On 12/20/2019 1:56 PM, Mike Gordon via olympus wrote:
<. . .>
Will tell Marnie ot use current base ISO and expose properly for now, Mike
But - what is proper exposure?
On 12/20/2019 3:13 PM, Wayne Shumaker wrote:
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I often check http://photonstophotos.net/ dynamic range curves. For instance
the E-M5 III peaks at 200, just as Ken mentioned, goes down a bit at 100.
http://photonstophotos.net/Charts/PDR.htm#Olympus%20OM-D%20E-M5%20Mark%20III
When I look at this sort of stuff, I usually wonder, oddly enough, what it means for practical picture making. My
personal conclusion is often "damn little".
For the Raw shooter who is willing to make slight adjustments in post, when necessary, it's simple - set EV = -2/3 and
leave it there, unless you have a really good reason. "The camera makers know what they are doing." is not a good enough
reason. Read Ctein's wonderful essay "Why ISO isn't ISO"
<https://theonlinephotographer.typepad.com/the_online_photographer/2012/09/why-iso-isnt-iso.html> Excerpts*:
"Some photographers chose to continue to "over"-expose their film by one stop to get the extra shadow range and they
were happy to live with a bit less sharpness and more grain. [Present! —Ed.] As always, personal Exposure Indices (E.I.)
count for more than manufacturers' rated speeds."
"*Camera ISO*. There are, god help us, /five/ different industry-standard ways to determine camera ISO. Fortunately,
only one applies to any cameras made in the past five years and works for both JPEG and Raw files and sRGB and Adobe
color space. It's the one that makes the most intuitive sense to photographers, but it's the least physically-based:
Make a bunch of exposures. Process the Raw files into viewable RGB images and decide which exposure produces the best
looking results. Once you know the best exposure for a particular subject luminance, you've got the ISO"
And that's what I've been doing for the last 18+ years with my digicams. The consensus is, and has been for most of that
time, -2/3 EV gives me the best files to work with. That has held true over three DSLRs, at least 11 P&S cameras and a
dozen mirrorless bodies.
You will remember this test shot I've posted before, anent "ISO invariance" But you probably didn't check the exposure.
Yes, it's in a dark room, but exposure is -2/3 EV. I can't expect, or even want, to hold the lights themselves, but I do
want the light stuff next to them not to blow out. <http://www.moosemystic.net/Gallery/tech/GX85/GX85Shadows.htm>
Now, how about some new, mystery examples?
Accidental "underexposure" when I had been shooting out an airplane window and forgot** to change the EV setting from -1
1/3 that evening, indoors, in low light. <http://www.moosemystic.net/Gallery/tech/Misc/CarolDark.htm>
Honestly, I rather like it as shot, although with color correction, but at least with shadows raised a lot less than
this. My point is, this is not a contemporary camera, with claimed ISO invariance, or any such thing.
Any guesses as to when taken and with what camera?
Intentional -1 EV to hold the sky. Again, it would likely look more interesting with the shadows raised less, but this
is a demo. :-)
Any guesses as to when taken and with what camera?
Final addition; With the latest sensors systems, even greater "underexposure" to keep ISOs and noise down, and/or to
hold highlights in high CR situations, works very well, cf. the GX85 example above.
Moose D' Strong Opinion.
* His follow-up, "RAW is not Raw" is also very useful for understanding why someone might choose to vary from the
"official" ISOs.
** I had a good excuse.
--
What if the Hokey Pokey *IS* what it's all about?
--
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