Scene luminance has nothing to do with exposure.

but do they take ISO into that valuation ?

So how would you express that in relation to the exif data this forum site displays.

I like this article

artschoolportal.com/2016/11/light-meters-exposure/

Why is this important, you must think that if it is not shown within the exif data then it really did not happen
We know the exposure is different for the flower in between the shots, on film there would be different densities in the negative, to change the density would we not have to alter the exposure for that area. With digital we know that the exposure was altered because more light was captured as shown in the raw, or where the image processing that created the image placed that flower within the tonal range of the image.

www.image-engineering.de/content/library/conference_papers/before_2009/luminance_meters.pdf

scene luminance measurement is basically useless in the field when establishing exposure settings after reading this article, its up to the photographer. which is probably why camera companies and the like dont take scene luminance into account as a measurement to establish a suitable exposure.

www.image-engineering.de/content/library/conference_papers/before_2009/luminance_meters.pdf

Ok the penny has dropped. and i conceive defeat . well sort of

conclusion: exposure = shutter, t stop, and scene luminance which is displayed by the histogram now we have practical picture (pun) to work off.

come on guys you have dropped the ball explaining the concept to the limited scientific minds. 😎

My fees are cheap if you want to quote my conclusion. 😁

Finally.... 😴😴😴

I'm not sure but I think hell has just frozen over 😀

If I understand your concession correctly, does that mean you finally accept that exposure can be defined in layman's terms as the amount of light that struck the sensor per unit area while the shutter was open?

And that only

1. scene luminance
2. aperture
3. shutter speed

affect the exposure as defined above?

Im a practical man. i have to see things . i cant see photons ,luminance ect. but i can see a histogram. my brain is not as advanced and my daughters brain where she can see the concepts as if they were in front of her. its why i could never study biology and science like her, its like defining where does the universe end it pickles my brain. 😁

Yes 😁😀😎

Where did you find those values? I can not see them in Exifs of my pictures. ( Sony and Canon)

me neither, but it did lead me on a search to find out what LV was.

Quote: A histogram is simply a graphic representation of the exposure levels within an image.

It depends on what type of histogram you are looking at - RGB or luminosity

What Is Happening Under The Histogram Hood

So, 7.2 foot-candles, eh?

My references are:
The concept became known as the Light Value System (LVS) in Europe; it was generally known as the Exposure Value System (EVS) when the features became available on cameras in the United States (Desfor 1957).
en.wikipedia.org/wiki/Exposure_value

This is a Composite tag calculated by ExifTool using the formula:
LV = 2 * log2(Aperture) - log2(ShutterSpeed) - log2(ISO/100)
exiftool.org/forum/index.php?topic=7195.0

Your references are?

A pity that the ISO setting is not shown, so no way to check ...

Download Phil Harvey's ExifToolGUI.

There are many, many, many EXIF tags, apps do not show them all.