The faint emission nebulae and overlapping open cluster of IC1848 resides in the constellation Cassiopeia. It is commonly known as the Soul or Baby nebulae, due to the nebulosity displaying the contours of what appears to be a foetus.
When imaged through narrowband filters, it is evident that the nebulosity characteristics contains more than energised hydrogen. The subtle blue hues indicate oxygen (OIII), while the red and green hues show sulfur (SII) and hydrogen (Ha) respectively. Present near the top of the foetus head is the bright nebulae IC1871, while the open cluster dots the foetus stomach. The nebulae is estimated as being 6,500 light years distant.
About the image;
Total exposure time of 6 hours (SII:120min;Ha:120min;OIII:120min) using 15min subs for all exposures. I found the SHO “Hubble palette” displayed the object better than HOS and other permutations, so SHO was mapped to RGB respectively. For those who aren’t familiar with narrowband imaging, the individual filters (SII, Ha and OIII) display specific emission lines providing an insight into the gaseous characteristics of the nebula. SII (672nm) is Singly ionised Sulfur, Ha (656.3nm) is Hydrogen alpha and OIII (500nm) Doubly ionised Oxygen. The joys of a monochrome chip. This is my first “serious” attempt at narrowband imaging. I don’t believe it will be my last, but I underestimated the quantity of work compared to RGB imaging (and it’s variations such as HaRGB etc). In some ways it’s easier as there are no correct methods for balancing the colours, but to deliver the desired result takes time. Overall, I’m pleased with the final output.
Image processing;
Well, what I know about RGB image processing goes out the window. All subs calibrated/reduced in MaximDL (dark/flat/bias/hot and dead pixel removal). Subs registered in Registar and Sigma Rejected back in MaximDL before saving as tiffs. Loaded on channels (SII,Ha and OIII) in PS, the applied levels and curves. Created clipping masks per channel for greater colour mapping control (see below attachment). Clipping masks are nothing new and are extremely flexible. This is defined in section B.3.1 of the “Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images” by Travis Rector. Each mask contains a colour mapping (hue/saturation) and levels for fine adjustments. After reaching the optimal mapping distribution, I added a new deconvoluted Ha channel as the luminance at 100% opacity. Typical of narrowband images, the stars appear to go a purple tone. Many just leave this, but I find it detracts from the image depending how deep they go. To counteract this, I used a separate luminance channel as a new layer which was blended using the lighten mode and stretched using curves. This brought the stars back to a whiter tone. I thought about using the original balanced RGB palette for the stars, but this didn’t appeal pleasing to me. SII, Ha and OIII layers flattened, then Gaussian blur of 3 pixels applied – this smoothed the hue transitions between the specific wavelengths. A minor adjustment to boost the red balance (up mid-tone +2). All layers flattened. Minor adjustments to levels and saturation before finalising.
I thoroughly enjoyed working on this image. Watching it progressively development through the processing workflow. I hope you enjoy it too. Thanks for looking.
Excellent Jase, I'm a big fan of colour mapping in narrowband the colours and details it brings out are superb in my books and your image is a perfect example of this.
I have yet to purchase OIII and SII filters and do my own but looking at your image just made up my mind, I have a holiday bonus coming up and I know where that is going.
As always an incredibly detailed image, i could probably fill a page with the good details, ...... not particularly keen on the red halos around the stars in the centre of the nebula though...... still a stunning image and currently way beyond anything i have yet done.
That looks just excellent, well done it is an joy to look at this picture.
Cheers Martin. Appreciate it.
Quote:
Originally Posted by DavidU
Crikey awsome detail, 6 hours !!!
Thanks David.
Quote:
Originally Posted by Ric
Excellent Jase, I'm a big fan of colour mapping in narrowband the colours and details it brings out are superb in my books and your image is a perfect example of this.
I have yet to purchase OIII and SII filters and do my own but looking at your image just made up my mind, I have a holiday bonus coming up and I know where that is going.
Very spectacular.
