Re-worked M27

[astro mick]

Hello everyone.

My last posting of M27 received a lot of reply,s about over processing.

I have tried to re-work this image to some degree,i have,nt used Noel,s Actions which i do quite a lot.

Using our new Format: Honest opinions welcome,with no back patting.

Let me know.

Mick.

[Psychobilly]

In general the processing is a lot more "natural" but it is crying out for flats to sort out the dust bunnies...

Failing that the sooner you can tackle the background irregularities in the post processing the better...

[Darth Takahashi]

Its a lot better, much more natural.

I hope you don't mind but I have fixed the issue with the background for you, Matt (Squid) knows how to do this and you can discuss it in detail with him.

1. Essentially I have copied the original image.

2. Used Dust & Scratches to remove most of the stars

3. Taken out M27 with the clone tool

4. Applied a final Gaussian blur

5. Applied the layer as a difference with the opacity set at approx 50%

Sorry if this is all complete nonsense to you but again Matt (Squid) can demonstrate this technique to you.

This is a rather nice way to create false flats but nothing beats the real thing - flats should be made at approx 1/3 of the full well depth of your CCD camera what ever that is? Take them before or directly after imaging because if you disturb the dust motes before taking them, they will not work.

[shaunster]

Much better, more natural look and it doesnt have that 'processed' look. I'd say if you had flats then you would be able to make this a much smoother image

[astro mick]

Hi Guys.

Thanks for taking a look,and yes i can see the problem,i was trying to dumb down the over processing,but of course having no where near enough darks,and no Flats at all,it does fall short.

In the recent discussions,i think calibration is something i should no longer ignore,so this is where i will start,when the clouds eventually clear.

Neil,dont mind at all,and it does look a lot better,and better still i think i understand what you did.

I must master flats though,and hopefully that will sort out the background.

Cheers.

Mick.

[roundycat]

I did a very crude high pass on the nebula and it does sharpen it up a bit. Cannot emphasise enough the need to get proper calibration frames. They knock out all the muck before you start stretching it.

Dennis

[ollypenrice]

Better but flats are essential.

I think the way you have stretched has made the problem worse.

Since the flats issue is embedded in the present data you could try, at least, not to stretch it into visibility. Instead of doing stretches by lifting the curve from the very bottom, put a pin on the curve at the background sky level in an early stretch before the bunnies are shouting. (Cursor on the background sky, then Alt plus CLick.) A 'pin' appears on the curve. Now drag that pin on the curve upwards just a tiny bit and leave it there. Click on the curve above the pin and stretch from there. With a bit of luck you will stretch the nebula but not the bunnies.

Olly

[astro mick]

Ok Olly.

I understand that.

Cheeers.

Mick.

[Darth Takahashi]

I never used flats and for a long time I ignored them and all those people who go on and on and on about them!!!

Why, because I have and ST10 with a small chip and a telescope that can illuminate 90% of a medium format frame (6x6cm)... I thought flats were for vignetting only?

This is a mistake, here are the two reasons why everyone should make flats;

1. Shocking news - the sensitivity of the pixels of your ccd camera is not perfect, that is they do not all respond perfectly to the same photon flux. the difference is minor but it is there and once you start stretching the image you actually amplify the difference. So it normalizes the sensitivity of your ccd camera.

2. It conveniently removes all the dust motes and other minor imperfections and anything you can do to simplify your post capture image processing flow has got to be a good thing. You don't want to remove these by hand with the clone tool later.

That's other than to say don't go buying any expensive equipment to make flats, I just throw a white cloth over the telescope and take them at twilight. The biggest mistake people make is to forget about just how much amplification their telescope gives, light levels need to be low to take flats otherwise you will just over-saturate them and then they are of no use.

[ollypenrice]

It must be me but I can't get sky or T shirt flats to work. I always get gradients with them so I have forked out for a panel. But if they work for you, don't waste money!

Olly

[mark7331]

It must be me but I can't get sky or T shirt flats to work. I always get gradients with them so I have forked out for a panel. But if they work for you, don't waste money!

Olly

I can never get sky flats to work but our best cotton pillow covers work a treat.

Looks a bit silly on the scope though...

Mark