But what if you are not interested in backwards compatibility with film? Would you deny us at least one camera with good RAW exposure aids and therefore no ISO setting!
If you remove the sensitized material, then you don't have exposure anymore, just a radiation and so on no photograph.
Well,
strictly you still have 'exposure', in that exposure is defined as the luminous energy density at the focal plane, so it is till there and can be measured.
What you don't have is 'an exposure'.
Great. You have exposure, but you do not have an exposure. Pure semantics.
Are you serious? The use of the 'semantics' card as an excuse for sowing confusion and sloppy thinking.is an old trick on the part of those that simply can't or don't want to understand things. 'Exposure' has a defined meaning in photography, as a quantity.
Here it is in a Kodak T-max data sheet
I'm hoping you're not going to claim that Kodak doesn't know what 'exposure' is. Look at the x axis. It's labeled 'log exposure (lux seconds). The Y axis give the density. So there it is. Exposure, in lux seconds. You can measure that, and the measurement doesn't change whether or not there is a film there. 'Exposure' is independent of the film, whether you think that is 'semantics' or not.
Look at the tittle of the graph. This is a graph for a film. If there was no film, the graph would contain no curves. It would be just empty. A perfectly horizontal line at density 0. You need to have a light sensitive media to record something.
Just irradiating a piece of paper does not record or capture or measure or plot anything. It just displays something.
Here's a nice graph
What you're proposing is if you forget to put solar cells out, the months January-December don't exist. Interesting idea.
There can be the quantity that is called 'exposure'. You can't have 'an exposure'. The problem here is the common one when the same word is used to mean two different but related things. That is why I try to use different words, beacuse you have to think clearly to differentiate things if the same words are used.
Semantics.
Anything you're in capable of understanding you dismiss as 'semantics'. Actually, it is you playing the semantic game, insisting on your own definition of words that already well and rigorously defined.
Just accept that in Photography, exposure means "an exposure"
Why would I, when it isn't true that is the sole usage of the word 'exposure'? If it were, it would be hard to talk about 'overexposure', wouldn't it?
Whether that be sensitized material or a sensor. If you just want to look at a picture on a sheet of white paper without recording it, that is maybe photoscopy but not photography
Exposure, quantity, as defined in sensitometry (which I guess is the word you're looking for) versa 'an exposure', which nowadays we tend to call 'a capture'.
No it's not at all the word I was looking for. Sensitometry (from sensitivity an metering) is the study and measurement of light sensitive materials. A blank piece of paper is not light sensitive.
The science of sensitometry involved the study of the phenomena which stimulated the light sensitive material (that is, electromagnetic radiation). its quantification, in photography with respect to the luminosity function (which as an aside is why there is 'luminous exposure' and 'radiometric exposure - look them up - and people don't talk about 'a radiometric exposure' to mean the x-ray image made at the hospital.
That is already covered by the definition of the "exposure".
Which definition of 'exposure' are you working to?
The one used by millions of photographers in photography during the past 100 years, not the one used in physics.
In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance.
Now you're really confused. That is the one in physics. It defines the light
reaching the film, not the consequence of that light reaching the film. So. The problem now is clearly you can read the definition of exposure, but apparently you can't understand it. Do you know what a lux second is? Or a lux? or a lumen?
Who is the confused here?
You.
The definition of exposure in physics does not mention film, or any light sensitive media for that matter.
What substantive difference does it make to the exposure, measured in lux seconds, whether or not there is a film or sensor there? Other authoritative sources would use the formulation 'at the focal plane' as opposed to 'reaching the film or sensor'. Wikipedia worded like that because the author of that paragraph though that made it easier for lay people to conceptualise. The 'exposure' is the same, there is no 'physics' and 'photographic' exposure, you made that up.
The definition of exposure in photography does.
So, what is different between what you think is 'physics exposure' and 'photography exposure'? 'Physics exposure' is measured in lux seconds. What is 'photography exposure' measured in, if it's different? In any case, the one that ISO uses in its standards, the one that Kodak uses in its data sheets, and the one that's relevant is what you're calling the 'physics exposure'. I'd refer you to this text, from ISO 12232:2006
Which makes it clear that IS believes that the 'exposure' is what occurs at the focal plane, and can be measured independently of a sensor or film being in place.
Seriously, you are being ridiculous. You keep on crying 'semantics', but what you're engaging in is a textbook example of semantic quibbling to cover for your own lack of understanding. You've invented a whole semantics of 'exposure' all your own, made a novel differentiation between the 'exposure' which apparently physics uses and the 'exposure' that photography uses. What are the units of 'photographic exposure', by the way, because, as I say the ISO standards for speed and exposure index all use the 'physics one', which comes in lux seconds. They don't mention any other version of exposure at all. Why is that?
If you want to eliminate the sensitivity,
Which definition of 'sensitivity' are you working to?
The one used by millions of photographers in photography during the past 100 years.
Your evidence that 'millions of photographers' have used this confused definition?
In photography sensitivity refers to a film or digital camera sensor’s sensitivity to light. In photography sensitivity is often referred to as ISO.
