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Hello
Tim,
Well,
you made me get off of my duff and work on this image. It is a quick go at
it, but I think it may answer some questions. I shot some short exposures
of Cygnus from Spruce Knob with Provia. I then shot some hydrogen alpha
(Lumicon) through the Pentax 105 at f4 from a moderately light polluted location
on E200. BTW, I did push process the E200 two stops and the grain is
pretty noticeable. I thought I would then use the hydrogen to enhance the
reds in the Provia. I shot for one hour (details on website) on the E200
thru the filter. I did have some significant light pollution
gradients. I had to correct for this and that altered the star brightness
and thus the red color balance of the stars. I then mixed the hydrogen
alpha with the red channel from the Provia to try and maintain the star color
balance in the gradient corrected areas.
That
is one question I have, how to do a color gradient correction in an area without
altering the star color balance? Any help would be greatly
appreciated.
Here
are the links:
The
HydrogenRGB
The
halpha with gradient correction. You can see the star brightness
difference in the upper right.
I
don't have time to post the straight RGB with the Provia. I think you can
do some good work with the hydrogen alpha from a light polluted
environment. Especially if you are going to keep it in black and
white. The gradient corrections are less noticeable compared to when you
try to assign color to the areas. Best wishes and keep us posted.
Nice pictures you posted recently!
Jeff
Ball
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