Camera Meter vs Hand held Meter

Wilt wrote in post #5955238
It is a given that every whole f/stop lets in twice (or half) as much light as the others, which makes the aperture either 1.414x or 0.707x as large.

Bingo.

Wilt wrote in post #5955238
So what is the relationship to these ACR values (which units are those?)

That's what I'm wondering as well. Also: Where does the "100" come from? And why subtract from 100?
("100-46 = 64")

And how does this "64" get to translate to .64 stops?
("+.64 stop light.")

As far as I can see, you'll always get around 1.4 (give or take a few hundredths) as outcome to your calculation. That's because it's a one stop difference.

Where you go wrong is in "translating" that into a +.65 (or so) correction in ACR.

René Damkot wrote in post #5955886
Bingo.

That's what I'm wondering as well. Also: Where does the "100" come from? And why subtract from 100?
("100-46 = 64")

And how does this "64" get to translate to .64 stops?
("+.64 stop light.")

As far as I can see, you'll always get around 1.4 (give or take a few hundredths) as outcome to your calculation. That's because it's a one stop difference.

Where you go wrong is in "translating" that into a +.65 (or so) correction in ACR.

If you take the 16 pic posted and you up the exposure you get to around +.64 where everything looks fairly balanced and not clipped.

I took the long way but it is pretty clear the .64 is a percentage ( 64% ) .

The difference between the top f stops (f11 and f16) when divided by a focal length (naturally you use the same focal length).

What I'm saying is that the difference between f11 and f16 is 1 stop according to what people say.

I ran took 85mm/11 and 8/16 then took the the processed numbers and divided the small into the big one.

You say it's always going to be 1.4 since it is one stop.

Should 1 stop not be be better represented by 1?

My point is that according to you, you'd have to add 1.4 as the difference (which is equal to 1 stop).

I'm saying that the difference is more like .64 (and ACR confirms it).

No more replies to this thread.

I'm perfectly happy with the fact that I can verify my results in ACR and on paper.

If you need closure you can just think that I'm dividing oranges by apples to get watermelons.

Alexajlex wrote in post #5960055
If you need closure you can just think that I'm dividing oranges by apples to get watermelons.

Works for me

Alexajlex, I wish you well in your photographic learning process, and that accept information when it is offered in the future, so that you get a proper understanding rather than believing an intuited conclusion.

BTW the 1.4 is a multiplier of the diameter of the aperture size expressed in millimeters. An aperture which is 1.4x the diameter of the starting aperture admits 2x as much light...it has to do with the area of a circle.

diam 1 1.414 2 2.828
radius 0.5 0.707 1 1.4​14
area 0.78 1.57 3.14 6.​28

...bigger area of the circle is what determines the amount of light getting thru to the sensor or film. Notice that to double the area, you increase the diameter by 1.414x