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Old 04-09-2013, 03:05 PM
johnnyt123 (John)
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LRGB Processing problem.

Hi All..

My first stem into LRGB imaging has begun with the arrival of my new QSI 683wsg-8 which arrived last saturday.
it has LRGB Astronomik filters and Astrodon Ha, SII, OIII filters.

Now i have no experience in image acquisition or processing when it comes to LRGB so i am hoping all you those experts among you can give me a few tips.

I quickly imaged the Horse head 2 nights ago exposures were single subs as folows:
L: 8 min
R: 3 min
G: 3 min
B: 3 min
Ha: 5 min

What i notices that in Ha the stars are very tight but in RGB they appear more wholesome or fat. are they blown out or is this blooming...???
How do i stop this happening?
Also i dont know how to incorporate Luminance into my images in Photoshop CS6 or Ha as luminance.

What software for processing do you all recommend? is Pixinsight worth it?

Any further advise would be greatly appreciated.

Also Deep Sky stacker cant seem to stack my Narrow Band subs.
I can see countless stars but it for some reason can only see 10 or so and cant stack. Help please...

Please find attached the combined RGB (No luminance) and the Ha single shot 5 min exposure..

Thanks John
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  #2  
Old 04-09-2013, 03:31 PM
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alocky (Andrew lockwood)
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Firstly - given the relatively short integration time, that's a pretty good effort. Stars are usually tighter in NB subs because the spectra of a star is a continuum, so relative to the nebulosity they won't saturate as fast in Ha. What is not clear from your post is how you are focusing- this usually needs to be done for each filter, and can be very trying to perform manually. This, apart from guiding performance, is what makes stars fatter than they need to be.
I like pixinsight, there are heaps of other packages of varying merit, and I would say look at them all and play with a trial version before deciding. Ps is still the dominant tool of the current masters of this art.
Cheers,
Andrew.
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Old 04-09-2013, 03:46 PM
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naskies (Dave)
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Quote:
Originally Posted by johnnyt123 View Post
Hi All..

My first stem into LRGB imaging has begun with the arrival of my new QSI 683wsg-8 which arrived last saturday.
it has LRGB Astronomik filters and Astrodon Ha, SII, OIII filters.
Hooray!

Quote:
Now i have no experience in image acquisition or processing when it comes to LRGB so i am hoping all you those experts among you can give me a few tips.

I quickly imaged the Horse head 2 nights ago exposures were single subs as folows:
L: 8 min
R: 3 min
G: 3 min
B: 3 min
Ha: 5 min
Ha is only a narrow part of the full spectrum of R, so you'll need much longer subs to get a reasonable exposure. Many people use subs of 15 - 30 mins length - it depends upon your tracking, histogram, etc.

Quote:
What i notices that in Ha the stars are very tight but in RGB they appear more wholesome or fat. are they blown out or is this blooming...???
How do i stop this happening?
It's happening for two reasons. First, your LRGB subs are pretty out of focus - this gives you bigger stars because the light is spread out across a larger area. Your Ha exposure has much better focus - the nebulosity is sharp, stars are nice and tight, and you can see diffraction spikes in the bright star Alnitak. (Note how the diffraction spikes are missing from your LRGB image.)

Did you re-focus between filter changes? Most filters will have slightly different focus positions, so if you used the Astrodon Ha filter to focus and then switched to Astronomik RGBs, they'll most likely all be out of focus. Some manufacturers claim that their filters are "parfocal", i.e. have the same focus distance, like Baader does with my LRGBHaOIIISII set - but when I actually measure them they differ by tiny amounts.

Second, as Andrew points out narrowband filters will suppress a lot of star light and therefore stars will naturally be smaller. In this case, it's mainly a focus issue.

Quote:
Also i dont know how to incorporate Luminance into my images in Photoshop CS6 or Ha as luminance.
Here's a step-by-step guide:

http://starizona.com/acb/ccd/software/ps_lrgb.aspx

In fact, the entire Guide to CCD Imaging is well worth reading:

http://starizona.com/acb/ccd/ccd.aspx

Quote:
What software for processing do you all recommend? is Pixinsight worth it?

Any further advise would be greatly appreciated.

Also Deep Sky stacker cant seem to stack my Narrow Band subs.
I can see countless stars but it for some reason can only see 10 or so and cant stack. Help please...

Please find attached the combined RGB (No luminance) and the Ha single shot 5 min exposure..

Thanks John
You probably have the threshold set too high - on the register images dialog, there's a second tab where you can set the threshold. In narrowband subs, the histogram is often bunched to the left (especially in your case with short Ha subs) so you'll need to drop the threshold way down to say 5%.
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Old 04-09-2013, 07:42 PM
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White Rabbit
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I feel your pain John. I'm on the same journey.

I have some beautiful Ha stuff but I'm really struggling with the rgb component, specifically with bloating in my blue channel despite focusing after each filter change.
I have the Astronomic filters and they are meant to be parfocal but they arnt. Do yourself a favor and get a focuser from Moonlight or Feather Touch that focus for you. It saves so much time and frustration. If you can work out what the difference is you can set most focusers to allow for the off set. I've yet to figure that part out.

