Sadr Region Ha

[Allinthehead]

Hi Everyone, as we're all dealing with very short nights it's very difficult to get any good data, and with the moon the last few nights i wondered if i was wasting my time. Quite happy in the end and i feel it was worth the effort. I got a 1mm spacer made but i'm still not happy with the corners.

How i wish sgpro would allow unguided dithering like APT does, as i have some walking noise. I'm taking a chance these nights leaving the kit out all night with intermittent cloud about. Does anyone have any recommendations for a rain sensor? 

Anyway this is 6 hrs in 30 second subs at gain 399 offset 50 with the Asi 1600mm

Lens is the Samyang 135

Astrodon 5 nm ha filter

Stacked in dss and processed in PS. Levels, curves, Noel Carboni's local contrast, star reduction. Selective sharpening, noise reduction on background.

Hope you enjoy,

Richard.

Just realised i stacked without flats. Interesting comparison.

 

 

 

[Uranium235]

Looks great so far!

Re: your corner problems. Is it all four corners or just two? Or is it a combination of 2 with coma distortion, and the other two with rotational distortion.

If its two, or a combination of distortion it might well be that the lens is not secured tightly enough. At f2, even the smallest of mechanical inaccuracy will give you problems.

[Allinthehead]

 

4 minutes ago, Uranium235 said:

Looks great so far!

Re: your corner problems. Is it all four corners or just two? Or is it a combination of 2 with coma distortion, and the other two with rotational distortion.

If its two, or a combination of distortion it might well be that the lens is not secured tightly enough. At f2, even the smallest of mechanical inaccuracy will give you problems.

Thanks Rob. In the image above stars look ok top right and bottom right. Top and bottom left however are distorted.

[rwilkey]

Hi Richard, I love the Sadr region but so difficult to see visually, the whole area is amazing.  Thanks for sharing.

[Rudeviewer]

30 seconds!!  Amazing where cameras have come from and what they can do now....Great Shot!

[Allinthehead]

2 hours ago, rwilkey said:

Hi Richard, I love the Sadr region but so difficult to see visually, the whole area is amazing.  Thanks for sharing.

Hi Robin. Thanks. I'm glad you like it.

 

55 minutes ago, Rudeviewer said:

30 seconds!!  Amazing where cameras have come from and what they can do now....Great Shot!

Thanks Rudeviewer. I think this will be the last narrowband image i do with exposures this short as the amount of data needed is ridiculous, not to mention how long it takes to stack nearly 800 frames at 31mb per frame.

[Uranium235]

4 hours ago, Allinthehead said:

 

Thanks Rob. In the image above stars look ok top right and bottom right. Top and bottom left however are distorted.

Next time out, if your software supports it - zoom into one of the affected corners with an ROI (just downloading part of the frame) and set it to a 1-3 second loop. Next, tweak the focus very gently... if the distortion worsens, go the other way until theyre round. Next go back to what was one the good corners to check they are still ok. Lastly, check all four corners to see if further adjustment is required. Takes a while yes, but its worth the effort.

[PatrickGilliland]

Super work Richard.  All the more considering the short nights and patchy weather, well done

[Allinthehead]

16 minutes ago, PatrickGilliland said:

Super work Richard.  All the more considering the short nights and patchy weather, well done

Thanks Paddy. Really looking forward to longer nights

[Barry-Wilson]

Well done Richard - fabulous widefield.  I really like it and the contrast across the frame is about right for my tastes.

SGP does do unguided dithering - I use it with my 10Micron mount.  You select the unguided option in the Guided tab and the normal dithering scale that you want (small, medium, large).

[Allinthehead]

2 minutes ago, Barry-Wilson said:

Well done Richard - fabulous widefield.  I really like it and the contrast across the frame is about right for my tastes.

SGP does do unguided dithering - I use it with my 10Micron mount.  You select the unguided option in the Guided tab and the normal dithering scale that you want (small, medium, large).

Barry you absolute legend. Just had a look at Sgpro and there it is. That's going to make a huge difference thanks for that.

[Allinthehead]

2 hours ago, Uranium235 said:

Next time out, if your software supports it - zoom into one of the affected corners with an ROI (just downloading part of the frame) and set it to a 1-3 second loop. Next, tweak the focus very gently... if the distortion worsens, go the other way until theyre round. Next go back to what was one the good corners to check they are still ok. Lastly, check all four corners to see if further adjustment is required. Takes a while yes, but its worth the effort.

