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M33 - Astronomik Clip Filter cyan tint removal?

PhotoGav

By PhotoGav
in Imaging - Deep Sky

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PhotoGav

PhotoGav

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Here is my recent attempt at M33:

post-29321-0-59522500-1386031074_thumb.p

13 x 600s subs, 15 x 600s darks, flats & bias.

So, I'm quite happy with it, but I have struggled with colour throughout the process. I used an Astronomik CLS clip filter on my 60D (unmodded) and the subs are quite cyan tinged. I have tried to correct this in photoshop CS3, but not really very effectively. The colours are quite washed out as a result as when I try and boost the colours, the cyany colour just jumps straight out, drowing any reds or yellows. I also see quite violent cyan/green halos around the stars, which I have failed to calm down in processing.

Does anyone out there have any crafty techniques for dealing with the colour cast of the CLS filter and the halos? If so, I plead with you to share your secrets with me!

All other comments / criticisms / suggestions / thoughts will also be gratefully received.

Thanks for looking.

Gav.

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lensman57

lensman57

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Here is my recent attempt at M33:

attachicon.gifM33-Final.png

13 x 600s subs, 15 x 600s darks, flats & bias.

So, I'm quite happy with it, but I have struggled with colour throughout the process. I used an Astronomik CLS clip filter on my 60D (unmodded) and the subs are quite cyan tinged. I have tried to correct this in photoshop CS3, but not really very effectively. The colours are quite washed out as a result as when I try and boost the colours, the cyany colour just jumps straight out, drowing any reds or yellows. I also see quite violent cyan/green halos around the stars, which I have failed to calm down in processing.

Does anyone out there have any crafty techniques for dealing with the colour cast of the CLS filter and the halos? If so, I plead with you to share your secrets with me!

All other comments / criticisms / suggestions / thoughts will also be gratefully received.

Thanks for looking.

Gav.

Hi Gav,

Here is a quick play in CS using the Noel's actions to remove the colour gradient and then playing about with selective colour a bit. It took about 30s all together.

A.G

post-28808-0-01353300-1386034150.png

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PhotoGav

PhotoGav

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Russe & A.G, thank you so much for your feedback. Spectacular changes & info from both! I will have a second attempt at processing this evening. It certainly looks as though the data is in there (along with vast amounts of dslr noise!), hopefully I will be able to tease it out more convincingly.

Russe, that's a great tutorial you've made with your M74 data. I'm trying to digest it all!

Thanks folks and, dare I say it, the forecast is looking good for tomorrow night!

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Nathan_Pembs

Nathan_Pembs

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I had a quick go at processing this, but I think more subs would help :)
Having tried M33 myself I found it's quite a wishy-washy target anyway, as it has a low surface brightness.

Also using an unmodded camera, you wouldn't pick out the active pink hydrogen areas.

post-15858-0-02061600-1386069694_thumb.p

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PhotoGav

PhotoGav

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Thank you Nathan, it seems that there is no limit to the number of subs required! As for the camera.... Atik springs to mind... Dear Santa, ........!

I wanted to extend on it, but no one seemed interested. If I find time, I could do some more screenshots.

I'm going to be working through what you have put up so far in some detail this evening, so expect questions!!!! As for the continuation and lack of interest - I have my hand up at the back of the class!

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davew

davew

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There is a body of opinion that would suggest the centre bulge of Galaxies, having a great mix of stars and colours, would make a reasonable place to find the white point of your image if you can't find a G2V star.

Dave.

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jgs001

jgs001

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Gav, do you use DSS to stack the images ? If so, let DSS create a custom white balance, that will sort out the CLS cyan tint...

In the RAW/FITS settings

Picture1.png

In the stacking parameters, set the RGB channels background callibration

Picture2.png

This is how I use the CLS and DSS together, and this deals with the cyan tint nicely.

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PhotoGav

PhotoGav

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Thank you John.

There's good news & bad news:

The bad news - I don't use DSS, I use Nebulosity.

The good news - There is something pretty similar that I have discovered in Nebulosity, Image / Auto Colour Balance... One click and CLS Cyan is history... Hoorah!

Here's my rework, it's far from finished, but the cyan glow has gone:

post-29321-0-45790400-1386089798_thumb.p

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lensman57

lensman57

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Yeah getting an Atik for me was a real game changer, it's quite an "old" one with a small chip but the benefits over a DSLR are great :)

I really like my very old and very well used 16IC mono , 314 L+ mono and the 428EX osc. Just don't have the courage to ask my wife's permission for a 460EX mono, I don't think that I could afford a new kitcen yet.

Regards,

A.G

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PhotoGav

PhotoGav

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Ah, interesting... An osc CCD - is that significantly better than a dslr? I had the impression that a CCD 'should' be mono to get the best out of it? Then I worry about the time to capture the data for all four channels and that I have to set up each time, so 'just grabbing another couple of hours of data' is a fairly lengthy process, making the completion of a picture a major effort... So, osc could be the next step?

Indeed, the justification process can be problematic. It does provide a balance to the other half's 'essential' handbag/shoes/haircut/clothes purchases though!!!!

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lensman57

lensman57

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Ah, interesting... An osc CCD - is that significantly better than a dslr? I had the impression that a CCD 'should' be mono to get the best out of it? Then I worry about the time to capture the data for all four channels and that I have to set up each time, so 'just grabbing another couple of hours of data' is a fairly lengthy process, making the completion of a picture a major effort... So, osc could be the next step?

Indeed, the justification process can be problematic. It does provide a balance to the other half's 'essential' handbag/shoes/haircut/clothes purchases though!!!!

A mono CCD  is much more sensitive than an OSC but unless you are lucky enough to enjoy true dark skies then RGB imaging is really at the mercy of your sky. With NB there is no contest mono rules. I also feel that at times, given the fickle nature of our skies a sensitive OSC camera maybe of more use to a rank amateur in terms of time invested in imaging and the final result, although a mono CCD and an Ha filter can produce beautiful images of nebulea rich in Ha.

A.G

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PhotoGav

PhotoGav

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AG, do you have a gallery of images shot with your CCDs? I'd be very interested to see what kind of results you are acheiving.

It's a dangerous hobby this... The temptation is to throw endless piles of cash at it, but I suspect that the results would not be forthcoming with ease. Experience seems to be the key to the best results... And dark skies.... And a whole lot of time.... And incredible processing skills!

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PhotoGav

PhotoGav

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Second attempt is a big improvement Gav, and despite what I said, you have actually got some pinks coming through now :)

I don't have a gallery, but can PM you some of my pics

Thank you! I have just posted my 'final' reprocess as a new thread. I'm much happier with it, but it still is far from the result I would really like to acheive.

Yes please, would love to see some pics - how does the PM thingy work?

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