M51 (second attempt at DSO)

[Aza]

Hi

I added a CLS filter for last night's shots, and it made a massive difference.

I took about 60 x 2min shots, but only 21 were any good to stack.

So I am looking forward to taking more shots to add to the 21 I have.

Will adding another hours worth of data improve these by a large amount?

Also when I get into using RGB filters, can I use this data with the RGB?

My processing is not up to much, so would really like to see what can be achieved with my data. So if you have a few mins please go ahead and download the files and have a go.

http://www.megaupload.com/?d=21XG7KFS

Cheers

[zhgutas]

Lovely couple! and indeed, what a difference from the last time. You are certainly going the right way

marius

[**Space*Hopper**]

The CLS filter has indeed made a significant improvement on what were already very good images and these are even more impressive, well done :hello1: .

Looks like I might have to invest in a filter

With reference to the benefit of adding more data, from memory I think there was a post not so long back titled "what a difference an hour makes" on this very subject so you might want to try and track that down as I think it will help answer your question.

:wave:

Ian

[radioactive]

Wow! That's what I call progress for sure, I think you must be well chuffed, the filtering of bad light pollution has made a mile of difference!You are going to produce some knock-out images in the future going by this. As its only your second attempt I would hope that you can keep the saved data for future use also, but that needs explaining by someone who knows. That is not me. I know when you do your rgb filtering you can cut your expos time in half and use the x2 binning on it that's about all I can say we need a real imager to comment now

Well done Arran mate top marks for your effort thus far

[Beyond_Vision]

Great shot, I would be very chuffed to get a pic like that on a second attempt at a DSO.

Regards

Kevin

[Aza]

Thanks everyone, the CLS really did make a big difference

[Dave Moulton]

Arran,

A big jump in quality over your first post. A good amount of detail, such short subs as well.

I couldn't download your file, said it was not available. Anyway I downloaded your jpeg and just gave it a boost in Photoshop using curves while trying to preserve the core.

You may also want to try Deep Sky Stacker to stack your images a free program that does a superb job.

Well Done,

Dave Moulton

[algol]

very nice effort that is mate, it's been on my obs list for a while now, nice shot.

[RobH]

A big improvement Aza, nice one

Yes, adding another hours worth of data will certainly make a difference, you'll be able to push things more in the processing as your signal to noise ratio will have improved quite a bit.

You will certainly be able to use this as the luminance data for a LRGB image.

As Martyn says, you can bin your RGB data 2x2. This means you could either cut your exposure times in half, or go for the same times but with greaster sensitivity, the end result of which will be better and deeper colour information.

As your exposures are pretty short anyway, I'd advise doing this. Go for 15 or so 2x2 binned subs for each filter.

Cheers

Rob

[Aza]

Thanks Dave for giving it a go at processing. How can I get more detail in the core? Would this require longer exposure times? Or would that just increase its brightness?

Rob cheers for the info there. So how will a colour image look if I go binned or unbinned for an hour of each RGB channel? Over the same amount of time, will the better resoultion colour look better or the greater sensitivity version? Also when you say go for 15 binned subs, would it be better to go for much more? Say an hour on each channel to match an hour of luminence?

Thanks for the help

[Whippy]

Arran, I'm by no means an expert but here's how I understand it...

Our eyes pick out the detail in the Luminence, not the colour (although it gives the eyes more information to look at ) so you almost get the same level of detail by binning your colour exposures at 2x2 rather than the usual 1x1. Binning the camera makes it 4 times more sensitive (4 pixels become 1 'virutal' pixel) so lets say you have 1 hours' worth of L data, if you binned your colour data at 2x2 you can do 15 mins of Red, Green and Blue (although you may need to do more Blue because of your camera's chip insensitivity and the atmosphere scattering Blue light) and your pic should almost have the same level of detail as if you did your colours at 1x1. The main advantage is that instead of taking 4 hours (1 hour for L, R, G and , it's only taking 1 hour 45 mins to get the pretty much the same result.

MartinB's primer makes much more sense: http://stargazerslounge.com/index.php/topic,21557.0.html .

HTH

Tony..

[Aza]

Thanks for the explanation Tony, I shall have a good read of that link.

This forum is a very valuable resource indeed! Lots of great advice from members here.

Cheers

[RobH]

Hello Arran,

Tony's advice is bang on in general and well explained.

I would advise going for at least 15 exposures for each of your colour filters though, binned or not, in order to get a good signal to noise ratio in your colour image.

For luminance, go for as many sub exposures as you can, you can't ever have too many. This, as Tony says, is where the eye picks up the detail, and this is where you need the best S/N ratio as you'll want to bring out all the interesting faint stuff in processing.

Cheers

Rob

[Dave Moulton]

Thanks Dave for giving it a go at processing. How can I get more detail in the core? Would this require longer exposure times? Or would that just increase its brightness?

Thanks Dave for giving it a go at processing. How can I get more detail in the core? Would this require longer exposure times? Or would that just increase its brightness?

Cheers Arran,

Longer exposures to bring out core detail, probably not. I think it is more a question of preserving the core detail when you stretch the data.

In photoshop using curves you can brighten the image up, while placing an anchor point related to the galaxy core brightness before you move the curve. That way you don't overstretch the highlights. Other techniques exist that do a good job the history brush can recover lost detail. Digital development filters do a superb job as well.

Astro Processing video tutorial link

http://www.waid-observatory.com/article-curves.html

HTH

Dave

[Sam]

Arran,

That's a great result, you're leaping ahead very quickly!