From: Greg Harp (gregharp_at_antispamdomain.not)
Date: Wed Nov 26 2003 - 00:08:10 EST
Raoul,
Nice image!
Would you mind sharing the other details of your capture besides the
fact that it was done with the 200mm f/2.8L II and an Astronomik
UHC? (BTW, I'm assuming that's the "PROFI UHC" or is there more
than one version of Astronomik UHC?)
I don't have that filter yet, but it's probably in my future.
Unfortunately, that's probably not going to be soon enough to
capture the Veil this year. At this rate, I'll be lucky to get back
up to the dark skies site before the Veil is too low.
I may try imaging this in town with my IDAS LPS. I've yet to do
much imaging with that filter, as I'm still sorting out so many
other things first. I also have a 48mm Wratten #25A filter that I
plan to stack with it to see what happens.
In my configuration, adding that 48mm filter to the front of the
lens will give me about f/4.5, which will also help the CA issue
that Dennis mentioned.
I'll have to give it a try, next imaging session. I'll report back
how it goes.
In the mean time, I have to try the post-processing approach. The
intent of my post tonight was to get some hints on which way to go,
because as you mention there are just so many approahes.
Fortunately, I installed Photoshop CS a couple of days ago, so I now
have 16-bit layers... Woohoo!
--Greg
--- In digital_astro_.at._yahoogroups.com, "Raoul Schlesser" <gr842_.at._y...>
wrote:
> Greg:
>
> (1) you probably already guessed what I'd be saying :)
>
> but:
>
> try a UHC filter... it works!
>
> I had shown a very similar shot a while back as a test image,
taken with an EF
> 200/2.8 II lens, so very similar to your setup. Only difference is
that I used an
> Astronomik UHC:
>
> http://home.nc.rr.com/rschlesser/Veil_UHC_20031019.jpg
>
>
> (2) you can enhance your image a bit with processing, as you
mentioned. For
> example, in Photoshop, try to make a mask that primarily contains
the
> nebulosity (e.g. copy your image, run it through a median filter
to remove the
> stars, then use curves to stretch the contrast), then enhance the
nebulosity in
> your image using adjustment layers with the mask you just made. Of
course
> there's a number of other, possibly better ways to do this -
anything that
> discriminates between stars and extended nebulosity will help.
>
> However, it's method (1) that really works and that is
more "honest" than (2)
> IMHO. Better yet, keep this image, shoot additional filtered
images, and blend
> filtered and unfiltered - this way you can preserve correct star
colors AND
> show the Veil clearly.
>
> Hope this may give you a few ideas.
>
> raoul
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