North America Nebula 12-6-11

[Carole]

Did this in the early hours of this morning, got as much as I could before it disappeared behind the POD dome.
Hope to get a chance to add to it as it's noisy.  
Using my new Sky-Watcher Evostar-80ED DS-Pro (I'm selling the Megrez)
Modified Canon DSLR EOS 450D and CLS filter.
12 x 5mins 800 ISO + D,F, DF and B
Processed in DSS and PS CS3

Using the same flattener as the Megrez, I still have distorted corner stars but not quite as bad as the Megrez, so might have another try at getting a spacer.

N.B. Tried to put this on the gallery but it's not playing ball today.

[MarkS]

It's a good start but, as you say, a bit noisy.  The colours look good - especially the main 2 stars.

It looks like the black point has been set a bit low - if you set it less black I think it will look better.

Mark

[RobertM]

As Mark has said it's coming along nicely but it needs a lot more subs.  Altering the black point will cover up the noise to a degree but you could try some noise reduction on the dark areas instead.

I think the next thing to work on is star bloat, that bright star is a good example.  Did it start out that way or as a result of processing?  Dewed optics can cause that effect.

Robert

[Carole]

Thanks Mark and Robert.  Agree with what you say.  Believe it or not I did do some noise reduction, but I'm really struggling with star bloat.  Have been given a few ways of reducing star size but always seem to end up with a ring or halo despite feathering.  But will take another look at some of the options.  

I had dew heaters on so I don't think it was dew although I never actually looked into the lens to double check.  I am 99% confident that they were working OK.    

Perhaps you would be kind enough to give me a lesson at some point on how to reduce the bloating, using Photoshop.
Since this is hopefully not going to be the final image I won't go too far with re-processing at this stage.

Carole

[RobertM]

Sorry Carole I haven't used PS for astronomical images for a while now.  I do use it for normal pictures sometimes but they don't usually suffer from star bloat.

Robert

[Carole]

normal pictures sometimes but they don't usually suffer from star bloat.

I am sure I'll get the hang of it eventually.

Carole

[MarkS]

I'm not a PS user either.  Having said that, I did use it yesterday to perform a masked replacement of a star trail in one sub with the equivalent background from another sub.

Mark

[Carole]

Had a go at trying to reduce the bloated stars, I think this is slightly better, but as you can see I get a slight ring around the left star whichever way I try to do it.

[mickw]

Just guessing, but it looks like you are using whatever process too severely.
It looks as though the process is treating the nebulosity around the star as the star itself, tightening the nebulosity into the star.
Hope that makes sense.

[Carole]

Mick's re-process of his NA Nebula inspired me to have another go at mine.

I think I've got the stars better this time and Pelican shows up better as well. 



Carole

[mickw]

Like the way you've tamed that git of a star 

[Carole]

Like the way you've tamed that git of a star

I was sure I tackled the stars the same way last time, but maybe I didn't 'cos it's come out different.

On the basis of your thread and this one, I hope you are not going to take the first process as the one to present for "members images" Mick.   

Carole

[RobertM]

You'll have to process that star separately to tame it any more.  I'm sure I wrote the process down somewhere, I'll see if I can dig it out...

Robert

[MarkS]

The fainter nebulosity e.g. Pelican, has come out better but you've lost most of the colour in the 2 brightest stars.

[Carole]

you've lost most of the colour in the 2 brightest stars

Yes I noticed that.  

But how many re-processes can one thread take?

Carole