M17 Color

[Rowland]

Ken. Suggest you try Regim first. I don't use DSS for the reasons stated here and elsewhere.

http://www.andreasroerig.de/regim/regim_e.htm

Regim settings http://forum.startools.org/viewtopic.ph ... t=10#p3138 these should work.

[FishLocator]

I am still a beginner, no doubt. But recently I took some DSLR images of the Swan Nebula and they look very similar to yours. I have not processed them to final images yet, but the individual frames all have a bluish hue in the center of the swan. I know people take all kinds of artistic liberty and process their images in different ways.

http://apod.nasa.gov/apod/ap120506.html

[Rowland]

Ken.

The CR2 files converted nicely to tiff files using the options suggested and debayered without problem in PixInsight - I've attached some screen shots.

Interestingly 2 frames would not register/align and these were left out of the stack. No scaling was applied to the integration process. Image weights applied to the stack all came in very close to 1. The top image is the temporarily stretched linear stacked image.

The final image is a very basic run through ST. At 60 seconds per sub, and without calibration frames, the noise is very high. Ignore that. The real gem here is data retention. With substantially more subs and calibration frames the detail will pop. Quite deliberately I have used the scientific colour module and made no attempt to fix the background - I want to see the nebulosity - I don't don't care about darkening the background and loosing that wonderful wispy nebula.

Some acquisition pointers, of which I am sure you are aware. Your scope might benefit from an aperture mask to reduce the coma in the corners. A bit of circular cardboard with a hole in the middle. Perhaps longer exposures as well or many many more. Total time is the goal.

Not sure what's happening with DSS. As suggested try Regim and see what you get. While preprocessing was done in PixInsight no special parameters were applied.

The finished image is in the next post - no room in this one.

[Rowland]

Processed in ST - I have included the log for what its worth. Ivo might want to move this to image trouble shooting.

The blue core is typical of an unmodified camera and not an issue (maybe - just to avoid contention). The main game is acquisition technique and sane preprocessing. Once these are sorted out the rest is icing on the cake.

Code: Select all

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StarTools 1.4.302
Wed Jul  1 10:59:28 2015
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File loaded [/home/geoland/Downloads/12-10-15 M17/KenM17.tiff].
--- 
--- Bin
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [Off]
Parameter [Outside ROI Influence] set to [15 %]
--- Crop
Parameter [X1] set to [134 pixels]
Parameter [Y1] set to [105 pixels]
Parameter [X2] set to [2434 pixels (-167)]
Parameter [Y2] set to [1625 pixels (-107)]
--- Develop
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [1.00]
Parameter [Skyglow] set to [0 %]
Parameter [Digital Development] set to [94.12 %]
Parameter [Blue Luminance Contrib.] set to [100 %]
Parameter [Green Luminance Contrib.] set to [100 %]
Parameter [Red Luminance Contrib.] set to [100 %]
Parameter [Dark Anomaly Headroom] set to [5 %]
Parameter [Dark Anomaly Filter] set to [9.0 pixels]
--- Wipe
Parameter [Mode] set to [Correct Color & Brightness]
Parameter [UNKNOWN] set to [Yes]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [2 pixels]
Parameter [Drop Off Point] set to [0 %]
Parameter [Corner Aggressiveness] set to [100 %]
Parameter [Aggressiveness] set to [85 %]
--- Develop
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [1.00]
Parameter [Skyglow] set to [0 %]
Parameter [Digital Development] set to [94.41 %]
Parameter [Blue Luminance Contrib.] set to [100 %]
Parameter [Green Luminance Contrib.] set to [100 %]
Parameter [Red Luminance Contrib.] set to [100 %]
Parameter [Dark Anomaly Headroom] set to [5 %]
Parameter [Dark Anomaly Filter] set to [Off]
--- Color
Parameter [Cap Green] set to [To Yellow]
Parameter [Bias Slider Mode] set to [Sliders Reduce Color Bias]
Parameter [Style] set to [Scientific (Color Constancy)]
Parameter [LRGB Method Emulation] set to [Straight CIELab Luminance Retention]
Parameter [Dark Saturation] set to [2.00]
Parameter [Bright Saturation] set to [Full]
Parameter [Saturation Amount] set to [200 %]
Parameter [Blue Bias Reduce] set to [1.09]
Parameter [Green Bias Reduce] set to [1.45]
Parameter [Red Bias Reduce] set to [1.00]
Parameter [Mask Fuzz] set to [1.0 pixels]
--- Wavelet De-Noise
Parameter [Scale 1] set to [90 %]
Parameter [Scale 2] set to [90 %]
Parameter [Scale 3] set to [90 %]
Parameter [Scale 4] set to [90 %]
Parameter [Scale 5] set to [0 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Scale Correlation] set to [6]
Parameter [Color Detail Loss] set to [12 %]
Parameter [Brightness Detail Loss] set to [12 %]
Parameter [Grain Size] set to [5.0 pixels]
Parameter [Read Noise Compensation] set to [1.60 %]
Parameter [Smoothness] set to [75 %]
--- Wavelet Sharpen
Parameter [Intelligent Enhance] set to [Yes]
Parameter [Scale 1] set to [100 %]
Parameter [Scale 2] set to [100 %]
Parameter [Scale 3] set to [100 %]
Parameter [Scale 4] set to [100 %]
Parameter [Scale 5] set to [100 %]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Amount] set to [25 %]
Parameter [Small Detail Bias] set to [75 %]
Undo.
Redo.
Undo.
Redo.

[midwayexpress]

Hmm I don't know if is a unmodded camera issue or not. I took this with a unmodded T3 a couple years and mine was pretty red even in the core.

What kind of telescope was this taken with? Was it an acromat?

[Rowland]

Hmm I don't know if is a unmodded camera issue or not. I took this with a unmodded T3 a couple years and mine was pretty red even in the core.

What kind of telescope was this taken with? Was it an acromat?

That's my guess. The spikes on the bright stars tend to suggest a reflector

[Stargazer_Ken]

Ha! Hadn't noticed this went to a second page!

This is an 8 inch F4.5 dob on a Celestron CGEM mount. Mediocre tracking. Have to work on auto guiding it some day if it will take the weight. Thinking of getting a Baader MPCC coma corrector to clean up the corners. May have some flats around I can use... These photos were taken back in 2012 and I didn't take darks.

Thanks everyone,
Ken

[admin]

Hey guys,

Ken, thanks for poking me via email - I’ve been having trouble lately keeping track of all the goings on on the forum...

The blue in the Swan nebula is very real!

It's the reflected light of hundreds of extremely bright O and B class young blue giants, who are at the same time, 'blowing' away (and exciting) the purplish/pink emitting hydrogen gas, from which they were born, in the progress.

In fact, blueish areas are a common feature of HII areas, given the above process that takes place within them (that's so cool about the Color Constancy feature - it reveals all the different colors and hence possible processes going on).

Hints of it are visible in many other HII areas such as the Rosette and, of course, the Orion Nebula. Let this process go on long enough and the end result is a nebula that is stripped of its hydrogen emissions and is solely reflective, like the Pleiades.

You've captured all this with a modest DSLR. How cool is that?