Sandman
Your reading comprehension problems is of no concern to me.

nospam
i don't have a reading comprehension problem nor do i have a math comprehension problem.

Sandman
http://www.merriam-webster.com/dictionary/arithmetic%20scale "a scale on which the value of a point corresponds to the number of graduations the point is from the scale's zero"

I.e, a doubling of the value (ISO 100 ->200 ->400) is related to a doubling of the scale (for instance).

I.e. ISO is arithmetic.

nospam
nope.

read the definition. the value of the point does *not* correspond to the graduations, which means it's *not* arithmetic.

a change of 25 means something very different at 25->50 (1 stop), 100->125 (1/3rd stop) and 1600->1625 (insignificant).

Sandman
Just because you don't understand it doesn't make it untrue, you know.

nospam
that applies to *you*.

once again, you're insisting you're correct in the face of evidence to the contrary and what's hilarious is that this time, *you* provided the evidence!

Sandman
http://www.merriam-webster.com/dictionary/logarithmic+scale "a scale on which the actual distance of a point from the scale's zero is proportional to the logarithm of the corresponding scale number rather than to the number itself"

I.e. a step in the value (DIN 1 ->2 ->3) corresponds to a percentage of the scale.

As opposed to ISO, where ISO 100 and ISO 200 are *100* steps, and ISO 400 and ISO 800 are *400* steps apart.

And yes, f-stops are logarithmic and adheres to this, where each step (f1.4 ->f2 ->f2.8) corresponds to a percentage of the scale.

nospam
ask a math professor to explain it to you.

Sandman
Hahahahaha!!!

nospam
that's exactly how he'd react when you try to tell him iso is an arithmetic scale.

Sandman
Here's a fun exercise for you, open a Numbers document and write ISO values and plot them on a diagram:

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Now in the "Axis Scale" popup, change "linear" (arithmetic) to "logarithmic" and see how the Iso scale would look had it been logarithmic.

nospam
apparently you missed where *i'm* the one who suggested graphing it.

i didn't think you actually would, because you've just proven yourself wrong *again*.

notice that when it's set to linear, the graph is a curve and when it's logarithmic it's a straight line. guess what that means.

apparently you don't realize that you've just proven it's a logarithmic scale.

here's a fun exercise for *you*: put f/stops in the next column and then plot that, just as you did with iso. switch between linear and logarithmic, just as you did with iso.

notice any similarities in the graphs?

with linear, both are a curve and with logarithmic, both are a line.

guess what that means. it means that both f/stops and iso are logarithmic scales.

you've not only provided definitions but you proved it by graphing it. good work!