At 12/21/2019 10:39 PM, Moose wrote:
>On 12/20/2019 3:13 PM, Wayne Shumaker wrote:
>><>
>>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".
Pehaps, I still like to know the curve, but I'm not overly obsessed with it. In
the end you do what you need to get the shot.
Cameras now have a built-in mode to take advantage of ISO-invariance. On Sony
it is called DRO - Dynamic range optimization. Basically it under exposes the
image and boosts it back up for the JPEG image output. Other cameras may call
it something else. I have been attempting to find out if it affects RAW files
or not (on the Sony), which I assume it does not, but may explain why I got
poor results using the -EV trick, if the camera is already also deciding to
also do -EV with camera setting: DRO on auto.
Under exposing depends on the camera. Sony tends to preserve highlights better
than some other cameras, so I have not found under exposing to be that much
advantage - often finding there is too much noise in the shadows. I use it when
I need it, but more likely I will just boost the ISO. This is where having 2
more stops on FF vs u43, to me, is an advantage.
Generally, in lower light, the longer you can make an exposure the better the
noise. If you need to dial in negative EV to preserve highlights, that is more
of a camera dependent thing.
What I have been attempting for proper exposure is ETTR - expose to the right.
This requires the histogram be displayed, which can be improved with UniWB, as
the histogram is derived from the JPEG engine. To get better histogram match
for RAW files, getting a unity white balance helps. Jim Kasson has some good
info to get the best histogram:
https://blog.kasson.com/using-in-caera-histograms-for-ettr/
Hence, when attempting to recover the shadows by boosting exposure in post, it
can lead to tonal range loss in the shadows. The image sensor + ADC is linear,
not logarithmic. So the number of bits in the shadow is reduced. This risks
loosing tonal variation, not to mention noise exaggeration. ETTR is an attempt
to make the best of the shadow region without blowing out highlights.
WayneS
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