The Exposure Triangle Is Misleading And Unnecessary.

Hello Dave,

And if I use my Sigma in Manual everything and only look at the raw histogram, the ISO setting does nothing at all, surprise! ...

Is it a fact? When I got my first digital camera at the end of the previous century, I asked a Kodak eng. what ISO dial does. The answer was - don't use it, it does nothing good :)

No, it’s the photons.

so why even put it on the camera ?

To make people feel warm and fuzzy, in a familiar place. Turned out to be a mistake, and very soon.

Gain is about noise.

As an example you imply a RAW-only workflow, so it can’t be true in the general sense. I gave a slightly edited example in the referred post how I think your statement would be true.

And JPEG lightness.

whats the histogram used for ? and what inputs are needed for it to work?

so i can see my subject in live view on my studio monitors, doesn't need to be for a recorded image only.

Sampling is about noise.

funny that i shoot raw in the studio and apparently dont need to set iso🤨

this is even getting better ,im on a roll. apparently if you shooting in a dark studio to increase exposure to the photodiodes you slow down the scan rate of the sensor. where does shutter speed come in to that equation on exposure 😁

In modern CMOS sensors, there is plenty of read noise to dither the ADCs properly at all ISO settings when the camera is set to 14 bit precision or higher.

25 years ago Phil Askey told us in his reviews that the ISO knob turned up the analogue amplification. That suggested that you could reduce exposure and compensate for this with more amplification. This sounds like the sensor is thus a device that can have variable sensitivity depending on the level of amplification and, therefore, the ISO knob effectively acted like a film with tunable sensitivity. Perhaps this was just a metaphor to ease the early transition from film to digital. For many years I took this at face value and believed it. I'm over that now. I recognise that this is not true with current sensors (and probably wasn't true 25 years ago either) and is a mis-leading model to have if you want to understand what really happens. I am most definitely not fixated on this and this is not a block.

I do want to understand what really happens to about the level I understand how aperture works, how shutters work and how to make use of that knowledge to produce art. However, I currently don't have a replacement working model for the old ISO=film speed one.

You might reasonably expect that a beginners thread on the subject would quickly and easily explain it. I've read many of the posts in this thread and others in the beginners forum, some of Jim Kasson's posts and the two part special on ISO over on DPReview. And particularly the hideous thread here on ISO. None of this stuff has helped my understanding one iota, no matter the good intentions of the authors. From my perspective almost every explanation ends up being baffling inconsistent, confusing, contradictory, muddied in endless detail and dispute between participants and therefore effectively incomprehensible.

Now I don't claim to be particularly smart, but I'm educated to undergraduate level and not totally stupid, so I ought to be able to understand a reasonable description of how something works. There must be a reason why I'm not getting this despite all the reading. I accept I'm partly to blame, but I also suspect that there is something wrong with the communication. It's not the right style for beginners tutorials. There is too much insistence on accurate details. A bit of looseness is ok for beginners as long as it is clearly understood the explanation is at novice level, real stuff later. The trick is to find a level and style of explanation that omits or fuzzes much of the detailed technical explanation but still manages to get across the fundamentals. What we don't need is a bunch of experts refusing to allow any approximation to go unpunished because at a beginner level, this kind of pernickityness just confuses. And frankly puts one off wanting any level of understanding.

Perhaps I can direct a little by asking a narrower question. What does increasing the analogue amplification actually mean? What does it do to the raw data. What would happen if there was zero amplification. What would happen if there was a million times amplification? What are the benefits and the downsides to this amplification?

EDIT: It seems to me that if could successfully parrot back a reasonable description of such things, it would be a hint I was beginning to understand it. Because I certainly can't do that at the moment. But all understanding is a kind of circular iterative process, and confidence to move to the next step comes from a some kind of foundation, however crude that understanding. Maybe for experts, that's hard to remember.

Wow…it’s so odd seeing threads over 150!

In-camera histogram in current consumer cameras isn't useful to me. It misrepresents raw data, grossly.

Judging by how it went so far the 1,000 mark will be reached soon, and beginners will start to throw their cameras away ;-)