Iris Nebula - woe is me!

[Tommohawk]

Latest is we've been living in Somerset for the last 2 years, but as of last week back to East Sussex. Long story, all good.... until 2 days back when I discover that in our absence one of the neighbours has fitted a floodlight in the garden - no PIR sensor, just on all the time - and uplighters in the pond.

Anyhow I've posted my result even though it has multiple faults which are:

1. Massive burnout to the left (bottom) due to massive light pollution in out otherwise excellent skies.

2. Coma because even though I used a CC I used the wrong spacer. (Jet lagged possibly, Somerset is about 15 mins different)

3. Eccentric coma because I put the camera on in the dark it it wasn't quite square to the focuser tube. Also I dropped the scope in the move and the focused was screwed tight double quick and wasnt square to the scope. That's now been sorted.

Processing a bit hasty but really wasnt worth any effort with the LP. I'm going to have a word with the neighbour but don't hold out any great hope. Trouble is although the skies here are generally very good, my views are very restricted due to high banks and trees to the East and also trees to the south, and out own house of course. Mostly I'm OK to the north - apart from the new LP which is also north. Hence the "woe is me."

Ive been thinking about NB for some time, and this latest LP disaster may push me into it, though I'm loathe to splash out a heap more on filters when my views are so restricted. Any thoughts on just how effective NB is for combatting LP?

Here's the result. Best 75% of 50xL, 29 x each RGB, ASI1600MM at -10degC and unity gain, flats (from previous session with high gain so mis-matched) no darks. DSS and PS.

Probably would have cropped it but left full frame to demo all the nasty coma and LP. Thanks for looking - happy to hear thoughts/criticisms, but mostly just after sympathy.

 

[Rodd]

That actually looks pretty good...drop the black point and I think the nebula will pop.  I think the gradients can be handled with DBE (or gradient exterminator).  You might not get allot of the surrounding structures, but the Iris itself I think will be very nice.  

Rodd

[AKB]

Looks better than mine, and I don’t have the LP.  You didn’t say how long the subs were?

[carastro]

I sympathise with you and wish you luck with the neighbours, there is no need to have the light on all the time.  

I had a fiddle with your image and if we disregard the coma which you are aware of, after a bit of gradient exterminator and a couple of curves + Noise reduction despeckle, it looks rather nice.  Probably stretched the stars a bit too much, but just a quick demo.   Hope you don't mind me posting.  

I know the skies of East Sussex of course depending where you live as we often go down to a campsite near Burwash, and it's very dark there.  

As regards NB filters, well I think they will combat a certain amount of LP, but from where I live (suburbs of London) only the brightest targets are doable.  But they are better than broadband.  

Carole 

 

[Macavity]

No "Classical Imager" Me! But sometimes I just can't resist. lol 
With IRIS's Polynomial Gradient Removal  + a few "Levels" cuts:
And just GIMP on .jpg... Maybe with a bit more sophistication?

Maybe I'm more used to light pollution and other "rubbish"...  

[Tommohawk]

1 hour ago, Rodd said:

That actually looks pretty good...drop the black point and I think the nebula will pop.  I think the gradients can be handled with DBE (or gradient exterminator).  You might not get allot of the surrounding structures, but the Iris itself I think will be very nice.  

Rodd

Thanks Rodd - and looks like other folk have done just that for me!

1 hour ago, carastro said:

I sympathise with you and wish you luck with the neighbours, there is no need to have the light on all the time.  

I had a fiddle with your image and if we disregard the coma which you are aware of, after a bit of gradient exterminator and a couple of curves + Noise reduction despeckle, it looks rather nice.  Probably stretched the stars a bit too much, but just a quick demo.   Hope you don't mind me posting.  

I know the skies of East Sussex of course depending where you live as we often go down to a campsite near Burwash, and it's very dark there.  

As regards LP filters, well I think they will combat a certain amount of LP, but from where I live (suburbs of London) only the brightest targets are doable.  But they are better than broadband.  

Carole

Hey Carole thanks for that! Looks very nice especially given you only had the PNG. We're about 10 miles south of Tunbridge Wells and skies here are remarkably good - as you say Burwash is also good and a nice village too. I'll post back when I've had the neighbour discussion - I think the best I can hope for is maybe they'll turn the lights off for me on request when I'm imaging, but the idea of having to plead with them to not pollute the sky grates a bit.

1 hour ago, Macavity said:

No "Classical Imager" Me! But sometimes I just can't resist. lol 
With IRIS's Polynomial Gradient Removal  + a few "Levels" cuts:
And just GIMP on .jpg... Maybe with a bit more sophistication?

Maybe I'm more used to light pollution and other "rubbish"...  

