On Wed, May 22, 2013 at 8:41 PM, Bruce Walker <bruce.wal...@gmail.com> wrote:
> On Wed, May 22, 2013 at 12:24 PM, Ciprian Dorin Craciun
> <ciprian.crac...@gmail.com> wrote:
>> On Wed, May 22, 2013 at 6:21 PM, Charles Robinson <charl...@visi.com> wrote:
>>>
>>> For the K30 (and K5), there is so much exposure latitude that if you're
>>> really worried about oversaturation, just "underexpose" by a stop.. or
>>> two.. or three.. and bring the levels up to what you'd like to see in post.
>>> Job done!
>>
>> The "underexposure" is exactly the problem: in most cases although
>> the JPEG (or the embedded JPEG in the RAW that we see the histogram
>> for) is overexposed, the actual RAW data is under exposed, to the
>> point that almost 25% of the histogram contains nothing.
>
> Since this strange effect only occurs after you tweak the camera
> settings to achieve this elusive UniWB thing, I'd respectfully suggest
> reseting your JPEG settings back to normal.
On the contrary, this effect I've noted is **before** making any
"special" settings, i.e. straight "normal" settings.
> In software development there's a concept of premature optimization
> where the sufferer attempts to optimize perceived bottlenecks at the
> micro-level and fails to step back to look at the big picture. It
> generally comes about when somebody says "That code could be rewritten
> to be faster" when it's not at all clear doing so would actually help
> the system in any measurable way.
Yup, I know about this (I'm in IT too). However the accent in IT
is on "premature", profiling (thus measurement), gains vs development
costs, etc.
In this case it is not premature (because the problem is known,
although not that serious for most people), the measurement is there
(i.e. how much does the in-camera JPEG histogram "look" like the real
histogram, and this can be computed with software), the costs are
marginal (if someone already managed to do it as he can share a
picture with those settings), and the gains are worth it.
(There are also drawbacks, like more time to fiddle in
post-processing, etc.)
> This sounds to me like the camera equivalent for you. That UniWB page
> should come with a warning label that it may lead some folks
> completely astray. :-)
Yup, it does come with that warning label on every page I've seen about it.
> The default histogram is a very useful guide but is by no means a
> precision instrument. If you want more exposure precision get a good
> lightmeter.
I don't think a better light meter (as compared with the in-camera
one) would help much, because UniWB is coupled with ETTR (expose to
the right, i.e. overexpose), thus I don't know how much over-exposure
should I use until I blow everything way over "to the right". :)
Thanks for the feedback,
Ciprian.
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