Skull and Crossbones Nebula (Sh2-311) in narowband with RGB Stars

Mike Lewis

Mike Lewis

Staff Member
So here is my first version of this target which I finished processing last night and have not yet posted elsewhere other than my own website.

This nebula looks very defiiferent on a deep sky image than visually, which I think account fopr the fact that I cannot see anything resembling a skull and crossbones in here. It is also known by its Sharpless catalog designation of Sh2-311, and as NGC 2467.

This area emission nebula that encapsulates a star forming region in the constellation Puppis. It ius located in the outer reguions of the Milky Way and about 16,000 ly away and is hoome to some very bright, young, and energetic stars.

As always, and feedback is most welcome, and thanks for looking.

LRCC_sRGB_FW_UTIFF_Sh2-311_NB_PSCC_V3_HPF_WithStars-GB-1.jpg



Collection details:

Equipment:
Poseidon-M Camera @ -5C and
Gain:125 Offset:25
Astro-Physics Mach2 Mount
Williams Optics Cat 91 Refractor, 448mm @ f/4.9
Antlia Pro Filters (3nm narrowband plus RGB)
Askar FMA180 Guide scope with ASI290MM

Software:
Pixinsight Commercial Version 1.9
Lightroom CC
Photoshop CC
N.I.N.A. Control Software
BlurXTerminator (Russell Croman)
StarXTerminator (Russell Croman)
NoiseXTerminator (Russell Croman)
Astro-Physics APCC and APPM

Light Frames:
Gain 125 / Offset 25
Hα: 24 x 900 secs (6 hrs)
Oiii: 19 x 900 secs (4 hrs 45 mins)
Sii:: 19 x 900 secs (4 hrs 45 mins)
Red: 22 x 60 secs (22 mins)
Green: 18 x 60 secs (18 mins)
Blue: 15 x 60 secs (15 mins)

16 hrs 25 mins total

Dark Frames:
10 x 60 secs (10 mins)
10 x 900 secs (2 hrs 30 mins)
 
JimFox

JimFox

Moderator
Staff member
Super cool Mike! As always its a great honor that you post your astro images here first.

I sure like Skull and Crossbones. I don't believe I have ever captured it. It's a fun looking one for sure.

Overall I like what I see in this, the shapes the details the colors. But my very first impression comes from a look I see in regular images where there was too much highlight recovery. When Highlight recovery is done too much, it can give the area a kind of gray tone and also mute the colors and light so that the area loses depth.

This might be too picky on my part. But in the object, I think it needs to be brightened slightly, while protecting the 2 areas in it that are pretty bright and would blow out if brightened more. Specificially I think the blue OIII areas (except for the upper right) could use to be a bit brighter to increase the depth that should be there.

As a suggestion, I would mask the OIII in it, and then in Photoshop/Lightroom use the Shadow Recovery first to see if 3 to 4% pops the OIII a bit more without losing contrast in it or blowing out the brighter area. If that doesn't work, I know you have lot's of ways to accomplish the same idea.
 
AlanLichty

AlanLichty

Moderator
When I first opened this thread my first thought was "where are the skull and crossbones?" and then I read your prose. Neat looking nebula with some nice details and colors.
 
Mike Lewis

Mike Lewis

Staff Member
JimFox said:
Super cool Mike! As always its a great honor that you post your astro images here first.

I sure like Skull and Crossbones. I don't believe I have ever captured it. It's a fun looking one for sure.

Overall I like what I see in this, the shapes the details the colors. But my very first impression comes from a look I see in regular images where there was too much highlight recovery. When Highlight recovery is done too much, it can give the area a kind of gray tone and also mute the colors and light so that the area loses depth.

This might be too picky on my part. But in the object, I think it needs to be brightened slightly, while protecting the 2 areas in it that are pretty bright and would blow out if brightened more. Specificially I think the blue OIII areas (except for the upper right) could use to be a bit brighter to increase the depth that should be there.

As a suggestion, I would mask the OIII in it, and then in Photoshop/Lightroom use the Shadow Recovery first to see if 3 to 4% pops the OIII a bit more without losing contrast in it or blowing out the brighter area. If that doesn't work, I know you have lot's of ways to accomplish the same idea.
Click to expand...
Thanks Jim for the detailed feedback. I have a few other things I may try with this, and I will add some subtle work on the Oiii levels to the list. As you say there are some regions that are brighter that will not display well uinless care is taken to mask those areas off to not be adjusted. In the case of this version I actually took the stretching down a bit on this version from a previous one, exactly because I was losing definition in somew areas. As you well know, it is often a balancing act with this stuff...

ML
 
Mike Lewis

Mike Lewis

Staff Member
AlanLichty said:
When I first opened this thread my first thought was "where are the skull and crossbones?" and then I read your prose. Neat looking nebula with some nice details and colors.
Click to expand...
Alan,

Yes, how is this a skull and crossbones? As I mentioned above, the name is perhaps from times where it was seen visually or imaged on film when the ability to bring out the faint regions did not exist to the level it does today and perhaps in that guise it looks like a skull and crossbones? Just a guess on my part...Thank you for your kind comments on the image!

ML
 
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