 

Hi and thanks also for that - I think I'll just give up on processing and post all the raw data here!

[Tommohawk]

15 hours ago, AKB said:

Looks better than mine, and I don’t have the LP.  You didn’t say how long the subs were?

Sorry, I left that info out. All 60s subs. Funny thing is that the star count in DSS is very low and I had considered longer exposures, but not sure if that would work with LP. 

[Macavity]

15 hours ago, Tommohawk said:

Hi and thanks also for that - I think I'll just give up on processing and post all the raw data here!

I can relate! lol. To this day, I have never been able to reproduce what
another SGL'er extracted from one example of my early image data!

But (as noted above) a Gradient Reducer (IRIS & Gradient Xterminator
put up the same dialog box?) might just remove a LOT of the crud in a
single click! I've never become particularly involved in (LRGB) Narrow
Band Imaging, but I find a combination UHC (H-Alpha plus O-III) filter 
-- like the "Baader UHC" etc. work wonders for One Shot imaging... 

[Tommohawk]

I've never had need of gradient correction before so this is all new. I looked at Gradient Exterminator and looks like $50 - that an awful lot for one plug-in. So I'm playing with Doug Germans method which looks to hold promise. One slight problem though but hopefully I can sort that and then I'll post back.

[carastro]

It does seem expensive, I think that is £39 English money, but I have used it a lot over the years and to do without it would be extremely difficult.  Single licence but you can install it on more than one laptop/PC.  

Carole 

[Tommohawk]

Yes probably a good investment, but I like to try and avoid automated fixes - not a purist, just stubborn.... or maybe mean..... or probably both!

Anyhow I followed through Doug German's tutorial on gradient fixing and it was useful - learned a bit more about applying images in PS. He suggests doing gradient fix at the outset before processing but that means you have to do it on the RGB and the L image before layers which is a heck of a faff! Maybe I'll just do it at the end next time and see what happens. I think I have now have the spacer sorted for the CC also. Anyhow here's my best shot:

 

 

[carastro]

That's come out really well.  I know what you mean about automatic fixes, I don't tend to use actions for that reason as I am simply using other people's skills and I am not learning anything, but sometimes I have to give in if I can;t find another way.  I will take a look at that "Doug German's tutorial on gradient fixing".

Carole 

[DaveS]

In AstroArt, after stacking (With the option to add "fake" borders to cover alignment errors ticked) I run at least one iteration of gradient removal before RGB or LRGB synthesis, since AA5 has some pretty good tools for gradient removal, and with my variable LP I often find differing gradients on each stack. Usually it'll be Remove Gradient > Adaptive Divide, though I might run a Remove Gradient > Linear first if there's a severe linear gradient. After doing the synthesis I'll run a Remove Gradient > Adaptive Subtract after getting rid of any dodgy alignment edges, which can throw the removal out.

After that, when doing the stretching I'm not trying to stretch / process the gradients.

[Tommohawk]

Thanks for that Dave. Not familiar with AA at all but sounds good. I also ran into problems with my gradient removal because of misaligned RGB edges - the blur action applied to the frame to be subtracted ends up with darker edges - cropping first seemed to fix it.

Made me wonder if its possible to create a flat from the lights using this method, ie make a blurred version of the lights and apply this during processing in DSS? This could take account of gradients and vignetting, but wouldn't fix bunnies of course because they would be too blurred. Also if the main feature is a big bright thing, as it is with The Iris, the centre would be incorrectly darkened, so maybe not! 

 

[CCD Imager]

Tom

Sorry to hear of your woes, but next time you will have it all corrected? I have a similar problem with next doors outside light, on at sunset off at dusk, but not directly in line with the telescope. I had a similar problem many years ago and built a 8' x 8' screen that I erected each time I imaged. Could you do something similar, or buy them a beer and discuss light pollution?

[Tommohawk]

5 minutes ago, CCD Imager said:

Tom

Sorry to hear of your woes, but next time you will have it all corrected? I have a similar problem with next doors outside light, on at sunset off at dusk, but not directly in line with the telescope. I had a similar problem many years ago and built a 8' x 8' screen that I erected each time I imaged. Could you do something similar, or buy them a beer and discuss light pollution?

I'll try discussing it first - especially if it involves a beer! I had another look last night just as it was getting dark and I think there may be 2 separate problems - one neighbour with pond lights and the other with floodlights. I could try a screen, but the light seems to spread and bounce back from the trees at he end of their garden.

One solution would be a nice row of Leylandii about 5 metres tall. This would block a big chunk of sky, so not ideal, and it would also block their sunlight given I'm to their south. I'm thinking that the threat of this might encourage them to see the error of their ways!

Perhaps the discussion with refreshments first though!