M27 Dumbbell Nebula Ist narrowband Image

[Carole]

Following on from my previous post on this, I have now spent several hours on this experimenting with the stacking to get rid of the Hot pixels prominent in the previous posting.  I had to alter the settings in DSS in cosmetic to get it just right and so I didn't end up with holes in the stars and also used Kappa Sigma stacking.  Spent the best part of two days on this!!!!!!!!!

Anyway, this is a combination of Ha & Oiii only - I took Sii but didn't like the resulting colour.  Things still to put right (I was using a wider band Ha filter - which I had bought for using on the DSLR which has resulted in red rings around the stars, so looks like I will have to fork out more dosh and buy yet another Ha filter).  N.B. I have managed to process out the red rings in the brighter stars.

So -
6 x 1200 secs Ha 12nm Astronomik
9 x 1200 secs Oiii 8nm Baader
Atik 383L + Cooled to minus 10 degrees
Skywatcher Evostar ED80 pro
Guided with QHY5 on NEQ6

[Carole]

Although I don't like some Hubble images I decided to have a bash at it - if you can't beat them join them:

Ha = green 12nm Astronomik
S11 = Red 8nm Baader
Oiii = Blue 8nm Baader

don't know what the hell I am doing so any advice appreciated.



Thanks
Carole

[MarkS]

Seems like there's lots of stuff to learn about narrowband imaging

That second image is looking good though the Dumbbell is fairly small in that field of view.

If you get red rings in the stars in the first image, why don't you get green rings in the second image?

Mark

[Carole]

If you get red rings in the stars in the first image, why don't you get green rings in the second image?

That thought crossed my mind too Mark, though I have done so many versions of this processing I can;t quite remember now whether there were green stars and perhaps I toned them down.

Yes the Dumbbell is a small target for the FOV but I decided to start off with something simple, and I had not yet got the flattener spacing sorted so needed to crop off the far corners because of coma (is that the right word).  I've now received some spacers so will be trying these out for the next image.

Thanks
Carole

[Ivor]

Not bad first attempt, on the first image how did you assign the channels? I'm still very much learning myself but on the M20 image I did the other day I played around with the mixture in the the blue channel until the stars came out right, it might be something to try.

I think your first attempt at the Hubble palette is pretty good, however I'd suggest considering a different target with more varied detail so you practice. I'm currently working on NGC7635 - Bubble nebula, it has more nebulosity and when framed with M52 it gives a mixture of challenges.

Maybe start up a thread with our lessons learnt so we can learn off each other?

[Carole]

Thanks Ivor. 

This was just a learning image, so I chose something fairly simple. 

on the first image how did you assign the channels?

Ha = Red
Oiii -= Green

Maybe start up a thread with our lessons learnt so we can learn off each other?

That might be a good idea.

I have since been told that the bandwidth doesn't make any difference to the star size (though from what I have seen I am not so sure), it just makes a difference to how much "muck" is excluded from the sub.

Does any-one have any ideas how I can stop those red stars? 
Also had to be quite aggressive with Stacking to get rid of the hot pixels.  So maybe I'll start up the thread with these items.

Carole

Carole

[Ivor]

For the first image create a blue channel using the HA and Oiii merge the layers with 40/60 ratio. That should help the balance, I've found the HA can really take over the colour balance, as I've been aligning the channels PS I've been using the Minimum filter to remove the colour fringes on the stars.

I need to find a better solution for channel alignment as I have some plate rotation in another image which is preventing me processing it any further. How are you aligning the channels?

[Carole]

I'm using Channels. 

How are you aligning the channels?

I align the individual images in Maxim (it's the only thing in Maxim I have worked out how to use), then I make a duplicate of one the images.  Make sure they are all greyscale except the combi duplicate which is RGB.  I then copy and paste the various filters into the relevant channels.

There is another method which Mac describes (see the stickies, more than one way to skin a cat), but that doesn't seem to work for me, I have seen another similar tutorial on Starizona which is similar but with some differences, which I plan to try when I get some time. 

Just tried your suggestion Ivor, it's amazing how differently different combinations of filters can come out. 

Carole