chemicals and processes too.

I don't think the point of the ISO was to be the final word in how everything is to be done, but rather to give a baseline to allow the end user to form some reasonable expectations prior to usage. In other words, it's just a number to give you some idea of what to expect to allow you to compare products.

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One of Northrop's main points is that even what could be called the "native ISO" of a sensor is not consistent across camera models. The ISO standard for measuring sensor speed is constrained, or in other words, there are definite protocols. The camera manufacturers are apparently not following them (it was difficult for some of the older models, but no excuse now), so their reported ISO speeds could be called fake, or at least, loose.

Sure, it's a first-world problem, (as ozmoose mentions ) but nearly everything in photography is, so why so much animosity towards this particular topic, or Northrop?

I never heard of Northrop before. I think he made some succinct points with information to illustrate them further. Statements like "we don't use film anymore" do not bother me -- I did not even notice it -- and I do not own, and rarely use, a digital camera. But I like learning about them.

I've read some bloody absurd threads on this board over the years and this one is up there with them. This is an argument about nothing more than a convention to express the relative sensitivity of either sensitised material or an imaging chip. ISO is a number system, nothing else (and it used to be called ASA while DIN was a log system that worked equally as well). What else should the inventors of digital cameras have called the measure of their cameras' sensitivity that would render it easily understandable and relevant to existing cameras and photographers?

I have heard of Northrop - An American company - they used to make quite good aircraft.....perhaps that is not the same thing.

The relativity between ISO and a sensor. is as the designer intended and behaves as such. Take a picture of something with a low digital ISO and the exposure is longer or you have to use a wider aperture for the same exposure. Take the same scene with a much higher digital ISO and the picture is recorded with either a smaller aperture or a shorter shutter speed. This is exactly the same as film would behave using similar settings in ISO/DIN/ASA/Weston/ Hurter and Driffield or any other of the assorted settings used for film, past and present

Also like film, if you use a low ISO (or whatever you want to call it) the quality produced should be is at its highest. Use a high ISO and you start to get noise appearing at smaller enlargements. For noise substitute the word 'grain', as in the film world.

It is a rather silly argument which I would suggest, any practical difference is only the figment of Mr Northrop's over active imagination. He really needs to get out more!!!!

markjwyatt said:

That is called HDR and most cameras do that. Not sure what you define as rapid. It is not a focus stack, but an exposure merge. Lot of cameras have built in focus stacking also.

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Not quite what I was getting at but close. Astrophotographers will take hundreds, if not thousands of the same photograph. Then they'll align each one and layer them over one another until a photo finally emerges. They deal with very weak signals (light emitted by stars billions of km away) and by stacking thousands they increase the signal portion of the signal to noise ratio. If your camera took let's say 10 photos when you depressed that shutter once and then stacked them one on top of each other, this could help overcome poor lighting conditions, allow you to use your cameras lowest iso, allow for the use of a high shutter speed. This is different than taking a photo exposing for the shadows and a second exposing for highlights and then merging them to provide a high dynamic range, but it is similar.

paper isos are fake too, not sure why any of this matters

Digital imagers are a different media than analog silver halide, so a different ISO standard applies. As a matter of fact, the number of ISO standards that apply to digital imaging is absolutely massive, covering the full breadth and scope from design to use to storage of the digital media.

It's a fallacy to say that a digital sensor has a single sensitivity: There is no functional equivalent to traditional analog sensitivity in the digital world. Rather, the output of a digital camera is a function of the Spectral Quantum Efficiency, Fill Factor, Well Capacity and the exposure time (more correctly the integration time), dark current, Bayerian filter recombination schema for color sensors, analog gain setting, Bit depth of the A to D converter, and finally the digital gain setting. Of these, the only real analogous equivalent to film photography is exposure time. The other parameters are dependent either on the physical properties of the silicon detector or on the design of the FPA and ROIC itself (not to mention the post-processing which occurs downstream of the digital gain stage on the output of the A2D). That said, when you really want to geek out about the physics of the processes, Quantum Efficiency was often compared in the early days....but QE has to be redefined for analog as the efficiency of the conversion of photons to developing centers on the grain. Put another way, that process wasn't widely known as "QE" before digital imaging came about. See http://www.imaging.org/site/PDFS/Papers/1998/PICS-0-43/622.pdf for one of the earliest examples.


