NGC 1300, LRGB reprocess attempt

[rogerg]

Hi all,

I'm attempting to get to the bottom of LRGB issues I have. To this end I have spent most of today trialing CCDStack to see if it and I get along. This image is processed in CCDStack with a few tweaks in Photoshop later.

I think CCDStack has made the job more successful than manual processing in CCDSoft + Photoshop, and it has been easier to learn than PixInsight which does my head in (and isn't fully supported on my 32bit OS). Tempting to buy CCDStack, but am searching for LRGB data to get more of a feel.

This image has more contrast of colour than I normally get in my galaxy LRGB images, in that there's a more yellow core, bluer arms and some magenta knots in the arms (depending on which screen I look at it on!). It's more normal I end up with a washed out yellow awful looking thing.

CC much appreciated.

12" SCT @ ~f/10
ST8-XME @ bin 2x2
L=20x300s
RGB=20x180s each

Data captured in December 2012.

Regards,
Roger.

[rogerg]

Another attempt after checking it on my calibrated screen.

[PRejto]

Hi Roger,

I think you have done well with a tough candidate! Perhaps you might pick a target next that has a lot of colour, isn't so small, and is brighter! That might give you a better feel for CCDStack when you are not fighting so many difficulties. I'm a big fan of CCDStack. It made a huge difference to me when someone kindly suggested I give it a try. In case it wasn't already mentioned, the tutorials of Adam Block - one each for CCDStack and Photoshop - are outstanding. If you have any questions about CCDStack I can try to help you with what I do know.

Peter

[rogerg]

Thanks Peter :) I guess you could be right, I'm not choosing the most colour diverse targets! I tend to avoid nebulas because my camera is NABG but with deblooming in CCDStack perhaps that might change.

Good to hear you found CCDStack so good. Do you use many if the different registering algorithms, or data processing algorithms? In my limited time today I've found I've just stuck to the basic settings and wonder if I would get much from the other features.

[Ross G]

Nice capture Roger.

Good luck with CCDStack.

Ross.

[strongmanmike]

So you sit on data for 10 months Roger?..good idea save for a rainy software testing day :D

Those arms are quite long huh?

I have this on my list of possible targets for Oct/Nov :thumbsup:

Mike

[PRejto]

Hi Roger,

Well, the basics work pretty darn well so I've not ventured too far away. I sometimes use quadratic b spline but actually find the most dramatic effect is the data rejection one does just before the final stack combine. Getting that just right takes a bit of experimentation. I usually look for about 1.5-2% reject/frame but the frame you have registered will show a far greater reject. I was told that this is because it is the only frame that is not reprocessed and not to fret over it. Sometimes it seems a shame becuse it is usually the best frame one started out with. The forum at CCDWare is quite responsive so you can ask questions there even if you are still in trial mode. A I have CCDInspector installed in the initial alignment I have only used the very first tab for aligning the images. It has always worked quite well and will even align images of varying image scale. Of course it combines 2x2 and 1x1 but also woked for me combining images that varied by several 10ths in resolution (I was experimenting with a barlow and had a variety of images that were slightly different image scale and rotation. It didn't have any trouble at all dealing with these).

Peter

[Lee]

Nice one Roger.... What does the luminance frame look like??

[Shiraz]

well that description certainly does not apply here - nice image.

[gregbradley]

Nice galaxy image there Roger. Great image scale.

I use CCDstack and usually apart from the fact it is tediously slow with large files its quite good.

As far as rejection goes I only use hot/cold pixel rejection. Perhaps that may vary with different model cameras but my FLI cameras are so clean I find that is all that is needed. It gets rid of those little coloured dots in the background that seem to sneak in somehow in filtered imaging.
Not sure what the other rejections do. I have tried them several times and can't see any difference. Or they select way too much of the image and damage it.

CCDIS is a good addon to CCDstack as it usually gives an excellent registration.

CCDstack has been evolved gradually over the years. Apart from the CCDIS I don't think its really improved it at least for my use. In fact its a little more awkward now than the earlier versions "more sophisticated" = (more clicks to achieve the same end and more automatic stuff that fights you for control).

Greg.

[rogerg]

Two new pics attached....



Thanks :) Do I need it? :)



Yeah, have to admit there's often data that sits around a while Mike :) Capturing data is no issue with PME + automation, processing it takes much more effort! And when it comes to LRGB and my poor results generally, I often give up pretty quick. In this case I don't think I previously published the Luminance data on its own either! Very bad of me :)



Interesting. I didn't realise CCD Inspector hooked in for image registration, I wonder how that works... the image registration in CCD Stack seems to work fine? Reading through the list of features I see there's a reasonable bit in CCD Inspector to do with image quality and registration. Seems maybe the line between these two pieces of software is less clear than I thought (I thought one was for stacking, the other analysing your optical setup).



Attached is the Luminance .... you prompting me to look at this made me see how much I was missing in the LRGB! Hence I've attached an LRGB with the curves stretched more.



Thanks, yes, a nice change. :)



Thanks or your input, much appreciated.

The one thing I fear I will miss out on with CCDStack if I go with it instead of the more complex PixInsight, is the DBE which I found useful for flattening the background of images. I wonder if there's an alternative in CCDStack?

[Lee]

It might be just me, but I like the luminance better - looks great.... :)

[rogerg]

Agree.

Perhaps I just need a whole lot more RGB data to get a nice RGB result.

[PRejto]

Yes. Process- flatten background.

I've found that it is frequently better to use this tool on the R,G & B frames before doing a colour combine. Also, (and it just might be my filters or camera, or light pollution filter) though the instructions say not to normalise the background when stacking the RGB prior to colour combining, I sometimes get better results if I do.

Peter