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Old 20-10-2018, 03:41 PM
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NGC 300 now with 13 hrs data

Managed another night under clear & dark skies to add data to last months post.
Extra data sure makes a difference! Wow, this thing is dim...

Big one HERE

Reckon another night (or two) would smooth it out further, but overall I'm pretty happy with this first attempt so far.... and hey, the core is yellow now too

That said, I'm curious as to how you folks do the initial stretch/combine on RGB data to get nice round, perfectly registered LRGB stars without halos etc.
Is there some secret voodoo ritual there that I need to be initiated into?

Your workflow suggestions would be most welcome

Cheers

Andy
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Last edited by Andy01; 20-10-2018 at 05:28 PM.
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Old 20-10-2018, 09:13 PM
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Quote:
Originally Posted by Andy01 View Post
Managed another night under clear & dark skies to add data to last months post.
Extra data sure makes a difference! Wow, this thing is dim...

Big one HERE

Reckon another night (or two) would smooth it out further, but overall I'm pretty happy with this first attempt so far.... and hey, the core is yellow now too

That said, I'm curious as to how you folks do the initial stretch/combine on RGB data to get nice round, perfectly registered LRGB stars without halos etc.
Is there some secret voodoo ritual there that I need to be initiated into?

Your workflow suggestions would be most welcome

Cheers

Andy
Really a very lovely NGC300 which is one of my favourite southern galaxies. I think its more photogenic than its cousin M33 in the northern hemisphere.

The yellow colour of a lot of the stars though seems off. Its too bright a yellow. Perhaps some adjustment needed there?

Lots of detail.

I don't see much halo around the stars though. Which ones are you referring to? Star halos are a bit of a problem with astro processing - I agree. Its something I have had trouble with.

If its not hardware connected (poor quality glass in the corrector lens etc) and you are using good filters then I would look to 2 possibilities. One is the well depth of the sensor. The 8300 well depth is not that great so getting the right exposure length so the wells are not full and overflowing and the outer rings of the star don't expose too much. I found star blooming/halos most prominent with a 694 sensor which had relatively small wells. Overstretching the stars will do it too - usually in the RGB images. Blue often is the least sharp.

Greg.
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Old 21-10-2018, 09:12 AM
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Nice one, Andy! There's no substitute for heaps of data on dim galaxies

Looks like you have a little misregistration between the channels? I don't know of any magic incantation that will give you perfect stars. It's a matter of getting everything you can right at capture and data prep time and then hiding any remaining warts later in processing

As Greg said, halos are pretty common. Careful focus and control of dynamic range will help but it's harder to deal with causes related to the optics.

Cheers,
Rick.
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Old 21-10-2018, 12:00 PM
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That looks good Andy.
Martin
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Old 25-10-2018, 10:23 PM
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Originally Posted by gregbradley View Post
Really a very lovely NGC300 which is one of my favourite southern galaxies.

I don't see much halo around the stars though. Which ones are you referring to? Star halos are a bit of a problem with astro processing - I agree. Its something I have had trouble with.

If its not hardware connected (poor quality glass in the corrector lens etc) and you are using good filters then I would look to 2 possibilities. One is the well depth of the sensor. The 8300 well depth is not that great so getting the right exposure length so the wells are not full and overflowing and the outer rings of the star don't expose too much. I found star blooming/halos most prominent with a 694 sensor which had relatively small wells. Overstretching the stars will do it too - usually in the RGB images. Blue often is the least sharp.

Greg.
Cheers Greg- Exposure length appears to be largely guesswork for me in my recent forays into LRGB imaging.
I remember Ray (Shiraz) posted a conplex formula to define exposure times a while back but it went way over my head.
I’ll trial shorter exposures next time, with my 8300 chip- but I don’t want to be caught out mucking about under precious dark sky time for too long!
I wonder if folks here just do a ddp stretch or a more considered process of levels & curves prestretching when processing?

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Originally Posted by RickS View Post
Nice one, Andy! There's no substitute for heaps of data on dim galaxies

Looks like you have a little misregistration between the channels? I don't know of any magic incantation that will give you perfect stars. It's a matter of getting everything you can right at capture and data prep time and then hiding any remaining warts later in processing

As Greg said, halos are pretty common. Careful focus and control of dynamic range will help but it's harder to deal with causes related to the optics.