All the best.
Sandy
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Old 04-09-2013, 09:11 PM
johnnyt123 (John)
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Hi again.

Thanks for those who have replied thus far.

Andrew - I have to admit that i still have to perfect my alignment and tracking efforts. currently i seem to get to within 10 arcminutes Mel and Maz of SCP and seem to settle there.

Dave - I focus manually using the Luminance filter. i havent refocussed when changing filters and neither when switching to NB filters from LRGB. So i guess it might be worth while getting a Moonlite focuser to automate the process. unfortunately 15-20 min guiding at this time is out of reach for me with out field rotation.

I tried setting up this the QSI 683wgs-8 camera on my Celectron C8 which has a Moonlite focuser but unfortunately there was too much flexure in the image train that made all the stars appear tear drop shaped so i opted not to use the C8 for imaging for the time being.

Sandy - We essentually have the same camera with the KAF8300 sensor. its a great camera so i guess its we need to hang in there to bring it to its full potential.

Thanks for those links Dave.

Take care guys....
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Old 06-09-2013, 12:01 PM
johnnyt123 (John)
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I am having a few more issues with aligning the LRGB images.

and i am not referring to the alignment in " Levels" but rather the physical overlaying of the images.

When i select the individual channel in Photoshop it wont let me move each channel individually.

Please see the images i have attached to illustrate what i mean.

What software is able to align the individual LRGB images to be perfectly overlayed in photoshop?

Thanks again
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Click for full-size image (Untitled1.jpg)
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Old 06-09-2013, 12:36 PM
jase (Jason)
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What? Aligning the individual L,R,G,B subs using Photoshop. Taking the hard road. You'll need to be super proficient at the transform tool in PS to achieve this as the frames will also require skewing in order to match. You'll lose some hair in the process too.

You need to get other software, not photoshop, to do the grunt work of imaging alignment. Software such as PixInsight or MaximDL or CCDStack or MiraAP or AstroArt, CCDSoft or IRIS, etc, all have this capability. Deep Sky Stacker can also do this but you mentioned it failed for you. Perhaps investigate further or ditch the freeware for something more feature rich if you want to step up your output quality.
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Old 06-09-2013, 01:03 PM
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Second the advice not to align your images in PS! Bad idea! Anyway, you are going to eventually want to calibrate your images (darks, flats, bias), and stack multiple subframes- don't try this in PS either. Pixinsight is a great tool for this, Nebulosity is a cheaper tool (which can drive the camera too), and DSS is free. Good evidence here that you get what you pay for! Other software has been mentioned, and all of those packages have also been used to produce good images.
Cheers,
Andrew.
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Old 06-09-2013, 03:02 PM
johnnyt123 (John)
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I think i might get Pixinsight.

PS6 is a headache. Cant even process 32bit images with it. the only thing i can adjust is Levels. have to always convert to 16bit mode and images arent as crisp....

DSS Cant align RGB with out stacking them (I am already losing hair over this). It also couldnt find enough stars (even with threshold at 2%) to stack narrow band captures.

CCDsoft was ok and able to stack narrowband images

I havent tried aligning using maxim DL yet

I havent given up yet. But at this rate...might put my newly purchased camera for sale.......lol

Thanks guys.

John
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Old 06-09-2013, 05:59 PM
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Quote:
Originally Posted by johnnyt123 View Post
I think i might get Pixinsight.
You can request a free 60 day trial from their website. Fair warning though - the user interface it's less intuitive than DSS/PS, but I'm finding it really great

Quote:
PS6 is a headache. Cant even process 32bit images with it. the only thing i can adjust is Levels. have to always convert to 16bit mode and images arent as crisp....
Yes, that's annoying but no major drama since camera images are only 16-bit anyway. You can apply curves to 32-bit images in PS during conversion to 16 bit mode. (PI is much, much better in this regard.)

I find that it works better to non-linearly stretch images in DSS first before loading into PS. For RGB images, just apply the same stretch to each channel and then combine the mono images in PS.

Quote:
DSS Cant align RGB with out stacking them (I am already losing hair over this).
Yes, it can. Add your reference frame as a light frame, then go through the registration step. Right click on it, set as reference frame, and de-select it. Next, add all the frames that you want to align as light frames. Select Create a registered/calibrated file for each light frame in the Intermediate Files tab, and disable Create output file in Output. Just run through the full registration/calibration process and you'll get a aligned frame. Alternatively, you can stack just one frame at a time using the standard process.

What you probably actually want to do is to use the same reference frame for each channel. This way, your output files for each colour will be already be aligned when you load them into PS.

Quote:
It also couldnt find enough stars (even with threshold at 2%) to stack narrow band captures.

CCDsoft was ok and able to stack narrowband images

I havent tried aligning using maxim DL yet
Your Ha subs are very short - there won't be much contrast between the stars and background. Have you run a full calibration of darks / flats / dark flats? This should help.

