On 12/22/2019 5:03 PM, Wayne Shumaker wrote:
At 12/21/2019 10:39 PM, Moose wrote:
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".
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.
That is only one part of it. According to A7 II Manual:
"[D-Range Opt.]: By dividing the image into small areas, the camera
analyses the contrast of light and shadow between the subject and the
background, and produces an image with the optimal brightness and
gradation."
That says to me that it may not be just an overall adjustment? Or is aggregating by small area just to make the final
calculation less onerous for the processor? Who knows. My answer is just D-Range Opt Out.
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.
According to this site,
<https://photo.stackexchange.com/questions/80115/what-exactly-does-dro-do-and-how-does-it-work>
"DRO is one of the few settings which indirectly impacts RAW files. While its designed as processing, which normally
effects JPEG and TIFF files only, the camera adjusts exposure to have more dynamic range available for the mapping,
often reducing exposure to get more details in highlights. If you shoot RAW and Manual mode though, DRO will have no
effect."
It looks to me as though this effect may hold true for LVx settings, as well as
Auto.
In any case, it appears that you may indeed suffer from double EV dipping when using DRO. I have DRO set off, as I only
shoot Raw. It seems that one might use one or the other, but not both.
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.
I was doing that before ETTR became a popular idea. Then ETTR became OUT. I don't recall why, but one risked not being
heard if people reacted negatively to the acronym. I've gone right on doing what I might call ETRH (Exposure to Retain
Highlights) :-)
A problem/advantage of the web is that many things never go away. The problem with the blog entry below is that it is
seven years old. Sensor tech has moved on, and some of the generalizations no longer apply to at least some more recent
sensor systems.
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/
Too fussy for me. Just set EV to - 2/3 for the vast majority of shots, and
Don't worry, be Happy!
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,
Yeah, words that are logically true, with conclusions that aren't borne out in
practice, at least mine with recent sensors.
not to mention noise exaggeration.
Per my reply to your 11/3 posts a few minutes ago, the excessive noise you are fighting is an artifact of processing
protocol. Fix that, and you may be a lot happier.
Hold Onto Highlights Moose
--
What if the Hokey Pokey *IS* what it's all about?
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