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IC1396 NARROWBAND More data added.

SlipperySquid

By SlipperySquid
in Imaging - Deep Sky

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SlipperySquid

SlipperySquid

Posted
Posted

Elephants trunk nebula using astronomik narrow band filters.

Mapped SII=R HA=G OIII=B

Approx 180 mins of data in each channel taken in 10 minute slices.Darks Bias and flats added.

Imaging scope was the Megrez 72mm (the more I use this little scope the more impressed I become)

CCD was the Atik16hr.

Added an hour in each channel to the data I had taken a couple of weeks ago and reprocessed the colours so they are not as garish!

I would still like more structure showing in the trunk maybe if I up the subs to 20mins on the next run? or maybe it's the limits of the scope?

The extra hour's subs did add a bit more detail and I'm happier with the colour :D

Second image added for comparison with more noise left in!

post-17960-133877609991_thumb.jpg

post-17960-133877610009_thumb.jpg

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Psychobilly

Psychobilly

Posted
Posted

Nicely Done..

NR if its overdone reminds me of the days when you would smear vaseline over a filter to soften an image during a shoot...

If it obvious that you have done it then its overdone... I personally prefer to see a bit of "honest" noise :D

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martin_h

martin_h

Posted
Posted
Yeh, I like a bit of noise too.

But vaseline...really? Did peeps do that? :D

Yes and sometimes I used to breathe on the lens then look through the viewfinder and wait for it to clear to the right amount then hit the shutter button.....ahhhh the good old days:)

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Coco

Coco

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Wonderfully isolated target... nice indeed.. did you not need a flattener/reducer? or can the 285 chip manage to take advantage of the centre of this scope...

very nice indeed anyway :D

.

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ollypenrice

ollypenrice

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Not surprized you like the Megrez! Remarkable resolution for that aperture. I prefer the noisier version or might go for a compromize between the two, the de-noised one looking a bit buffed up to my eye.

Olly

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RobH

RobH

Posted
Posted

Great result Matt....I particularly like the colour.

Re. noise reduction, I agree that you've oversmoothed, but I can understand why given that you only have 3 hours of data for each channel....not really very much when talking about OIII and SII.....Shoot a bunch more to add to it and you'll find that you don't need any noise reduction.

18 subs per channel is just a starting point really.....you should at least double what you have.

Cheers

Rob

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SlipperySquid

SlipperySquid

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Wonderfully isolated target... nice indeed.. did you not need a flattener/reducer? or can the 285 chip manage to take advantage of the centre of this scope...

very nice indeed anyway :D

.

Cheers mate,

No flattener or reducer needed the scope and CCD seem to work really well together!

Thanks everyone for the comments really appreciate it and it's nice to get answers telling me what I'm doing wrong!

Rob, everyone knows you are the king of the Big Stack....or so I've heard :p but I will do as you command and build up the image with the next set of clear skies.....6 hours per channel you say ;) minimum...

Clear skies all,

Matt.

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RobH

RobH

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Hello Matt,

You can get away with a bit less Ha if you need to, but there's no substitute for lots of data, and I think that the image is worth it as it's great already. It does get a little dull shooting night after night of the same target, but once you start processing it all becomes worthwhile :D

Cheers

Rob

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Psychobilly

Psychobilly

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Posted

I used to try an pick a few different targets and get a couple of hours on each one each night.. Narrowband should be even easier than OSC or RGB as you don't have to worry about the moon so much...

It's definitely going to be worth it as its building very nicely indeed...

Peter...

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ollypenrice

ollypenrice

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Rob has hit it on the nail. The reward comes when you process and end up with a result that will last you for years. Time, time, time... and a fast f ratio. I once got told off on the French forum because I had used too much noise reduction. I hadn't used any. A good eye can see the difference.

Olly

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Tim

Tim

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Very nice Matt, love the colours :D

The little WO72 comes into its own with narrowband pics, the glass lets through a lot of juicy emissions data. Surprised you dont need a flattener though, and if you do add one, the scope will be faster too :p I swapped my WO72 for a Borg 77 last year, but I do miss the chunky little fellow.

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inksmithy

inksmithy

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I'm a complete novice to photography of any kind, let alone astrophotography, so I can't offer any constructive criticism at all. I'm not qualified.

What I can do is say how much I like the images, to my eyes the difference between the two versions NR is so subtle as to be almost unnoticeable on the device I'm using to view it.

Apart from that, lovely work, it looks like a fantastic subject and you have done some beautiful work on it.

It's funny, its called the Elephants Trunk, but I see a hooded humanoid with glowing eyes. I'll admit that doesn't have the same ring to it though.

Alan

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GordonH

GordonH

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Posted

I agree with what others are saying about the image, it is very nice and detailed. From the noise and noise reduction issues, it does look over smoothed and as a result some of the definition in the surrounding nebulous cloud is lost. In order to avoid these issues it is best to avoid any form of noise reduction as it does have adverse effects on the overall image.

In order to reduce the possibility of noise creeping into your images you need to shoot more data pure and simple, there is no other way around it. With narrow band imaging you are typically looking at a minimum of 4-5 hours data per filter for an f5 system (more if the system is slower). Also I would recommend that unless you have a super fast system of faster than f5 then your minimum length of exposure should be 20 minutes as this will give a better signal to noise ratio which will help keep the noise down. Finally make sure your raw frames are properly callibrated.

I use an f5 system and I do 30 minute exposures with a minimum of 4 hours per filter and I don't use any form of noise reduction in my processing. From a personal point of view I feel that the use of noise reduction is a short cut for not having enough data in the first place

Best wishes

Gordon

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