Cheers Ric. Indeed narrowband imaging adds that extra dimension to the imagination. The palette dictates what you plan to convey in the image. As mentioned, I settled for the SHO pallet (Hubble pallet), but also have a HOS image (Canada-France-Hawaii Telescope – CFHT pallet) which is remarkably different - personally HOS is not all that aesthetic, but what is in the narrowband world when we are trying to display the nebulae characteristics? The Ha data on this object is a killer. Really smooth. Tempting to simply process that alone. I hope you get your filters soon. Despite some of the complexities, I'm surprised their aren't many people in these forums doing narrowband work. I know Fred and Bert do, but not many others. Its an ideal form of imaging urban locations hindered by light pollution. Anyway, thanks for your comments.
Quote:
Originally Posted by Alchemy
As always an incredibly detailed image, i could probably fill a page with the good details, ...... not particularly keen on the red halos around the stars in the centre of the nebula though...... still a stunning image and currently way beyond anything i have yet done.
Thanks Alchemy. Agree, the stars in narrowband images aren't pleasing, but after all, narrowband imaging is about acquiring the specific/narrow wavelengths of nebulosity not about getting pretty stars! Take a look around at other narrowband work and you'll see similar results. There are of course way to deal with this through processing.
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Just in case you thought I made up the title "“Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images” - you can download the document from my website. Its under the resources section (2.9Mb PDF document). If you're serious about imaging and image processing, it's worth understanding the principles defined in this document. Who knows, you may even learn something
Beautiful Jase! doesn`t it look so different remapping the colors. Helps bring out detail that is not so obvious in the original version..
I had a go at remapping the color channels in my pics and it was quiet fun and a good learn! but without narrow band filters its not the same!
Thanksyou for another fantasic image!
cheers
fantastic photo!!!!
are you sure that wasn't taken by hubble?
lovely photo, fantastic processing!
Thanks for the comment Joshman. Not the hubble, just a humble Tak FSQ106ED.
Quote:
Originally Posted by Garyh
Beautiful Jase! doesn`t it look so different remapping the colors. Helps bring out detail that is not so obvious in the original version..
I had a go at remapping the color channels in my pics and it was quiet fun and a good learn! but without narrow band filters its not the same!
Thanksyou for another fantasic image!
cheers
Thanks Gary. Yes, narrowband certain brings out the hidden details and gives the image greater depth.
Quote:
Originally Posted by JohnG
Hi Jase
Once again, another brilliant shot, can't wait to get back into imaging when the ST4000XCM arrives.
Cheers
Thanks John. I look forward to seeing some of your ST4k work when you're ready.
Quote:
Originally Posted by tornado33
Excellent.
The variations in colour emissions are striking from the edges to the interior of the nebula.
Scott
Thanks Scott!
Quote:
Originally Posted by rally
Thanks Jase,
Inspirational.
Many thanks for the PDF link - a terrific article, I can see this becoming a reference for future use.
Cheers Rally
Pleased you liked it Rally. Enjoy the image processing article. It opens up many possibilities.
Incredible image Jase. Your previous image was great, but the colour mapping has brought out even greater detail and is really spectacular.
Thanks Barb and David. Pleased you like it. I think narrowband imaging is rather subjective. Lets just say its not everyone's cup of tea. An acquired taste perhaps. I do agree though, the individual filters really bring out some exquisite details. Thanks again.
Quote:
Originally Posted by spearo
WOW !
breathtaking shot!
frank
Cheers Frank
Quote:
Originally Posted by EzyStyles
oh my goodness jase! that is hubble !. fantastic shot. i love it alot.
Thanks Eric. Perhaps I've influenced a few people to give this type of imaging a go. Quite technically challenging, but rewarding.
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Thanks again to all those who have commented. Much appreciated.
awsome detail, 6 hours !!!
The Ha data on this object is a killer. Really smooth. Tempting to simply process that alone. I hope you get your filters soon. Despite some of the complexities, I'm surprised their aren't many people in these forums doing narrowband work. I know Fred and Bert do, but not many others. Its an ideal form of imaging urban locations hindered by light pollution. Anyway, thanks for your comments.
