The photographer is looking for generalized feedback about the aesthetic and technical qualities of their image.
Description
This is in the northern portion of the Milky Way (hence a lot of star density) next to the Heart Nebula that I posted earlier. We’re having another few clear nights near the dark of the moon – very rare! At Thanksgiving the thing I was grateful for (as a footnote after wonderful family) was that older daughter Annie was hosting this year. If it was us, I would have been too busy to do any astro stuff. I need to check the phase of the moon for future Thanksgivings and Christmases, just in case clear skies might also occur, and we could negotiate.
Specific Feedback
All comments welcome! I’m puzzling about the shade of red. The Heart Nebula next to it, shot a week ago, came out a duskier red. Pixinsight does a sophisticated color calibration based on the actual stars in an image – but we have some light pollution and there was a little moonlight last week – don’t know if that makes any difference… but it sounds like it should be corrected by the star color thing.
Technical Details
Astro rig, about 8 hours of 2-min exposures, calibrated, integrated and processed in Pixinsight. Brought the computer to its knees for hours. Final crop and slight color tweaks in PS – maybe that’s where the red color changed. Will look back at it.
Critique Template
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Great work Diane. I love the density of the stars and especially the subtle blue glow around some of the bigger stars. I don’t really know how to comment on the color. Is there a way to know the true wavelength of the light coming from the nebula, then perhaps you could color correct for that. The sharpness is another impressive feature of this photo.
Good thought. Red emission light is Hydrogen alpha (656.6 nm) and is just within our color sensitivity range. I doubt there is any red shift for the closeby things in our galaxy. But maybe there is some “filtering” effect with interstellar dust? (Could that change color?) But I’m pretty sure the Heart and Soul should match. Both are listed as 7500 light-years away and are almost touching.
A lot of people just tweak colors to taste but I think it’s cool to be somewhat accurate. I just found this on a very long thread about color accuracy in astro imaging.
I’ll adjust both images to that in the morning. The computer is useless right now chugging through last nights capture. Cloudy tonight so I’ll have a day to catch up tomorrow. Then maybe clear 1-2 more nights.
I poked around with the color sampler tool and there is quite a range of reds, none pure red. Maybe the same “dust cloud” whose hydrogen atoms are being excited and emitting red are also being excited enough to emit the H-beta and gamma wavelengths in the chart, and possibly a few other elements being excited in the mix. And the whole thing is being illuminated by embedded stars whose color temps run the gamut from red-orange to blue. So I decided to sample the darkest area and do a curves to neutralize the darks. On this image the channels were within a point, but on the same object shot again last night there was more separation, and neutralizing (by pulling in the dark end of each channel until the matched) gave a slight color cast removal.
So I’ll go with neutralizing darks as best I can and leave the colors to do their own thing.
