RE: [APML] NGC 2903 OT

["Greg Hartke" <ghartke@adelphia.net>]

Hi, Tony,

Very cool. Quite lovely. Still love those galaxy pix! I'm particularly
struck by the myriad of faint galaxies in the field. Is this image full
field or cropped? To my eye the stars seem a bit fuzzier than I would
expect, making me think it's only a portion of the full frame. And what's
that near vertical line near the right edge? Looks like an asteroid in the
field.

Your technique is interesting. I don't know why I didn't think of it myself.
If you don't mind, I'm particularly curious to hear what you did to smooth
the image. That's certainly the weakest part of my own processing skills at
this point so I'd appreciate some elucidation. For that matter, if you can
spare a few minutes, some more details of the entire processing operation
would be appreciated as well. It would save me a bunch of time on extra
experimentation.

Thanks and regards,

Greg Hartke
Sykesville, MD USA

-----Original Message-----
From: astro-photo-bounces@seds.org
[mailto:astro-photo-bounces@seds.org]On Behalf Of Tony Hallas
Sent: Sunday, March 21, 2004 10:00 AM
To: Discussion of Film Astrophotography
Subject: [APML] NGC 2903 OT

Hi Guys,

     Feels good to be able to offer something to my old group ... I have
always been intrigued by the strange bar across NGC 2903 so I decided to
take it on ... of note is that I tried out a new system for opening the
image out of 16 bit data ... I only used curves to do this, no levels. It
occurred to me that each time you use levels to attenuate the black point,
you are clipping data ... so I figured out a way to do the same thing only
using curves ... basically you open the image three times ... once to get
the max out of the "dark" data ... this will be a bit noisey and blow out
the highlights, once to open it to the point of smoothness, and once to get
the highlight data. You will use the curves differently each time and then
use layers to seamlessly blend these pieces together, almost like dealing
with an M-42 image. The end result hopefully will be an image that is smooth
but did not have to resort to a smoothing filter of any kind.

      I used the AstroDon filters for the first time ... their claim to fame
is the ability to shoot 1:1:1 RGB ... with only minor tweaking I think the
color came out beautiful IMHO ...

     Not much else to say except that I continue to use PS for all my post
processing with CCD data ... you cannot underestimate the value of having
worked with film to be a successful CCD practitioner ... those of you who
have or will use a CCD will find this foundation essential to photorealistic
results.

     http://www.astrophoto.com/NGC2903.htm

     Have a good one,

          Tony


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