Analog and digital imaging are almost entirely two different animals, the functioning of which are about as closely related as film photography and oil painting. All three of these media mentioned produce an image in entirely unrelated ways, but the end result -- an image observable with your eyes -- are equivalent (if the oil painter is a realist).

Rather than fall into the trap of analogies between the two media, you really have to consider the digital Focal Plane Array as an entirely different type of imaging system. Blame the early producers of digital cameras for the common practice of trying to compare the two media directly. Looking back to the days before digital photography hit the scene (i.e. the 1980s and 1990s), users of digital imaging systems evaluated the performance of those sensors in terms that made sense to the capture of an image through the photovoltaic effect rather than silver halide. However, discussing the capabilities of the digital camera in terms which make sense to those users -- who lie outside of the realm of consumer / commercial photography -- would have left film photographers unable to appreciate the benefits of the digital cameras that manufacturers were hoping to sell in the early 2000s.

So either independently or in conjunction, all those parameters that affect the digital output aside from exposure time were rolled up into a single sensitivity value equivalent to film's ISO rating, the high equivalent numbers of which were then (conveniently ignoring the very important SNR values) touted as a significant benefit to using digital imaging. Having been a digital imaging user and designer outside of the realm of consumer photography at the time, I watched this comparison of ISO rating spring up and establish itself in the consumer photographic market. Its use is unique to this particular digital imaging market. Satellite imaging systems, for example, have no ISO rating listed in their detailed engineering / user performance specification nor even in management power point presentation because it is misleading in understanding the true sensitivity and performance of the imager.

So from that perspective, what the guy is saying is sensible. However, that sort of rationalization is only one factor in defining the terms that a specialized community adopts. Simplicity in understanding, rules of thumb, and tradition have as much or more to do with terminology as anything else. Very few photographers will recognize the meaning of the term Double Gauss, but we all know what a 50mm lens is (they are both the same thing, almost without exception).

Ces1um said:

Not quite what I was getting at but close. Astrophotographers will take hundreds, if not thousands of the same photograph. Then they'll align each one and layer them over one another until a photo finally emerges. They deal with very weak signals (light emitted by stars billions of km away) and by stacking thousands they increase the signal portion of the signal to noise ratio. If your camera took let's say 10 photos when you depressed that shutter once and then stacked them one on top of each other, this could help overcome poor lighting conditions, allow you to use your cameras lowest iso, allow for the use of a high shutter speed. This is different than taking a photo exposing for the shadows and a second exposing for highlights and then merging them to provide a high dynamic range, but it is similar.

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The term is stacking frames. As you describe, it's important for astrophotography because there is a limit to how dimly an object can be photographed before ambient background lighting "skyglow" becomes unacceptably large. This sets the maximum exposure time, however the extended objects in the sky are so dim and such of low contrast that you have to stretch the heck out of the histogram post-processing to produce a reasonable contrast between object and background in the final image. This action not only makes the object easier to see, but also makes the noise in the frame easier to see. So stacking and averaging multiple frames takes advantage of the fact that you can reduce the temporal noise relative to the object being photographed by a factor of sqrt(n), where n is the number of frames you average, to smooth out the background. This doesn't address fixed pattern noise (the noise floor that doesn't vary from frame-to-frame), but that can be removed with a dark frame subtraction...that is, recording the fixed pattern noise floor and then subtracting it from the final image.

Ces1um said:

Not quite what I was getting at but close. Astrophotographers will take hundreds, if not thousands of the same photograph. Then they'll align each one and layer them over one another until a photo finally emerges. They deal with very weak signals (light emitted by stars billions of km away) and by stacking thousands they increase the signal portion of the signal to noise ratio. If your camera took let's say 10 photos when you depressed that shutter once and then stacked them one on top of each other, this could help overcome poor lighting conditions, allow you to use your cameras lowest iso, allow for the use of a high shutter speed. This is different than taking a photo exposing for the shadows and a second exposing for highlights and then merging them to provide a high dynamic range, but it is similar.

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With most HDR set-ups you choose the number of exposures. Unlike astronomers it is not 1000s, but typically I hear 5-10 exposures, so (as you say) it is similar.