Rosette in HaRGB...

[Hallingskies]

Equipment: ATIK 460EX, Vixen 114mm f5.3 ED114 refractor, NEQ6 mount, guiding with Lodestar X2/PHD

Subframes: 36 x 300s H-alpha, 15 x 200s each for RGB (2x2 binned), flats for H-alpha (same ones rescaled and used on RGB, seemed to work!), hot pixel removal in Astroart (no darks).

My take on the Rosette, processed in Astroart/PaintShop Pro.  Eventually.  I wanted to keep the dusty stuff as dark as possible and to retain the contrasty nebula detail. I was surprised at how large a brightness range the object had, particularly in Ha.  Did think about grabbing some OIII but I think images of this with a bright blue core look weird, so I stuck with what I got over the last two clear nights (in a row!  Clear tonight as well but was home too late to feel like setting it all going - I'll regret being lazy tomorrow).

Just wondered how other non-Pixinsight users blend Ha with RGB data.  

[mikey2000]

That's a stunning view!  I've put off aiming at the Rosette lately as I didn't think it would fit nicely into my view.  But this pic shows how good the tight crop can be.  I really like those dark smokey shadows.

 

As a PI user too, I would love to know how you do the background extraction when there isn't really any background to go on???

[Hallingskies]

44 minutes ago, mikey2000 said:

As a PI user too, I would love to know how you do the background extraction when there isn't really any background to go on???

 

[Hallingskies]

Sorry, I don't use Pixinsight, like I said.  I kno knothing about zis "background extraction".  Sounds painful...

[carastro]

I use photoshop, and I think background extraction means to set balance the colours by clicking on the sky in the image and balancing the colour channels so the background is the correct colour.  This is difficult where there is hardly any background sky to find, but there is usually a small bit to find.  

Quote

Just wondered how other non-Pixinsight users blend Ha with RGB data.  

I have never used PSP so no idea how that works.  But the image looks pretty good, and I love the star colours.  If doing HaLRGB I normally blend the Ha into the Red channel in PS.  If using HaRGB (no luminance) I quite often paste it on top of the RGB as the luminance channel, but it can then take some fiddling to get the colour right.  HTH

Carole 

 

[Hallingskies]

9 hours ago, carastro said:

I use photoshop, and I think background extraction means to set balance the colours by clicking on the sky in the image and balancing the colour channels so the background is the correct colour. 

Carole 

 

Oh right, thanks.  I’m self-taught as no-one has ever written anything up for PSP (maybe I should) but I normally adjust my background in each channel to about the same neutral level (15:15:15) using curves - so that sounds like same thing!  I found it took out the weird green blobs I used to get in dark backgrounds.

Old versions of photoshop are like hen’s teeth (and renting it is a rip-off) and I care not for the jargon that goes with PI.  Over the years I’ve found PSP can do most things that Steve Richards now spells out in his excellent book.

I wonder who else is out there using PSP?

[carastro]

Yes, basically balancing the colours will do it.  

Carole 

[ollypenrice]

I love your Rosette image. Where it's at its best I'd rate it alongside the nicest I've seen. The lighting of the gas has a natural yet contrasty glow which is lovely, as is the colour.

I think there are a couple of issues. Something is happening in the corners, most obviously in the lower right corner, where a flat patch of brownish-red has appeared. It's very artificial because its border is hard edged. I'd be fairly sure that this has crept in during the addition of Ha. Something similar but less obtrusive has affected the other corners too.

I also think the brighter stars are a bit 'hard,' though they're admirably small. I'd be inclined to soften them with a touch of radial blur, or Gaussian if you don't have radial.

In a broadband image an OIII layer won't turn the core bright blue. That's what happens in NB with some palettes. In all probability it will just very gently emphasize the bluer hint of the inner nebula which we can see already.

Olly

[Hallingskies]

Olly: thanks - you are right, the central stars are a bit hard now I look at them. Nothing a bit of selective gaussian blur can’t fix.  See what you mean about the corners, think there may be something in the RGB stack.  Will have another play.

I think one lesson I am learning is that you shouldn’t spend too much time working on the same image - you start not seeing your own self-inflicted artifacts after a while.  Fresh eyes really help.

My crummy suburban skies (and achromatic optics) should really limit me to narrowband but I’ve never been comfortable with the associated colour pallets - they seem so artificial.  Nonsense, of course, because all astro colours are fake, really, but I keep coming back to HaRGB (with a bit of Olll thrown in occasionally) because nebulae “look right” in them, to me, anyway.

Still, if B****t drives me abroad then maybe it’ll be to somewhere with good skies...

[ollypenrice]

1 hour ago, Hallingskies said:

Olly: thanks - you are right, the central stars are a bit hard now I look at them. Nothing a bit of selective gaussian blur can’t fix.  See what you mean about the corners, think there may be something in the RGB stack.  Will have another play.

I think one lesson I am learning is that you shouldn’t spend too much time working on the same image - you start not seeing your own self-inflicted artifacts after a while.  Fresh eyes really help.

My crummy suburban skies (and achromatic optics) should really limit me to narrowband but I’ve never been comfortable with the associated colour pallets - they seem so artificial.  Nonsense, of course, because all astro colours are fake, really, but I keep coming back to HaRGB (with a bit of Olll thrown in occasionally) because nebulae “look right” in them, to me, anyway.

