A quick stacking question

[Whippy]

Morning all, some of you may have seen my first baby steps into the world of imaging and I've been using registax to erm, stack the exposures but here's the thing. I'm not noticing a great deal of difference between one single exposure and the stacked versions.

Here's one shot from last night's M42:

(click to enlarge)

And here's the raw stack:

(click to enlarge)

To my uneducated eyes, there's not a whole heap of difference. All I'm doing in Registax is loading the shots in, selecting a alignment box and letting it do it's thing. Am I missing something?

Tony..

[Beyond_Vision]

You will need to stack at least ten frames to make a significant different to the signal to noise ratio. Also if there is only small amount of noise in the frames then the stacked image will not show any great difference. The kinds of thing you will notice with sufficient frames will be a better contrast with darker background and slightly more detail.

Regards

Kevin

[Grant]

How many exposures have you got Tony? If you want us to have a play, zip them up and add them as a file on the UK Astronomers site (new feature! ) then we can download them and have a go...

I'll have a play and report back the steps I take and see if that helps..

Cheers,

Grant

[Whippy]

You will need to stack at least ten frames to make a significant different to the signal to noise ratio. Also if there is only small amount of noise in the frames then the stacked image will not show any great difference. The kinds of thing you will notice with sufficient frames will be a better contrast with darker background and slightly more detail.

Regards

Kevin

Kevin, the stacked version has 50 subs in there!! And I wouldn't think for one minute that my Canon Powershot's sensor is by any means noise-less... I'm thinking there's surely a bit more than just aligning and stacking!

Grant, I'm just uploading the subs onto the site right now, enjoy!!!

Tony..

[SteveL]

send us a link when its ready

[Whippy]

Hm, It doesn't want to play ball. It's a fairly chunky zip at 110Mb but I've tried several times but no joy. Any ideas Grant??

Tony..

[Whippy]

Finally!!!

http://ukastronomers.com/user/add_files#whiplash/action/files/show/2/ajax/true

Tony..

[Grant]

Hi Tony,

Had a play and heres my attempt, not the best but I think I've brought out some more detail:

(click to enlarge)

I've also uploaded the raw stacked image, so anybody else can have a go at processing it without having to stack it again - it was stacked in deep sky stacker...

http://ukastronomers.com/whiplash/action/download_files/fileid/3

Just realised - I uploaded these files into your account on UK Astronomers Tony - hope thats ok!

[SteveL]

Some quite severe vignetting on the original jpgs

[Whippy]

Nice processing Steve, any pointers (or indeed a masterclass) on how you pulled it off?

I had to look up vignetting and see what it meant! Shows what I know doesn't it...I know what you mean and I haven't got a clue on how to get rid of it. Any ideas?

Tony..

[SteveL]

IMHO, use registax for planets/lunar images. For DSO stuff, use DeepSkyStacker. I have never had much (or any luck) with Registax for DSOs.

Stacking doesnt magically make your images brighter, all it does is make your final image "smoother", allowing it to be processed further before the noise starts to be a problem. If you look VERY closely at your two initial jpgs you posted, you can see the single frame is far more noisey than the stacked one.

With your subs, i think the order of events were something like:

levels

Gradient XTerminator

Noels Tools -> space noise reduction

curves

saturation

duplicate layer, set opacity to 50%

high pass (to taste) on the upper layer

crop, copy, paste, convert to 8 bit, save as jpeg

[Whippy]

Ta muchly mate for the pointers, I've DL'd DSS and I'm letting that do it's thing. I think I'll ask L'missus to get me a 'Photoshop for Idiots' book for Christmas. I've ignored learning how to use it for far too long.

Tony..