NGC7000 questions.

[Mr Bergman]

 Hi folks!, 

I have now made a reprocess of an image taken a few weeks ago. DSLR, MN190, guided 16x3 min subs. T-shirt flats + darks. Stacked in DSS. Processed in PS. 

I have two questions that maybe some of you can help me answer! 

1) The colours. I have been struggling with colour management since I bought a baader modded camera. Do you think that the colours in this image look alright? 

2) The stars. Taming the big ones have been something new for me. I have used minimum filter and levels on the big ones to keep them as little bloated as possible, but still I got some halos around them. What do you think is acceptable in means of starbloating? I can manage to get stars smaller, but I never manage to get the halos smaller..

Thanks for looking, and please come with criticism! 

Best regards, 

Erik

Link to full image; http://cdn.astrobin.com/images/thumbs/ceb14bd57817b1caf020d42653f99300.1824x0_q100_watermark.jpg

[alan4908]

Hi Erik

I'd say the image looks very good. On the star bloat issue, I also found that this was a problem when post processing NGC7000. I ended up using the Photoshop plug StarShrink by Russ Croman which, when you combine with layer masks, is very effective at shrinking lots of stars simultaneously.

If you want to do the star sharping one star at a time then I also experimented with two Photoshop filters which you might want to try: 

First select the star with a round selection (Elliptical Marquee tool whilst pressing the shift key) then  

1. Filter->Blur-> Radial Blur (for making the stars round).

2. Filter->Distort->Spherise (for reducing the stars).

Alan 

[ollypenrice]

I'd say you have a slight red bias, still. The obscuring dust, when you have enough signal to show it solidly and smoothly, does look very black indeed rather then very dark red as here. At the other end of the brightnesses the stars look a whitish red and the blue stars are not very blue. I don't think you're far out but just a little biased towards red.

A good way to make Ha show well is to go to Selective Colour in Ps and move the top Reds slider to left to lower cyans in red.

I think your stars are fine. Every telescope leaves its own signature on the brighter stars. I did this target recently and just decided to leave them as Mr Takahashi gave them to me. 

https://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-Q4NKT3j/0/X3/NAM%20PELICAN%2014Hrs-X3.jpg

I did do an initial stretch for this with a star mask in place but I always discard these fairly early on the the stretching because they soon become apparent. Still, masking stars in an initial stretch is well worth doing and beats trying to shrink them later.

Olly

[Mr Bergman]

I'd say you have a slight red bias, still. The obscuring dust, when you have enough signal to show it solidly and smoothly, does look very black indeed rather then very dark red as here. At the other end of the brightnesses the stars look a whitish red and the blue stars are not very blue. I don't think you're far out but just a little biased towards red.

A good way to make Ha show well is to go to Selective Colour in Ps and move the top Reds slider to left to lower cyans in red.

I think your stars are fine. Every telescope leaves its own signature on the brighter stars. I did this target recently and just decided to leave them as Mr Takahashi gave them to me. 

https://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-Q4NKT3j/0/X3/NAM%20PELICAN%2014Hrs-X3.jpg

I did do an initial stretch for this with a star mask in place but I always discard these fairly early on the the stretching because they soon become apparent. Still, masking stars in an initial stretch is well worth doing and beats trying to shrink them later.

Olly

 

Thanks for taking time helping me out Olly. Yep, I think you are right about the reds. I will try to adjust it a little bit with the top slider as you said. I find it really hard to get the correct colour balance with my modded dslr though. I need a routine for colour balancing. but not as advanced as using a G2V star. Need to dive into this subject I guess. /Erik

Hi Erik

I'd say the image looks very good. On the star bloat issue, I also found that this was a problem when post processing NGC7000. I ended up using the Photoshop plug StarShrink by Russ Croman which, when you combine with layer masks, is very effective at shrinking lots of stars simultaneously.

If you want to do the star sharping one star at a time then I also experimented with two Photoshop filters which you might want to try: 

First select the star with a round selection (Elliptical Marquee tool whilst pressing the shift key) then  

1. Filter->Blur-> Radial Blur (for making the stars round).

2. Filter->Distort->Spherise (for reducing the stars).

Alan

Alan - thank you! Your ps routine is something new for me. I will absolutely try the spherise filter on the big stars. I also looked into the Russel Croman website but decided to try to learn ps better first before buying more plugins. /Erik

[ollypenrice]

My own colour calibration is really just done by running the colour layer through DBE in Pixinsight. It seems to do an excellent job.

Olly

[Mr Bergman]

My own colour calibration is really just done by running the colour layer through DBE in Pixinsight. It seems to do an excellent job.

Olly

Pixinsight seems to have it all, I have been thinking about buying it, if not just to get DBE... I wish it was a little bit less expensive though. If I look at a 5x5 sample and make the blacks go for about 25/25/25 I still get the red bias.

/Erik