Probably not an 80A:
http://www.hoyafilter.com/hoya/products/coloredfilters/80a/ ,
more likely 81A:
http://www.hoyafilter.com/hoya/products/coloredfilters/81a/
...Wayne
-----Original Message-----
From: olympus
[mailto:olympus-bounces+wayne.harridge=structuregraphs.com@xxxxxxxxxxxxxxxxx
] On Behalf Of Moose
Sent: Friday, 1 August 2014 2:23 PM
To: Olympus Camera Discussion
Subject: Re: [OM] IMG: Alpaca Farmers, 2
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
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What if the Hokey Pokey *IS* what it's all about?
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