Still, if B****t drives me abroad then maybe it’ll be to somewhere with good skies...

I know what you mean. It pays to save images at various stages and come back to them for comparison. I blink them on and off as layers to see if I've gone astray.

I wouldn't say LRGB produces fake colours. It produces the colours that we would see if we had enormous eyes! That's very different from colour mapping.

Olly

[Hallingskies]

On 26/02/2019 at 12:51, ollypenrice said:

I love your Rosette image. Where it's at its best I'd rate it alongside the nicest I've seen. The lighting of the gas has a natural yet contrasty glow which is lovely, as is the colour.

I think there are a couple of issues. Something is happening in the corners, most obviously in the lower right corner, where a flat patch of brownish-red has appeared. It's very artificial because its border is hard edged. I'd be fairly sure that this has crept in during the addition of Ha. Something similar but less obtrusive has affected the other corners too.

I also think the brighter stars are a bit 'hard,' though they're admirably small. I'd be inclined to soften them with a touch of radial blur, or Gaussian if you don't have radial.

In a broadband image an OIII layer won't turn the core bright blue. That's what happens in NB with some palettes. In all probability it will just very gently emphasize the bluer hint of the inner nebula which we can see already.

Olly

Olly: Thanks for the suggestions, which were spot on.  They were rather obvious errors - I think I had been looking at the screen for too long!  I have now fixed the weird blobby corners (you were right - I had used the "clarify" tool in PSP on the Ha layer, which was a bit of a sledgehammer for upping the contrast.  It didn't actually need it as all it did really was blow the corners out...) and added a slight Guassian blur to the stars to soften them up.  It definitely all looks better for it.  Rather than clutter the forum with iterations of the same thing, I've just updated the image I posted in my blog if you (or anyone else) are interested.

[ollypenrice]

2 hours ago, Hallingskies said:

Olly: Thanks for the suggestions, which were spot on.  They were rather obvious errors - I think I had been looking at the screen for too long!  I have now fixed the weird blobby corners (you were right - I had used the "clarify" tool in PSP on the Ha layer, which was a bit of a sledgehammer for upping the contrast.  It didn't actually need it as all it did really was blow the corners out...) and added a slight Guassian blur to the stars to soften them up.  It definitely all looks better for it.  Rather than clutter the forum with iterations of the same thing, I've just updated the image I posted in my blog if you (or anyone else) are interested.

I followed your link and think the image is even better, but don't worry about putting it on here. I did that with my last image following comments by SGL members.

Olly

[almcl]

On 26/02/2019 at 10:00, Hallingskies said:

Old versions of photoshop are like hen’s teeth (and renting it is a rip-off) and I care not for the jargon that goes with PI.  Over the years I’ve found PSP can do most things that Steve Richards now spells out in his excellent book.

I wonder who else is out there using PSP?

I've just acquired the latest (2019) edition of PSP (having used Corel Photopaint in its various editions for some 30 years).  Heartily agree about 'renting' software, but for less that £50 outright purchase, PSP seemed like a bargain.

Would you be prepared to share your PSP workflow?  Some of my Photopaint experience translates very well into PSP but there are all sorts of new-to-me tools that I haven't quite got to grips with and your experience would be very welcome.

(Very nice image, BTW.)

[Hallingskies]

On 28/02/2019 at 08:05, almcl said:

Would you be prepared to share your PSP workflow?  Some of my Photopaint experience translates very well into PSP but there are all sorts of new-to-me tools that I haven't quite got to grips with and your experience would be very welcome.

Unfortunately I use a very old (v7) version of PSP that bears little comparison to the new one.  One day I will have to get to grips with it.  I believe many of the tools in PSP are similar to those in Adobe however, so I would point you at Steve Richards’s “Black Art” book available from FLO.  

In terms of “workflow” my own limited experience suggests every target is different: tricks that work for some don’t work for others because of differences in star density, contrast and colour.  I normally just do stuff until I get a result I like.  I keep telling myself I should write things down as l often get a good result and then can’t replicate it!

[almcl]

Ah, yes, quite understand!

I was given 'Dark Art or Magic Bullet' for Xmas and managed to replicate the steps (if not always the results) up to about page 112 using Photopaint, which similarly has nearly all the Photoshop tools, albeit under different names.

I was (lazily) hoping someone had managed the same for PSP, but the voyage of discovery will be a good, if steep, learning experience.  I wonder if the 'skin smoothing' adjustment could be made to work on mottled DSLR sky backgrounds...

[Hallingskies]

On 28/02/2019 at 08:05, almcl said:

Would you be prepared to share your PSP workflow?  Some of my Photopaint experience translates very well into PSP but there are all sorts of new-to-me tools that I haven't quite got to grips with and your experience would be very welcome.

 

I use an old version of Paint Shop (v7) but if it helps anyone, I've made a few notes on the "workflow" I used for this image here...

[almcl]

Many thanks for that!

Looking forward to having a play with some of those ideas. 

Not sure about this bit, but my edition of PSP gives an option to include or not the alpha channel when using the tiff format and my (trial) edition of Astro Art 7 seems open  these without a problem?