Cheers,
Rick.
Thanks Rick!
I’m attempting to eliminate variables one by one- hoping it’s not a hardware issue. But seeing Steven Mohr’s wonderful Insight competition Galaxy winning image really does make me wonder what difference a Planewave vs GSO scope makes?
They’re both just comprised of mirrors, not glass - so surely it’s not like a Tak vs Skywatcher refractor optics thing?

I reckon there’s a consideration for different exposure times between R & G,B that’s contributing to the misregistration issue too?

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That looks good Andy.
Martin
Cheets Martin- reckon it’s about as good as I can get with my current skills & gear- thanks for the feedback!

(Was getting worried- could here crickets chirping here!)
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Old 26-10-2018, 04:45 PM
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[QUOTE=Andy01;1401884]Cheers Greg- Exposure length appears to be largely guesswork for me in my recent forays into LRGB imaging.
I remember Ray (Shiraz) posted a conplex formula to define exposure times a while back but it went way over my head.
I’ll trial shorter exposures next time, with my 8300 chip- but I don’t want to be caught out mucking about under precious dark sky time for too long!
I wonder if folks here just do a ddp stretch or a more considered process of levels & curves prestretching when processing?


Short exposure stacked images suits cameras with very low read noise like these CMOS ASI ZWO cameras. CCD cameras require longer exposures.

Also I would argue that exposure length is more determined by your mounts tracking accuracy than anything. Start doing too long and stars can get eggy.

My comment really was only to keep an eye on exposure length if you are getting too much haloing around brighter stars. Its one factor you can control. But I don't see much haloing in your image and neither do I see issues with the many fine 8300 images around.

The Sony 694, 814 sensors are starting to get very low well depth so it potentially is more of an issue. Again I think it depends on your scope and perhaps your processing workflow as I don't see the halo issue with Mike's use of that camera sensor compared to what I was getting.

Greg.
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Old 26-10-2018, 05:59 PM
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Please, this is not to be taken the wrong way. Excellent photos are not a simple process. It’s not a Planewave vs GSO either as galaxies often occupy a smaller part of the chip’s FOV. The majority of the work of a truly excellent photo comes down to the skillset, and attention to detail when constructing their image. There is no magic button here. LRGB imaging takes time and skill. Half-baked colours with the excuse of artistic licence don’t apply with excellent LRBG work. Again, this is just an observation.
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Old 26-10-2018, 09:41 PM
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[QUOTE=gregbradley;1401957]
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Originally Posted by Andy01 View Post


Short exposure stacked images suits cameras with very low read noise like these CMOS ASI ZWO cameras. CCD cameras require longer exposures.

Also I would argue that exposure length is more determined by your mounts tracking accuracy than anything. Start doing too long and stars can get eggy.

My comment really was only to keep an eye on exposure length if you are getting too much haloing around brighter stars. Its one factor you can control. But I don't see much haloing in your image and neither do I see issues with the many fine 8300 images around.

The Sony 694, 814 sensors are starting to get very low well depth so it potentially is more of an issue. Again I think it depends on your scope and perhaps your processing workflow as I don't see the halo issue with Mike's use of that camera sensor compared to what I was getting.

Greg.
Ok, thanks Greg- Some intriguing thoughts to ponder on there. Cheers 😊

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Half-baked colours with the excuse of artistic licence don’t apply with excellent LRBG work.
Ouch!
Anyway, have a nice weekend...
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Old 27-10-2018, 09:32 AM
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Originally Posted by CosmicEcho View Post
Please, this is not to be taken the wrong way. Excellent photos are not a simple process. It’s not a Planewave vs GSO either as galaxies often occupy a smaller part of the chip’s FOV. The majority of the work of a truly excellent photo comes down to the skillset, and attention to detail when constructing their image. There is no magic button here. LRGB imaging takes time and skill. Half-baked colours with the excuse of artistic licence don’t apply with excellent LRBG work. Again, this is just an observation.
That's a little harsh. Have a look at the tone of the bulk of the posts on this site and you'll see they are more encouraging than this.

