Lukasz Grabun wrote:
>
>> You see I have read advice that you should underexpose to avoid
>> highlights as the underexposed areas can be raised in exposure in
>> post-processing. But "expose right" seems to me to be the opposite ...
>>
>
> When shooting digital it's wise to "expose right" which basically
> means that you should apply as much exposure compensation as possible
> without overexposing the image. More information and reasoning behind
> all this you can find here:
>
> http://www.luminous-landscape.com/tutorials/expose-right.shtml
>
Haven't read that in a long time, so I dont remember what he says, but I
do expose right much of the time. The point is to get the tip of the top
of the histogram to just 'kiss' the end. As a practical matter with most
digital cameras I've used and most subjects, this is more often negative
EV compensation to avoid losing highlights than positive to get them up
to the end. Shooting bright beach, snow and other scenes dominated by
bright subject,will usually require positive EV. And, as I discovered
recently, waterfalls will sometimes need positive EV if they are sunlit.
One problem is that with only an overall luminance histogram on some
cameras, the average will look ok, but one channel will still go over in
some cases. Classic is red flowers, where the average histogram looks
fine, and the red highlight detail is all gone in the resulting image.
And even with separate RGB histograms, they are mighty small and not
totally accurate for that reason. And as Winsor has pointed out, they
are from the JPEG, not the RAW file.
So, one needs to become familiar with the idiosyncrasies of one's own
camera(s) and perhaps tune the internal settings to make the JPEG based
histograms read correctly for your use.
> The same holds true when one shoots negatives.
Here I must disagree. Before going largely digital, I had some time ago
moved from slide to CN film. CN film has wide overexposure latitude, 2-3
stops, and narrower underexposure latitude, 1-1.5 stops.. Once I got a
film scanner, I was simply amazed at the highlight detail in negs that
was not visible in automated prints. The automated printing process
tends to throw away highlights to help reduce the broad dynamic range of
the negs to the narrower one of print paper.
I have found SO many blue skies with white clouds in negs where the
prints simply showed a rather undifferentiated whiteness. Shoot CN for
shadows, if they are important (shoot left). REmember, the shadows are
the thin part of the neg, where it's easier to just run out of silver.
Otherwise, simply go for a good overall exposure. In all but extreme
situations, which are obvious, and rather easily EV corrected, the
highlights will simply be there with normal exposure.
> With diapositives it's the other way around - it's better to underexpose
> slightly.
>
Again, I don't entirely agree. Slide film has too narrow a dynamic range
for many outdoor subjects. The decision whether to over or underexpose,
or stay neutral, depends on which end of the tonal range you least want
to lose. This may most often mean underexposure to retain highlights for
your favored subjects, but isn't a good general rule for everybody and
all subjects.
Moose
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