You won't find dither, ADC inputs, or any number of other things mentioned. They're ignored because they are beyond the scope of the article and its intended purpose and audience.
Sounds like he knew his audience and the broad concepts he was trying to introduce to them and doing so in a way they could initially start to grasp.
so all camera companies are wrong ? whats correct beef burger or ham burger ? fish and chips or fish an french fries [😉😁 accelerator cable or throttle cable . brake line or brake tube [😜
If they say ISO is a component of exposure* then yes, they are wrong. The effect of ISO is applied after the shutter has closed and no more light can reach the sensor. So ISO cannot be a component of exposure*
For example:
For a given scene and lighting -
A. f/8, 1/400s, ISO 200
and
B. f/8, 1/200s, ISO 100
will both output the same image lightness but the ISO 200 shot will have had only half the exposure* of the ISO 100 shot and so will have more visible noise in the shadows because of the lower SNR resulting from the smaller exposure*
Exposure* and image lightness, although related, are two different things and not 2 different names for the one thing.
It's when people use exposure* and image lightness interchangeably as if they meant the same thing that they often get themselves in a twist, especially when I tell them I can change the image lightness in camera while keeping a constant exposure*
What is the definition of the word 'exposure' you use when you use it in sentences?
* exposure - amount of light striking the sensor per unit area while the shutter is open
** optimal exposure - the maximum exposure* within dof and motion blur requirements without clipping important highlights.
*** under exposed - more exposure* could have been added with the DOF and blur constraints still being met without clipping important highlights.
In perhaps a vain mediation attempt :) : Can we agree that shutter-speed and aperture affect the number of photons hitting the sensor, but ISO does not?
Cheers!
Jerry
Artfully conceived and expressed. I'm gonna tuck this one away under the cranial cap.
It depends which part of each camera company you want to look at. The people who write the manuals seem to be wrong, If you delve into technical papers produced by the company's engineers, they seem to know what they're talking about.
The people that write manuals are rarely engineers, they are technical authors.
It's not about 'scope'. It's about writing things that are downright false.
The fact that the negative consequences are less than fatal doesn't mean that there are no negative consequences. What has happened is that a generation of photographers have grown up with a faulty mental model of how photography works, which in general hinders the process of photography.
You admit that you don't see statements like
"A photograph's exposure determines how light or dark an image will appear when it's been captured by your camera. "
"ISO speed: controls the sensitivity of your camera's sensor to a given amount of light"
"higher ISO speeds dramatically increase image noise"
as fundamentally wrong.
Ironically, the topic here is "Exposure is not how dark or how light an image looks!"
We can, if we realize what happens when we set ISO and let the camera choose exposure parameters (shutter speed and aperture) based on metering and ISO setting ;)
The concept he was introducing was not germane in the world we live in. Maybe in an alternate universe where cameras had FWCs of 200000e- and 8 bit ADCs, it would be germane. But it's a red herring.
And completely unnecessary. You can motivate users to move in the direction of ETTR at base ISO simply by explaining how photon noise works. That has the advantage of truth: it is the dominant noise contributor for most photos at base ISO. And it has the additional advantage that, unlike ADC precision, it is a consequence of physics and won't be affected by advances in the CMOS technology that keeps the same broad architecture.
The "half the counts are in the top stop of the image histogram" argument should be consigned to outer darkness, as far as beginners are concerned. It's possible to put some cameras into some modes where, at some ISOs, there is inadequate dither, but that's not the common use case.
By the way, I once had a Hasselblad H2D-39 that carried dither to a ridiculous extreme. It had a CCD sensor with off-sensor 16-bit ADCs. The 5 LSBs were pure noise.
I think we can agree, yes. In physical terms, changing ISO’s will vary the #photons hitting the sensor, FOR a given shutter-speed & aperture (assuming, as you said, that the camera is choosing 1 or both of shutter & aperture).
I’m sure you’d express it in more technical terms (commensurate with your deep domain expertise). But, partly, I’m trying for language that could be easily understood by a “beginner” (as is the concern some here have expressed), while still being fully accurate (as is the concern others have expressed).
Still agreed?
Cheers!
Jerry
Sorry, strike the “assuming phrase”. The #photons hitting the the sensor will vary with ISO at a fixed shutter-aperture combination.
What I'm saying is: suppose, the camera is in Auto (P), and ISO is set to 200. The metering system sets 1/250 f/8. Now let's set ISO to 400. The metering system sets 1/500 f/8. Thus, in this scenario, changing ISO setting changes the exposure and thus the "#photons". Right?
For a given shutter speed and aperture, changing ISO will not change exposure. Given a shutter speed and letting the camera pick the aperture, changing ISO will change the aperture, and therefore the number of photons hitting the sensor. Given an aperture and letting the camera pick the shutter speed, changing ISO will change the shutter speed, and therefore the number of photons hitting the sensor.
But that's a discussion about metering and meter-mediated automation. I think it's confusing to conflate it with a discussion about exposure.
Jim, I was trying to stay away from using the E word, at least for a brief moment, since it seems to cause so much misunderstanding… & boil down to physical essence. Also, as I said in my reply to self above, the “assuming phrase” isn’t correct & I posted too quickly. That said, I realize what you say about the E word is correct.
Cheers!
Jerry
I had to read your post twice… and I’m trying to seek common ground here by distilling to physical essence (& at least for a moment avoiding the E word).
But, yes, the #photons hitting the sensor changes in the scenario you outlined - agreed. I think a beginner can understand that easily & it’s also technically correct. Now… once that understanding is had & everyone agrees THEN perhaps discuss with beginners the historical terms that map on to that physical essence - it might be less confusing for them.
