The Dark Shark from Darkest Wales

[tomato]

Well, I'm sure there are darker locations in Wales, but this was from Cwmdu near the Brecon Beacons, at the Autumn Astrocamp. Captured with the RASA8/RC571c on an EQR-6, 26 x 3 mins. Calibrated and stacked in APP, processed in APP, PI, StarTools and AP. It looks like another of my quick grab efforts, but I was planning on getting 8-10 hrs on it over the weekend, but of course the weather didn't co-operate.

Thanks for looking

[Craney]

That's quite something.  Well done.   

You have got blue starlight reflecting amongst the dust. Never been aware of that aspect before.

[scotty38]

Nice image but is it mirror flipped?

[tomato]

Thanks, the orientation is presented just how the subs downloaded from the camera. There were all sorts of fun and games calibrating PHD out in the field, it was too close to the pole to calibrate on target, and the sky further South was cloudy, so had to meridian flip to calibrate then return to Cepheus. 

 

[carastro]

Really nice image but had to stand on my head to see it and then realised it is also flipped.  Somehow l find it very hard to evaluate an image presented in an unusual orientation.
i’d love your skies too.
 

Carole 

[tomato]

Thanks Carole, as this object is circumpolar, I guess it can appear anyway up, as for the flip, is this because of the rather peculiar optical train of the RASA?

Is this more conventional?

[carastro]

Absolutely, thanks.   You even have a feint baby shark underneath, never seen that before. 

Even with my own images l have to rotate them to the regular orientation to he able to process them properly.  There must be a name for this.  
 

Carole

Edited September 28, 2022 by carastro

[ollypenrice]

I love the resolution and depth but, for me, the colour's out of kilter. On my screen the dust is more green* than brown and yet, contrarily, the blues are rather magenta. Too little green in the blues and too much elsewhere seems very odd. Is it just me?

Olly

*Edit. In the sense khaki, really.

Edited September 28, 2022 by ollypenrice
Clarification

[tomato]

Interesting observation, as it was a broadband capture I used Photometric colour calibration in PI but then noted the red channel was not aligned with the blue and green when I moved the image into Affinity Photo. The dust did look too green to me in PI  so I applied a subtle amount of SCNR.

Here is a very quick processing version done with same data out in the field, is the colour rendition better on this one?

[Fegato]

Nice one! 

re: RASA - yes, it always requires a flip. I try and remember to do this straight after integration, but sometimes forget. I was banging my head against the wall with an image a few weeks back which just wouldn't solve in ImageSolver. Realised it wasn't flipped...   as for the "way up" - yes I agree, there is no right way up. It will be different ways up in different parts of the sky, so it's really a personal choice. Why not a diving shark, just to be different!

First image looks OK colour-wise to me - maybe just a hint of greenness in the dust.  I can't see magenta. My monitor is calibrated, so should give a fairly accurate rendition.

Second image looks too pinky red to me, also a bit too bright I think?

 

[ollypenrice]

17 hours ago, tomato said:

Interesting observation, as it was a broadband capture I used Photometric colour calibration in PI but then noted the red channel was not aligned with the blue and green when I moved the image into Affinity Photo. The dust did look too green to me in PI  so I applied a subtle amount of SCNR.

Here is a very quick processing version done with same data out in the field, is the colour rendition better on this one?

Transformed. I don't trust Photometric CC. Sometimes it gives a credible result, sometimes not. I never know why. I think what I'd do now, with this, would be to enhance its local contrasts. In PI that would probably be with Local Histogram Equalization, the idea being to pull out the shark shape.

Olly

[tomato]

Spent a bit more time on the processing, there is so much colour variation in the background, it's hard to know what is the 'correct' rendition.

Anybody know what is causing the apparent 90 degree transitions in the lower left hand quadrant? I haven't deliberately introduced any tool based artefacts in this region.

Edited September 29, 2022 by tomato

[peter shah]

Beautiful job.....not easy this dark stuff....love the last rendition

Edited September 30, 2022 by peter shah

[tomato]

Thanks Peter, I agree the final rendition is the best, but some Magenta hues in the corners.

A good Welsh sky can give Spain a run for it's money if only the clouds would stay away...

[gorann]

Yes, great improvement in the last version Steve! The shark now stands out a bit better from the background. Not sure about the quadrant (or exactly what you mean). In images of this object there is often a dark area all around the shark that makes it stand out. Maybe you did some background procedure initially (like DBE or Gradient Exterminator) that created some oddities in the dust and melted the shark into the dusty sky around it. You can have a look at my RASA version (https://www.astrobin.com/rwtxv1/).

PS, you need to flip the image again😉

 

Edited September 30, 2022 by gorann

[tomato]

Thanks Goran,

 I have annotated the image to indicate where (IMHO) there seem to be some very straight and hence artificial tone transitions in the image, the right angle turns look very suspicious to me also. Maybe it is just my eyes/brain playing tricks.