Not a great definition (you didn't cite the source but I found it
https://shuttermuse.com/glossary/sensitivity/ - random web site, not always the best way to get good material if you don't know what you're doing) because it's circular 'sensitivity is sensitivity'. What definition of the second sensitivity are you working to?
I know very well that film speed or exposure index is very commonly misnamed 'sensitivity', even by camera manufacturers. However, the real issue is in the semantics. What do you actually mean by 'sensitivity'? When ISO defines, in the ISO standard 'Standard Output Sensitivity', they say exactly what they mean by it. And what they don't mean is any 'sensitivity' of the sensor.
Yes they do, indirectly. Because ISO defines the properties of the developed image.
That's a non-sequitur, and even if it did follow, it's a false premise. The 'ISO' for negative films doesn't define anything of consequence about the final developed image. The 'ISO' for reversal films only defines the density at one point, with respect to exposure and development process, and the standard for digital defines the lightness at two points (as alternatives). They define absolutely nothing else about the 'properties of the developed image'.
But there can be no developed image, without there being first a light sensitive medium. In the case of film, the properties of the film together with its processing define the properties of the developed image.
Sure, but digital doesn't use film. A sensor isn't film, and the digital ISO standard understands that.
Speed of a negative film is validly a 'sensitivity', since what is measured is a minimal response to light (the speed point), and thus it fits the normal definition of sensitivity, which is 'is the minimum
magnitude of input
signal required to produce a specified output signal' according to Wikipedia.
Something we can both agree on then
Yes, and when you think about it, it explains rather well how the misapprehension that 'ISO' is 'sensitivity' originated.
The 'speed' of reversal film and digital is somewhat different,
No, not really.
Yes, really.
Reversal films have a much steeper gamma. If you look at the film graph you posted above, the curves are much more vertical or steeper. A small change in exposure causes a larger change in density, than is the case in negative film. That is why reversal (positive or slides) film needs to be exposed much more accurately. But they still have a valid sensitivity as negative film does.
Your views about what these emulsions are like are irrelevant. All that matters is how ISO (and ASA and DIN before them) decided to design their speed ratings. Luckily for us, the panels of experts involved understood the whole thing load better than you do. Here is the issue. The aim of a speed rating for negative is to ensure that the negative captures as much information as it can about the scene. The actual density of the negative isn't of much interest, because the printing process, and a second exposure at that stage, will deal with that. So, ASA/DIN/ISO (ISO 6 for B&W, ISO 5800 for colour) defines 'speed' for negatives based on a 'speed point', which is a level of bare reactivity to the light, the assumption being, get the shadows right and the rest will follow. For reversal films there is a different standard (2240) because exposure needs to be set differently for these, such that the final, developed image (which generally has a chemical exposure, heaven forfend) can be viewed and present a convincing rendition of the film. Thus reversal speed is rated around a different density level, around the mid range. The standard for digital (12232) is different again because digital doesn't have a 'density', so instead exposure is referenced to a point in the 'value' scale (as in 'value' in the HSV colour space). The equivalent term 'Lightness' (as in the Lab space) is more descriptive and to be preferred when trying to explain to lay people. This is a point in the processed, output image. All that matters to the ISO standard is what is the exposure (in your terms, 'physics exposure' at the input and the image file (in sRGB colour space) at the output. ISO defines nothing at all about what goes on in between.
as the wikipedia article on film speed says: 'A closely related ISO system is used to describe the relationship between exposure and output image
lightness in digital cameras.'
ISO is a standard
ISO is a standards organisation.
, and as such it changes over time to adapt to technology. It was changed to adapt to the particular properties of digital sensors.
There are different ISO speed standards to suit the different requirements and role of different media.
then you need to eliminate exposure as well as they are locked together and so on "photography" doesn't anymore exist and you need to invent everything, only to come back to what we have today.
A complete fallacy, probably purposeful.
It has served photographers well for over 100 years.
I don't think photographers for over 100 years have been saying 'you need to eliminate exposure'. Do you have any evidence to support that statement?
It's you that wants to replace the traditional definition of exposure in photography, not me.
Absolutely not. I stick the definition that you gave as the one that you think is right (lifted from Wikipedia, I think), that is embodied in all the ISO standards, in those film data sheets by Kodak, Fujifilm, Ilford and so on. The one you'll find in reputable texts such as the Manual of Photography. It's you that wants to split 'physics exposure' and 'photograph exposure'.
If you want to succeed, you have to show cause. Show us a real practical advantage. It will not change just because of scholarly obsessions with "scientific correctness". There has to be a real advantage.
Back to you. I'm not redefining, you are. Show cause.
I sometimes fall in the same traps as you - like when ordering 10 cubic meters of pine bark at the garden centre. I get a puzzled look. Then after 5 seconds....ahhh, you want 10 meters mulch.
That's not the trap you're falling into. The trap you're falling into is choosing to argue at length about a subject that you don't know very much about, and rather than taking a break to educate yourself, making it up as you go along. Doing that generally ends up with you making a fool of yourself. And you're not doing it just with me, you're doing it with Iliah, who knows this stuff inside out, backwards, forwards and sideways. If he says you're wrong about that, you're wrong about it. Been there. Done that. Got the T-shirt.
--
Ride easy, William.
Bob
