[APML] Revisit of M16/M17

["Jeff Ball" <jeffball@zoominternet.net>]

Hello all,
I wanted to share this as a means of self-instruction and hopefully as a
way of helping others.  The first thing I have been doing on enhancing
is setting or monitoring the black point with eye-droppers at 4
locations on the image.  I then use iterations of levels and curves in
16 bit mode.  The problem with wide-field Milkyway shots is that many
times there is not good point to monitor as black.  I really messed up
the M16 shot by selecting a black point/color balance spot that was
definitely within red nebulosity.  I reviewed the slide again and it was
literally a see of faint red throughout the entire nebula and I had
pretty much obliterated the red in my enhancing.  I revisited and just
tried my best to match the view on the slide.  I came much closer this
time.  That is another think I like about positives, one can sit with
the positive on a light box under a loop and match the enhancement to
what the eye is seeing.  Oh well, here is the redo.  Just wanted to
share some thoughts on this.  I will probably revisit the Cat's paw
area.  That one is giving me some fits as well.  I also rescanned the
image as upon closer inspection I could see the scan was not nearly as
sharp as the positive.  One thing I haven't seen any scanner do well for
our astrophotographs is give us a zoomed in preview to check focus.
Maybe I just don't know how to do this with the Nikon and it is a
feature.  If so, please share the technique.  Thanks.

http://www.astro-photography.com/m16_m17.htm

Jeff Ball
www.astro-photography.com




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