You may not know but Andy has won several awards for many of his fine astro photos and regularly sets the bar for what is achievable from suburban locations.

Greg.
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Old 27-10-2018, 11:29 AM
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This is actually not a bad result. It is a very dim face on galaxy and requires good integration and a lot of it in the colour and the lum. I think it took something like 18 hours to get a decent image myself and I would still look more data on it now.

It looks a little like you have used the minimum filter at some point on the galaxy and the stars. I think this has affected the detail level in the galaxy itself more than the stars. 13 hours of data should give you something a little cleaner. However, I think if you went back and gave it another go from scratch you might be surprised by the results you obtain.

I agree this is not necessarily an equipment related issue. Steven told me it took many months to sort out the collimation on that CDK and remember he is also in a remote setting. He can afford to drop data that is sub standard. The GSO scopes are more than capable but I think maybe your collimation might need just a little tweak to get better results than you already have here. Other issues might be present too. Some of my best images have been taken on my RC12 which took years to tweak out with collimation. Having washed that mirror now I am now going through the process again to get collimation right.
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Old 27-10-2018, 04:43 PM
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Originally Posted by gregbradley View Post
That's a little harsh. Have a look at the tone of the bulk of the posts on this site and you'll see they are more encouraging than this.

You may not know but Andy has won several awards for many of his fine astro photos and regularly sets the bar for what is achievable from suburban locations.

Greg.
Thanks Greg - it's ok, I can live with the odd trolling, but I appreciate your support

Quote:
Originally Posted by Paul Haese View Post
This is actually not a bad result. It is a very dim face on galaxy and requires good integration and a lot of it in the colour and the lum. I think it took something like 18 hours to get a decent image myself and I would still look more data on it now.

It looks a little like you have used the minimum filter at some point on the galaxy and the stars. I think this has affected the detail level in the galaxy itself more than the stars. 13 hours of data should give you something a little cleaner. However, I think if you went back and gave it another go from scratch you might be surprised by the results you obtain.

I agree this is not necessarily an equipment related issue. Steven told me it took many months to sort out the collimation on that CDK and remember he is also in a remote setting. He can afford to drop data that is sub standard. The GSO scopes are more than capable but I think maybe your collimation might need just a little tweak to get better results than you already have here. Other issues might be present too. Some of my best images have been taken on my RC12 which took years to tweak out with collimation. Having washed that mirror now I am now going through the process again to get collimation right.
Yeah good feedback there Paul & thanks for your insights. I'm really not used to having an instrument that I have to fiddle with to make it work as it's supposed to (I also appreciate that you've been to hell & back with your recent experience with the Orion Optics Newt).

I used your excellent NGC 300 as a benchmark during my capture/processing & appreciate that mine's got further to go - although very comfortable with NB imaging I'm new at this LRGB caper and so am quite willing to go back to square one to get the fundamentals right.

I found this useful tutorial online today and this is exactly the kind of info I'm looking for - https://stargazerslounge.com/topic/2...maging-primer/

I have both VicSouth & Snake Valley coming as a dark sky double header on consecutive weekends so very happy to get as much useful feedback as possible beforehand.

Cheers
Andy
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Old 30-10-2018, 09:56 PM
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Quote:
Originally Posted by CosmicEcho View Post
Excellent photos are not a simple process. The majority of the work of a truly excellent photo comes down to the skillset, and attention to detail when constructing their image. There is no magic button here. LRGB imaging takes time and skill. Half-baked colours with the excuse of artistic licence don’t apply with excellent LRBG work.
Quote:
I guess this is why they are called opinions. When I look at RGB images, I can only see a huge amount of variation. Some excellent, and others, not. Same is true for narrowband. Some are truly excellent, and others,
The same standards hold true for both. They should contain a result that is pleasing to look at, illustrate an element of depth and clarity, with a final realistic rendition. Not some awkward attempt and call it creativity. not….

Well, well - It appears that this user has never posted an image here.
Interesting considering their strong opinions on what’s ‘right’.
May I suggest putting your money where your mouth is.
Let’s all see you show your imaging hand here that we might all learn & benefit from your own no doubt vast experience.

Last edited by Andy01; 30-10-2018 at 10:23 PM. Reason: Typo
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