Eric Weir wrote:
On Dec 17, 2017, at 2:08 PM, Larry Colen<l...@red4est.com> wrote:
Note that the greater the dynamic range a camera has, the less apparent
contrast there will be in the unedited file.
You’re gonna have to explain that, Larry. To my naive, uninformed, ignorant
mind it strikes me as counterintuitive. More than a little. But just my naive,
uninformed, ignorant mind.
By the way, a significant portion of my upper division classes in
college were on digital signal processing. A lot of my professional life
has been in computer controls, where we digitize real world data and
work with that. As such, there are a lot of things that I don't even
have to think about like converting number of bits to an equivalent
analog range, so if I mention something as if it is obvious, and it's
not, don't hesitate to ask.
In short....
The K-5 dynamic range at base ISO is basically 14 stops (each bit or
stop is a power of two), that means that it has a range of 1 to 2^14, or
about 16,000 between the least amount that it can register and the
brightest that it can register (for each color channel).
If you have a camera with only 10 stops of dynamic then that is only a
ratio of 1,024.
JPEGs (for example) have 8 bits (coincidentally a bit and a stop each
represent a doubling, or power of two), which is a ratio of 1-256. What
that means is if you map the range of the sensor onto the JPEG, then it
takes 16 times as much change in brightness (contrast) with a 14 bit
sensor to make the same change in 8 bits as it does with a 10 bit sensor.
If you do an HDR in lightroom with two images shot 6-8 stops apart of a
scene with a lot of dynamic range, and you process it without the auto
exposure the resultant image will look very flat and low contrast.
It's something that kind of takes some playing around and
experimentation to get a good feel for.
As to the raw conversion engine, it doesn't really matter what is
running under lightroom, the fact that you do your processing in
lightroom is what I was asking about.
One nice thing about lightroom is that it doesn't make any changes to
the raw file. It stores a set of steps (a recipe, if you will) for the
raw conversion engine, to apply to the raw file to get your final
product. When you make a virtual copy, it just starts off with all of
the settings at whatever point you make the virtual copy and you can
adjust them at that point.
You could go to one of you photos that you've already processed in
lightroom. Press 'D' to get into the develop module, go to the history
on the left, click on "import photo", and that will have all of the
settings zeroed out. Then hit (command or control)-single quote to make
your virtual copy, and that virtual copy is starting out fresh.
--
Larry Colen l...@red4est.com (postbox on min4est) http://red4est.com/lrc
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