Second part of the "trilogy" on the Sh2-132. This image, in addition, is the first one I am posting with the ASI-183MM, that I bought second-hand last spring. Very happy with it, superb "bang for the buck" (well, euro), I bought it to combine it with the samyang/rokinon 135mm, and any future short focal that may come, considering the extremely small pixel size. My feeling is that it pairs up with the 135mm very well. It is true that it has a severe amp-glow, but it calibrates out well.
So, the combination provides a sweet wide field, not as wide as with the canon (6.4 pixel), but I prefer it like this one, as most of the objects get better depicted in the wide field, and not so small/under-resolved.The resolution obtained for the wide-field is, in my opinion, wonderful. I was amazed of how many great objects are nicely captured across the image (mostly planetary nebulae and clusters, check the full version). Given the "funkiness" of the palette, the planetary nebula are mostly green :-) (specially nice are PK103+001 and PK102-02.1)
On the processing, I wanted a different result from the
closer one. I tested several narrowband alternatives (SHO, HOO, SOH,...), and still the ones I was liking the most were variations from the SHO. So I decided not to wipe completely off the green cast, and shift a bit its hue to produce my "funky lion".
The total processing time is per channel:
Ha = 88 x 600s
Oiii = 103 x 600s
Sii= 75 x 600s
The followed process has been:
1) cropping and DBE. Very soft Multiscale linear transform for noise reduction
2) two "lanes" of stretching:
- a) Stars lane
- 2.a.1) combine with pixelmath : R=0.8*S+0.2*H G=0.9*H+0.1*O B=0.9*O+0.1*H. SCNR of green cast.
- 2.a.2) stretching = soft masked stretched (default value)
- 2.a.3) application of StarXterminator to extract nicely tight and color stars. Produce also a mask out of them.
- B) backgound lane
- b.1) combine the backgorund channels with pixelmath : R=0.6*S+0.4*H G=1*H B=1*O . Hue shift in the green tones . Partial SCNR on green
[*]- b.2) Histogram Transformation (until the curve cuts the second vertical line, about 25%)) of each channel
[*]- b.3) application of StarXterminator. Use the more bloated stars as an inveser mask to fill with little noise (uniform) the "holes" left by the starxterminator on some stars, in order to make all background homogeneous.
- b.4) combine the background channels with pixelmath : R=0.8*S+0.2*H G=0.9*H+0.1*O B=0.9*O+0.1*H.
- b.5) application of noise reduction
3) application of stars to the background using the star masks as a filter (application with pixel math) ($T (masked)+ stars)
4) stars color and bright adjustments
5) final levels in lightroom and some cosmetic touches.
Hope you like it! Take care!
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