I have another .5mm spacer to try. Hopefully between what you have advised and the spacer i can get reasonable stars. Thanks for the advice.

[Allinthehead]

This one is just for fun. Some extreme star reduction.

 

[ollypenrice]

Great result, but watch your black point. Don't bring it in too far. If you use Noel's 'Enhance Local Contrast' you need a long flat strip to the left of the histo peak because he'll eat into it. One workaround is to run the action as a top layer and set the blend mode to lighten.

Olly

[Allinthehead]

1 hour ago, ollypenrice said:

Great result, but watch your black point. Don't bring it in too far. If you use Noel's 'Enhance Local Contrast' you need a long flat strip to the left of the histo peak because he'll eat into it. One workaround is to run the action as a top layer and set the blend mode to lighten.

Olly

Thanks for the tip and your bang on, it was caused by local contrast enhancement. It's funny you should say that as i was thinking after processing it that i should leave more space on the left, and bring it in at the end. Plan is to add another couple of hours ha and then gather the OIII for a final bicolor.

[ollypenrice]

1 hour ago, Allinthehead said:

 It's funny you should say that as i was thinking after processing it that i should leave more space on the left, and bring it in at the end. 

Yes, the golden rule of processing. A final nudge to the black point should always be the last thing you do in the workflow. At any point before that you can easily preview the final result by giving the black point a nudge, but never apply it. You are very likely to need that space on the left and when it's gone it's gone.

Olly

[Allinthehead]

On 7/8/2017 at 10:50, ollypenrice said:

Yes, the golden rule of processing. A final nudge to the black point should always be the last thing you do in the workflow. At any point before that you can easily preview the final result by giving the black point a nudge, but never apply it. You are very likely to need that space on the left and when it's gone it's gone.

Olly

That's great thanks makes sense.

[Uranium235]

On 08/07/2017 at 08:23, ollypenrice said:

Great result, but watch your black point. Don't bring it in too far. If you use Noel's 'Enhance Local Contrast' you need a long flat strip to the left of the histo peak because he'll eat into it. One workaround is to run the action as a top layer and set the blend mode to lighten.

Olly

Exactly what I do, except I paste another one on top of that and set it to darken so I can have some control over how much gets applied.

Another trick is to make a copy, run local contrast on that - then copy everything except the stars and paste as a layer over the original (adjust opacity as required). That way the stars arent brightened by the action.

[ollypenrice]

42 minutes ago, Uranium235 said:

Exactly what I do, except I paste another one on top of that and set it to darken so I can have some control over how much gets applied.

Another trick is to make a copy, run local contrast on that - then copy everything except the stars and paste as a layer over the original (adjust opacity as required). That way the stars arent brightened by the action.

Excellent!!! Nice thinking, Rob.

Olly

[Allinthehead]

1 hour ago, Uranium235 said:

Exactly what I do, except I paste another one on top of that and set it to darken so I can have some control over how much gets applied.

Another trick is to make a copy, run local contrast on that - then copy everything except the stars and paste as a layer over the original (adjust opacity as required). That way the stars arent brightened by the action.

This is all great feedback. Learning with every image. To paste without stars would you select the stars then select inverse, copy that, then paste on original image?

[Uranium235]

36 minutes ago, Allinthehead said:

This is all great feedback. Learning with every image. To paste without stars would you select the stars then select inverse, copy that, then paste on original image?

Yea, if you use noels "select brighter stars" on the LC version, then do the following: expand=1, expand=1, inverse selection, copy, paste (on top of original image). That ensures you are clear of any stars and also prevents copying across any dark halos that are sometimes produced by the contrast action. Try the method of both lighten and darken layers, and if need be - experiment with layer masks so you can "brush in" highlights and dark bits where you see fit.

Sometimes you need no contrast enhancement at all on some of the bigger, thicker dust clouds - so making them even darker (almost black) doesnt quite look right - hence why its useful to apply contrast selectively via layer masks. As you would with sharpening... because you wouldnt sharpen something you didnt need to (as it may end up adding noise).

[Allinthehead]

Excellent thanks Rob. I'll work on this for the bicolor.