Crab Nebula HA-LRGB Burning like fire

[pyrasanth]

I took a closer look at the Crab Nebula data I took earlier & deconvolved each of the channels. I then produced an HA LRGB hybrid & smart sharpened 30% in Photoshop. The result is quite good but instead of me blowing my own trumpet let me know what you think. I am going to get more data next season as the Crab is getting a bit low now. The 70 mins of HA data makes the nebula burn like a match!

 

 

[kendg]

Yes it does burn like a match. Great image. 

[swag72]

I like the M1, I think it's come out really well - Well done

For me, the continual killer for me with your images is the background and the stars. The stars look so crunchy and there's nothing by way of softness about them. They also look like they have been reduced to an inch of their lives just leaving small one pixel dots. To my mind that's not how stars look.. they are different sizes and intensities in reality ..... not here. I'd love to see something from you that hasn't been processed much.... my general thoughts at the moment is that you are over processing, certainly the background and stars.

The M1 is good though..... and I hope that my comments don't take away from that

[pyrasanth]

10 minutes ago, swag72 said:

I like the M1, I think it's come out really well - Well done

For me, the continual killer for me with your images is the background and the stars. The stars look so crunchy and there's nothing by way of softness about them. They also look like they have been reduced to an inch of their lives just leaving small one pixel dots. To my mind that's not how stars look.. they are different sizes and intensities in reality ..... not here. I'd love to see something from you that hasn't been processed much.... my general thoughts at the moment is that you are over processing, certainly the background and stars.

The M1 is good though..... and I hope that my comments don't take away from that

I understand your observation. The difficulty I face is that my imaging area is very light polluted so the gradients can be heavy if I don't  darken the sky. GradientXterminator helps. I can easily rework the image so the stars are as seen. I will give it a try & then look for your observations on how the image appears. The other difficulty with the Schmidt cassegrain is the bloated stars so they can get quite bloated but again I think less enthusiasm with StarShrink might be good. I'm not in any way critical of your observations but the raw data I'm working with is sometimes very poor. Take a look at the stretched image below:

 

 

[laudropb]

Very nice image. Lovely detail in the nebula

[pyrasanth]

A less aggressive image is posted below:

This has been done on a dual layer with the stars processed separately as the HA integration into the nebula gave the stars a very unnatural colour.

 

[PeterCPC]

Very nice image.

Peter

[Daniel-K]

On 24/03/2016 at 08:09, pyrasanth said:

I understand your observation. The difficulty I face is that my imaging area is very light polluted so the gradients can be heavy if I don't  darken the sky. GradientXterminator helps. I can easily rework the image so the stars are as seen. I will give it a try & then look for your observations on how the image appears. The other difficulty with the Schmidt cassegrain is the bloated stars so they can get quite bloated but again I think less enthusiasm with StarShrink might be good. I'm not in any way critical of your observations but the raw data I'm working with is sometimes very poor. Take a look at the stretched image below:

 

 

Hummm i remember having this on my 500D it was the way DSS was stacking them. Try a different method. Flats darks and bias will really help if your not already doing them.

[gorann]

The nebula in you first image is amazing, but Sara is clearly right about the stars. The nebula is obviously better in the first version. I would use layer masks is PS to merge the two, using the stars from the second one.

[ollypenrice]

Sara's comment exactly expressed my own feelings. Softly softly, for me, on background sky and stars - and certainly no deconvolution on them.

The nebula in version one is, in many ways, stunning.  To push the processing as hard as you have, though, and for it to look 'invisible,' I think you would need at least twice the data. If you were to ease off on the sharpening (by whatever name) I think you'd get a more natural look with what you have.

You've done a mighty fine job of the LP though. Hats off.

I've just been back up for another look at the Mk1 nebula and, yes, it's quite a result!

Olly

PS You might find DBE in Pixinsight a boon. For me it is a long way ahead of the competition in gradient removal. In other respects I'm 'very Photoshop.'

[gorann]

I took the liberty of mixing your two versions using layer masks in PS. Hope you do not mind.

[pyrasanth]

54 minutes ago, gorann said:

I took the liberty of mixing your two versions using layer masks in PS. Hope you do not mind.

Not at all- go for it- looks really good. I think the background stars need to be more dynamic- what do you think. I can go back to the original material & see what I can do but it gives us an idea as to how the image could look.

[gnomus]

Firstly M1 itself looks quite stunning.  Secondly, that is an awful gradient in the (?double cluster) image.  To be able to dig the image you have out of that is quite something.  

The background is a little too dark for my taste but I understand why you have done it with the gradient you have. 

[pyrasanth]

I took the advice of everybody & combined the 2 images & did not sharpen the stars. We get the image below- I think it's finally finished but let me know- Olly could have more good advice to give it a few more tweaks. But, I think it's okay as its the best of the advice you guys gave me.

 

 

[gorann]

You do have some colour on some stars, and you also have quite a few small faint ones, but if there are more colours in the stars you could try to dig it out. Instead of having to do the whole image from start (must be a terrible job with the gradients you have), you could make a version with colourful stars but terrible gradients and then just use layers to selectively bring out the stars you want one by one using the brush tool in PS. Most will probably be quite white so no need to bring them out. By the way, when I used the background of your second image, I first did some gaussian blurr to get rid of the rather strong noise and then sharpened the stars a bit (using the unsharp mask filter) and finally shrunk them 1 pixel.

[gorann]

PS. I think the background is about right in darkness. The eyedropper tool in PS tells me that your background is 25-30 on all three channels, which is what some tutorials suggest to be a good level. Your histogram looks ok too and does not suggest clipping.

[gnomus]

I think its much better.  There are one or two darker haloes around some of the stars.  I wonder if you could reduce the impact of these.  I hope you don't mind but I had a few minutes playing around with curves and then the dodge tool:

[gorann]

It is on its way to become a stunning image. Gnomus, it also looks like you reduced background noise, nice. Pyrasanth, you obviously caught so much detail in the nebula that we SGLsers cannot keep away from it.

Now, there is some annoying noise in nebula. I think it could be fixed by some blurring the nebula and then using layer masks to sharpen the contrasty parts, maybe using the first version you posted here.

[ollypenrice]

Heheh, it really is getting there! Some very fine grained NR might help but, really, just going a bit easier on the stretch at the outset would be the best way. I'm not surprized this is provoking a lot of interest. It's a tantalizing image. Great stuff.

Olly

[andyo]

great image

[pyrasanth]

Well this is the improved image & I'm really happy with it. Hope you all like it!

 

[gnomus]

Excellent.  It was definitely worth giving it that bit of extra work.  

[pyrasanth]

Thanks Gnomus- I'm really pleased with the result and the forum gave me a lot of clues. Ultimately the image is built on three layers & each was able to be processed separately because of that flexibility. The background stars were a real pig as they had to be hand finished as the noise in each RGB layer was simply awful. The HA layer which gives the image the fire took a lot of work & the RGB on layer 2 + the L was also loaded with noise. The whole project was not to be taken lightly. I noticed there are as few stars that could be tidier but you could go on processing forever so I think its time to stop & admire!

Thanks for all the helpful suggestions & I hope you enjoy the Lodestar X2 guide camera- all the M1 guiding was done with that camera so it has a legacy!

[gorann]

Congratulations.

that final one is clearly a great image and close to nails it!

I only say "close to" since I know that whenever I later look at one of my own, I cannot stop myself from trying to find a way to improve it......

[pyrasanth]

Thanks gorann- your encouragement is positively appreciated- that image was hard work but I've learnt a lot about post processing which will help me in the future. I'm glad you like the image.