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Re: [OM] IMG: Alpaca Farmers, 2

Subject: Re: [OM] IMG: Alpaca Farmers, 2
From: Moose <olymoose@xxxxxxxxx>
Date: Thu, 31 Jul 2014 21:22:34 -0700
On 7/20/2014 9:00 AM, Tina Manley wrote:
Yes, I agree.  I can't help but feel that all of the information is there
in the slide if I can just figure out how to use modern software to get it
out!!

Probably not, unless you were using at least an 80A UV filter.

The first part of the problem at high altitude is simple:

1. There is much more UV light.
2. The film/sensor can't distinguish between visible blue and UV light, and 
cheerfully records it all.

So one gets a lot of false blue, which is obvious. But even colors that have 
only a modest blue in the RGB mix are changed.

The second part of the problem is that there is simply no good solution after exposure. It looks too blue, and sort of odd, and perhaps contrasty in an odd way. But since there is absolutely no way to separate 'real' blue from the false blue recording invisible UV, pulling down the blue affects all colors in with any blue in them, each in different ways.

I spent a lot of time on a couple of images from the same area and altitude. With a lot of masking, so the blue could be done differently for different areas and colors, I got something almost natural looking, but not quite. Good enough to pass with most viewers, but what a lot of work!

Interestingly enough, over filtering is better than under. As there is then no UV effect, one may simply pull up the blues until balance is reached. My advice for such altitudes is an 80C filter and some reference shots of neutral targets, so any excess loss of visible blue is easy to correct.

With digital, one may try stronger and weaker filters for any given place and 
light, if there's time to check.

Blue Moose

--
What if the Hokey Pokey *IS* what it's all about?
--
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