Thanks again, Tim. I know I´m trying to exchange something that is not correct with somthing that isn´t perfect either. But I´m afraid your approach would confuse most people. In my experience there is little knowledge of even the basic things most learned at school, 5 years after they left school. So of course I could create a scientifically correct chart with all the info starting with photons and going all the way to A/D conversion. But that´s exactly what is intimidating so many people when it comes to photography. I want to show them how easy it is to create great images. Yet many people have issues understanding what causes image brightness. I want to pave their way to easier get there rather than being scientifically correct.
I know I was asking for harsh ctitique - and I absolutely appreciate all of the comments and the thoughts and time that went into your answers. It helped me improve certain points, but I´m afraid incorporating your approach would make the chart not usable for most people new to photography.
I hope for your understanding.
There is a PS. to this and it requires that you ask yourself what it is that you are trying to achieve.
Are you trying to illustrate an abstract concept in a way that your student finds easier to understand or are you trying to nail an abstract concept into absolute values so you can form an understanding?
If it's the former then you must be vague because it is only then that the student will question and learn. If you force your own absolute version then you deny them the ability to work it out for themselves, you suppress thought and learning, you simply provide your rigid idea.
The use of a rigid language with strict definition is a device that's been used for centuries by Authoritarian Bodies to suppress free thought and control bodies of people. Take *subversive* or *suppressive person* as examples, once the label is applied then the exact nature of the person and your behaviour towards them is defined and demanded. There is no room for your personal judgement.
When teaching you must remember this and allow the student room to make their own connections and understanding. You have to trust and encourage them to question and think, not do it for them. I find your original confused and fairly incomprehensible. As I said it bulldozes through abstract connections and concepts in a way I found difficult to *un-learn*.
Image brightness is a fairly abstract concept as the output space, (monitor) has a fixed range of brightness. You can control it better with the brightness knob that you can with the camera shutter speed, and neither will allow you to reproduce consistent and neutral skin tones in print. Less exposure (absolute light on sensor) = darker image/more light = brighter image is simply an incorrect and misleading concept. What it translates to in reality the inability to achieve consistent colour in images.
So lets consider another output space for images which similarly has a fixed back and a fixed white, the brightness of which you can't vary, (just like a print or computer monitor). Take a white piece of paper and a graphite pencil. Now explain to your student, who's advanced a little and is eager to learn more, how to create bright and dark images.
Take the two images below, one looks like it is taken in bright sunlight and the other in darker diffuse light. Yet both have exactly the same range of brightness on your screen, in fact the lower one has the greatest proportion of lighter tones, it's actually brighter:
View attachment 169325
View attachment 169326
You're trying fit everything into your understanding, you trying to squeeze it so it fits into your incomplete logic. And in doing this you deny your student the tools to progress beyond you, they will always be limited by what you don't understand. It's another abstract concept but one you must accept. The aim of teaching is in getting others to progress beyond you, not limit them.
By far the biggest problem and limitation I find on forum and Internet based learning is people trying to force photography into the logic of *left brain* thought. I can't stress what a handicap this is for those who wish to pursue a more creative *right brain* approach. You basically imprison them within the confines of your own self imposed pigeon holes, the logical structure you impose so you can understand. But by teaching that rigid logic you deny them the opportunity to understand and make the abstract connections that are essential to creativity. To take an obvious one, how many photographers understand that texture is the memory of touch and not the visual reality contained in reflected light? Does your teaching allow the student the possibility of making that connection themselves?
Exposure is about being able to produce consistent and repeatable tones on light sensitive media. What you do with them afterwards is another essay, but start with the ability to do this.
I'm sorry for the essay, and it's not all on your shoulders.