Again, I managed to demonstrate my provincial ignorance. I guess I didn't
realize them mountains down there wuz that high.
But, yes, the altitude blues can be a problem, and even with our diminutive and
puny mountains here in the Southeast, where the highest peak is just over 6500
feet, I prefer the B+W KR3 to the paler and less effective 81A. But with
digital, curing the Smoky Mountain blues is no problem in post processing.
Apparently, at the 12,000-foot elevation of the Bolivian mountains where
Richard is going, that's not possible, and a more potent filter, like an 81B,
maybe even an 81C, might be in order.
And it could be that it's something neither filters nor post processing can
correct anyway, because those folks down there may actually be blue -- possibly
because they can't get HBO and have to wait on the missionaries to tell them
what's going on in Deadwood right now.
Forgive me, Richard. I know you do good work down there, but I couldn't resist
the smart-ass HBO comment, because, you know, I'm a smart-ass. Always have
been. It's apparently hereditary, because my parents were both smart asses,
and so are all my children. The grandkids are in training. :-)
Walt
--
"Anything more than 500 yards from
the car just isn't photogenic." --
Edward Weston
-------------- Original message ----------------------
From: Moose <olymoose@xxxxxxxxx>
> Walt Wayman wrote:
> > But to the point: Why not just make the correction in post processing. The
> effects of an 81A filter should be easy enough. I've got bunches and bunches
> of
> filters, but I don't use any, except polarizers, for digital since it's so
> easy
> to mimic the effects in either PWP or PS.
> >
> The 81 series are one of two types of filters whose effect cannot be
> fully duplicated in post. The other one is, of course, the polarizer and
> its ability to control reflections.
>
> At any altitude reachable in Georgia, and indeed the East Coast, you are
> correct. At the altitudes Wayne shoots at in the Bolivian Andes, UV is
> very high level. The problem is that the blue sensors in the camera or
> film can't differentiate between UV and visible blue light. So when you
> correct the excessive blue in some parts of the subject, it throws off
> the color balance in the other parts.
>
> Some shots can be corrected nicely in post. Others, even with masking of
> different areas of the image, can be very difficult to make natural
> looking. I tried that on a couple of Wayne's images when he first posted
> some from Bolivia with problems a few years ago. After all those
> discussions, he started using 81 series filters, which nicely fixed the
> problem.
>
> Interestingly, if one is always going to post process ones images, it's
> better to use too strong an 81 filter than not strong enough. Over
> filtering makes sure there is no UV effect and the other color balance
> problem is easy to correct.
>
> I've just looked at the lens on the F30. What I would do is buy some 81
> a or b gel filter(s), cut out appropriate sized circles and carry a
> little baggie of them and a roll of double stick tape. The gels are
> cheap and each piece should be usable several times. There is a big
> enough circle of metal surrounding the actual lens opening to do this in
> a way that won't interfere with the lens opening and closing.
>
> If one happens to be left on for an indoor or other shot, flash or not,
> where it over warms it can easily be corrected in an editor.
>
> Moose
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