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Re: M16 H-alpha Color vs. Luminance and Interesting Artifact

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  • dennis_persyk
    Hi Larry, Thanks for the input. In my poll, the B&W is winning. While the information content of a color image is far greater than B&W, my H-a image is
    Message 1 of 4 , Jul 7, 2010
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      Hi Larry,

      Thanks for the input. In my poll, the B&W is winning.

      While the information content of a color image is far greater than B&W, my H-a image is psuedo-color and monochrome. I've taken a few HaLRGB images to get "real" color, but I just don't have the patience to change all those filters (I don't have a filter wheel, much less a computerized one) and spend the greatly increased time in acquiring and processing the five sets of images. I'll leave that to the experts. I just enjoy creating moderately pretty pictures -- and imaging comets, of which there are currently few that I can image :) I am pretty much stuck with imaging emission nebulae via a narrow band filter due to my high level of light pollution at my site 40 miles west of Chicago.

      I think the real problem with my colorized version is that it is clipped and the black point is too far towards zero. I use Neil Carboni's Actions in Photoshop and I literally just push a button and out pops a nicely colorized image. Unfortunately I don't have the skill to tweak the process so I have to accept what the computer produces.

      My 11-inch Celestron SCT visual scope is gathering dust in the observatory because even the simplest cameras capture far more detail than the human eye. But my neighbors enjoy the views so I guess I'll keep it.

      Clear skies,
      Dennis


      --- In sct-user@yahoogroups.com, "elwaine" <lwdmd1@...> wrote:
      >
      > Dennis - first of all, the image is Spectacular!
      >
      > To answer your question about colorized vs. B&W, I prefer the B&W rendition, even though the colorized picture is initially the most visually striking. The reason I prefer the B&W image is because fine details are just plan easier for me to spot in the B&W photo. There is nothing that I see in the B&W that I cannot detect in the color image, but I find that I have to really search for the finer details in the color image whereas they stand out a little better in the B&W.
      >
      > I am curious about the differences I see in the red image vs. the B&W; and since our eyes are more sensitive to green light, I wonder if subtle details would become more easily apparent if you had chosen green instead of red... even though green might result in an overall ghastly appearance.
      >
      > Regards,
      >
      > Larry
      >
      > --- In sct-user@yahoogroups.com, "dennis_persyk" <dpersyk@> wrote:
      > >
      > > My web page liked below has the following:
      > >
      > > 1) Colorized and Luminance images -- which do you like and why?
      > >
      > > 2) "Marching hot pixels" artifact unique to long H-a stacks when mount is not precisely polar aligned
      > >
      > > 3) Eyepiece view of what M16 looked like to my old eyes in the 11-inch SCT with an Orion SkyGlow light pollution filter
      > >
      > > 4) Five second 4x4 binned H-a centering frame illustrating the 16-fold increase in sensitivity afforded by on-chip pre-readout binning
      > >
      > > 5) SkyMap Pro screen shot of M16 location
      > >
      > > I hope there is something in the above list that will interest you at
      > > http://users.FoxValley.net/~dpersyk/new.htm Please take a look.
      > >
      > > I do mainly H-a imaging now because my 6 nm FWHM AstroDon is a very effective light pollution filter. And of course, it works well with moonlight.
      > >
      > > Clear skies,
      > >
      > > Dennis Persyk
      > >
      > > Igloo Observatory (now actually a roll-off) Home Page http://users.FoxValley.net/~dpersyk
      > > Hampshire, IL
      > > New Images http://usersFoxValley.net/~dpersyk/new.htm
      > > Pier Design Paper http://users.FoxValley.net/~dpersyk/Pier_Design.htm
      > >
      >
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