On 1/28/2012 7:07 PM, Paul Stenquist wrote:
On Jan 28, 2012, at 9:49 PM, Larry Colen wrote:
On 1/28/2012 6:29 PM, Paul Stenquist wrote:
You can "expose to the right" or anywhere you choose by using exposure comp in
any metering mode. The metering isn't based on jpeg or RAW. It's based on the light and
what's in front of the lens. No meter is smarter than a photographer who understands how
meters work.
I'm certain that if I'm wrong someone will correct me. The metering mode in
our cameras picks a spot to meter on, and sets the exposure for that point at
midpoint. This means that if you look at the histogram, you usually get a bell
curve right around the middle of the graph, expose to the middle. This means
that if you go direct from RAW to JPEG without any compensation in post
processing, most of the pixels in the photo will be right around the midpoint
of exposure.
No. In multi mode, the meter uses a program to analyze the scene and tries to
achieve a balance of highs and lows. If you don't like the histogram that
results, you can move it right or left with exposure comp. You only get a bell
curve in the middle when you have an average scene without extreme highs or
lwows.
Interesting. Then why is it that if you photograph something like a
white table, or snow, using normal metering, it comes out grey rather
than white?
So, what you are telling me is that the metering in our cameras is
optimized to give the best performance when shooting in raw mode, rather
than in jpeg?
Or, that unlike in film where you'd meter differently for negatives and
slides, there is no difference in metering for getting the best exposure
out of jpegs and out of raw?
What it does not do is look at the pixels out at the tail end of that graph.
If a bunch of them are off to the right, and you expose for the middle, then
you end up clipping on a lot of your readings, in other words, you'll lose
highlight detail.
Then you bring that back in by dialing in negative exposure comp.
Alternatively, if most of the readings are to the left of the point that is
metered for, then exposing for the middle will leave you with either a lot of
pixels that are clipped black, or a lot of your shadow detail lost in the noise.
Then you dial in positive exposure comp. Simple.
Why not have a mode in the camera that does it automatically? Give me
the source code for the K-5 and I could probably implement it in a week.
The principle of exposing to the right has nothing to do with where you put the
peak of that bell curve, but that you expose the picture as much as you can
without clipping details in the highlights. In the first case, this will reduce
the exposure on the fat point of the graph, giving you a bit more noise, but
you won't lose information in the highlights.
In the second case, you expose everything a bit more, then when you compensate
in post production, the noise gets reduced along with everything else,
improving your signal to noise ratio. Not entirely unlike how Dolby noise
reduction works, apart from Dolby being on an analog signal, and only in
certain frequency ranges, but still, amplify everything, signal and noise, and
then when you reduce everything, the noise is reduced.
Perhaps, I'm missing something, butI don't know what you men by choosing 18
percent gray for shooting jpegs. You can use the spot meter and take gray card
readings if you want a pure 18 percent gray exposure read. A histogram based on
the raw might be nice, but it's not hard to interpret a jpeg histogram in terms
of where you'll be with RAW. If you're edge to edge with jpeg, you're pretty
much golden with RAW, and if necessary, you can push it beyond that a bit.
Paul
On Jan 28, 2012, at 8:58 PM, Larry Colen wrote:
Never mind raw on a point and shoot, I want my DSLR to properly support shooting in raw.
I want metering and histograms based on the raw data. I want to choose metering modes so
I can use "expose to the right" for raw, and if I want to shoot jpeg I can
choose 18% grey, or whatever they call it.
For doing landscape and studio work, I fantasize about a mode that will take a
test shot (or three), examine the raw data and set the exposure for details in
the highlights or the shadows, or the bracketing for an HDR series of exposures
that will cover the full tonal range. I want a TAv mode for the green button
in M, so that I can set the shutter speed and aperture based on a critical
element of the photo, have it set the ISO, and then just leave it there.
Everything about using my camera indicates that raw is an afterthought, and the
UI is optimized for people that want a $1,000 point and shoot with
interchangeable lenses.
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Larry Colen l...@red4est.com (from dos4est)
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