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Old January 11th 19, 05:00 PM posted to rec.photo.digital
Ken Hart[_4_]
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Posts: 569
Default Finally got to the point where no new camera holds my interest(waiting for specific offering)

On 1/11/19 4:00 AM, Eric Stevens wrote:
On Thu, 10 Jan 2019 23:47:23 -0500, Ron C wrote:

--- snip ---

Reciprocity games. "Introduction to photography 101."

You are still missing the point: lens aperture, shutter speeds or ISOs
are not identical to stops.

At this point my old physics professor would ask for dimensional analysis.
What's the dimensional analysis of "EV" vs "stop" ?


Aah! Some common sense.

Lets have some definitions. Stop is an abreviation of a name for the
aperture of the lens opening. It may be the f-stop or a T-stop (or an
H-Stop.) The fstop is [Image distance]/lens aperture.

I can't properly translate the algebra but you will find it in
https://en.wikipedia.org/wiki/Exposu...xposure_values

It goes something like EV = Log(sub2)*LS/K whe

"N is the relative aperture (f-number)
t is the exposure time ("shutter speed") in seconds[2]
L is the average scene luminance
S is the ISO arithmetic speed
K is the reflected-light meter calibration constant"

It gets more complicated if you want to use T-stops instesad of
f-stops.


And now the "Sunny-16" rule makes perfect sense!

--
Ken Hart