Quote:
I havent given up yet. But at this rate...might put my newly purchased camera for sale.......lol
Yes, astro imaging is great for learning how to endure endless pain and frustration

Just be patient, stick with it, aim to take it one step at a time, and you'll get there in the end
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Old 06-09-2013, 08:41 PM
LewisM
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Thanks Dave - the Starizona page is an ENORMOUS help for me, especially now I am getting back the ST8XE I foolishly sold off
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Old 06-09-2013, 08:49 PM
johnnyt123 (John)
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Dave

I can't say how much I appreciate your feedback.
Hopefully in time my skills with astro imaging will resemble yours.

First thing I am going to do is purchase a moonlite focuser for my Megrez to automate the focusing process when changing between filters.
I assumed when Astronomic and Astrodon say their filters are par focal then one would assume they are truly par focal. But this is not the case. One mistake I made was focusing using the luminance filter then assuming the RGB filters are at the same focal length.
Assuming the filters are perfectly flat and the surfaces are parallel I don't understand how the light is being refracted changing the focal length. So I also assumed the all the filters would be parfocal.

Secondly after the focuser if installed I will get Pixinsight and have the pleasure of getting to know how to use it and lose more hair over it.

Thanks again Dave.
Take care

John.
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Old 06-09-2013, 10:42 PM
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Quote:
Originally Posted by johnnyt123 View Post
Dave

I can't say how much I appreciate your feedback.
Hopefully in time my skills with astro imaging will resemble yours.
No worries, John. I'm only a few months ahead of you... having bought my first CCD only 10 months ago

Quote:
First thing I am going to do is purchase a moonlite focuser for my Megrez to automate the focusing process when changing between filters.
I assumed when Astronomic and Astrodon say their filters are par focal then one would assume they are truly par focal. But this is not the case. One mistake I made was focusing using the luminance filter then assuming the RGB filters are at the same focal length.
Assuming the filters are perfectly flat and the surfaces are parallel I don't understand how the light is being refracted changing the focal length. So I also assumed the all the filters would be parfocal.
When I say "not parfocal", I'm talking really really tiny amounts. Without a motorised focuser and software-assisted measurement of star sizes - I highly doubt you'd be able to tell the difference. Notice how your out of focus stars all look equally out of focus in R, G, and B?

It looks to me very much like you accidentally focused with your Astrodon Ha filter instead of Astronomik L. I get similar results if I focus with my Astrodon Ha and then try to shoot images with my Baader LRGB filters.
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Old 07-09-2013, 02:39 PM
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I will just add my 2 cents worth here as I'm only a bit over a year into processng images.

I started out using CCDSoft to stack and combine RGB. That was only marginally OK. The stacking worked OK most of the time but RGB was a mess and never very successful. Often after a combine the resulting image could not be saved. I posted the problem at Software Bisque and never got a satisfactory answer.

Now, I've never used Pixinsight so this is just rumor and 2nd hand. No doubt it is very good, but it is as deep or deeper than Photoshop and has a most unintuitive interface so I'm told. At the recent AAIC it was discussed quite a bit and was mentioned that one initially just had to religiously follow tutorials to get any result. I have no doubt that one could master it but I really question if one should start with it. An accomplished imager/processor I'm sure could get a result "better" than some other software (maybe), but a beginner...well, I'm doubtful so why make life harder? This hobby is already really hard and quite humbling!

Instead I chose CCDStack and the tutorials by Adam Block. It is pretty intuitive and gives quite good results. There is a free trial and I would really suggest you give it a go before rejecting it. I do all my stacking there and then produce RGB. You can align luminance to the RGB, then move into Photoshop to add the luminance. Since you aligned in CCDStack a simple paste is all that is required. Photoshop is great for finishing images once they are stacked. There are several plugins that help very much such as Noise Ninja and Gradient Exterminator and several others. Once you master masks you will see real results! That is where I found Adam Block's tutorials absolutely indispensable.

Good luck!

Peter
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Old 08-09-2013, 12:03 AM
johnnyt123 (John)
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Thanks Peter. I wil definately give ccdstack a go.

Hey Dave. Didn't you have a William Optics FLT132 for sale at some point in time?

Would you still consider selling it?

Thinking of upgrading my Megrez 110.

John
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Old 09-09-2013, 04:38 PM
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I second Peter's advice. Adam Blocks Tutorials are very very good. I would recommend you get them and follow them as you go through the learning curve of learning Photoshop and CCDstack.

CCDstack has gone through an evolution. It was quite a simple program initially but it seemed to handle memory very poorly so if you used a larger camera sensor it bogged down quickly. It was not an issue with the smaller sensors that made smaller files.

The later versions seemed to improve in that regard. The latest version I find a bit annoying at times in that the added complexity gets in the road of simply operations but I note there are added functions that it did not hace before. Its still a great program. I find some programmers make things easy to understand and intuitive. CCDstack is not quite like that. Its not that hard either. For example it does not come with a comprehensive set of instructions as far as I know so you have to rely on someone like Adam Block to pump out some tutorials.

Adam steers you through Photoshop very well.

Greg.
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