Thank you, Michael. I've downloaded them and will dive in as soon as I can.
I think you might be a bit surprised. I really have no issue with not knowing certain things.
In the field I'm much more interested in concepts I can visualize rather than math I have to do.
Thanks. If you look in my gallery, you will see photos taken at 600 or more MPH, upside down! I was not worried about curves then. It is clear that using a film is different than designing one. This discussion is too over the top technical by those that do not have the background for the technical aspect.
I have seen both sides and used them both to get good results IMHO.
Another way to think of this is that "box" might be considered somewhere close to where the first high quality print can be made and the limit of the "extra" category would be where the last high quality print can be made.
There are real reasons to consider these alternate placements.
Exposing for the last HQ print point might eliminate the need for carrying an ND filter.
Exposing extra somewhere between the limits could also give you consistently longer print times, making complicated burn and dodge work more manageable.
An example of the use of truly over is a high-key technique I used in studio, the subject is lit to provide proper placement for easy printing at the desired level. The background is then lit to truly overexpose well beyond where detail could be recovered. Creates a stunning white that leaves the subject beautifully isolated.
The example below would be how it would look using a single set of curves. This is the maximum Luminance range my program can do and I think pushing everything into the toe of the paper curve has freaked out the tone reproduction reference line.
But what you have is one scene with a normal luminance range normally exposed and printed and another scene overexposed and printed for high key like in the next example.
As compared to a typical high key approach. The scene has a slightly shorter than normal luminance range. The main difference here is that it falls under 100% reflectance (the subject is shifted to the left in Quad 1). The exposure is placed higher on the curve. Development is reduced some, and the subject is printed in in the toe of the paper curve.
Stephen the single example below expresses my whole high-key placement idea, 2 lines and 2 squiggles in the sand with my finger.
Everything I need, to explain my idea to a companion on the beach with me is there.
It can even explain why I might want to use a highlight or mid-tone to peg exposure instead of a shadow.
I think what is being expressed s that there is a pretty low threshold of knowledge of the system needed to do truly nice work, beyond that point things might fall into the nice to know range or in the who cares range depending on the photographer.
Henri Cartier-Bresson is a reasonable example of this, he said in his own words (paraphrased here) that he did not care to know what happened after the film came out of the camera. He said of himself "I'm a hunter, not a cook".
Stephen, I like the long luminance range (single set) example actually. I think this type of illustration is powerful.
I disagree with PE - I don't find these tone reproduction discussions over the top technical. In fact they are quite straight forward.
One thing I'd throw into the mix as far as over/extra and latitude goes is a consideration of image structure characteristics such as granularity, resolution etc. which may or may not contribute to the total subjective sense of print quality in addition to "macro" tone reproduction. As we know these characteristics are influenced to some extent by exposure.
If you look at my example, you will notice nothing falls off a curve. High key is just supposed to lighten the tones not to blow them out, which is what it appears to do in your example.