Go Back   IceInSpace > Images > Deep Space

Thread Tools Rate Thread
Old 29-08-2020, 06:27 PM
FrancoRodriguez (Franco)

FrancoRodriguez is offline
Join Date: Mar 2019
Location: Ramsay, SE QLD
Posts: 66
yet another helix nebula

Hi All, here's my rendition of the helix nebula. It definitely goes into the "purty pitchers" category, certainly not an unadulterated pure science image, but I wanted something that looked nice because I'm pretty new to pure narrowband imaging.
I went pretty deep with around 50 x 20 minute exposures in order to get the outer wisps in Ha. I used Ha luminance layer and red channel, oxygen for blue and green, and sulphur for green too (not many sulphur photons).
Weighted batch preprocessing in pixinsight
the rest done with layers in PS and LR
Attached Thumbnails
Click for full-size image (untitled.jpg)
206.3 KB142 views
Reply With Quote
Old 30-08-2020, 06:04 AM
Placidus (Mike and Trish)
Narrowing the band

Placidus is offline
Join Date: Mar 2011
Location: Euchareena, NSW
Posts: 3,545

First up, the depth is amazing! You've got the largest of the super-faint outer chevrons, and the still-fainter ones are starting to show. Excellent bordering on remarkable.

Mapping H-alpha to red and OIII to blue-green is legit and solid.

Using H-alpha as a luminance layer is fraught with traps. The most obvious is any area that is a pure lovely brilliant OIII with no H-alpha will come out black.

You mentioned that the SII was scanty, and that makes it hard (but not impossible, given the great depth you've achieved) to do an SHO rendition without ending up with bloated red rings round the stars from the SII.

One very labour intensive way around (routine for us for all narrowband images) is to separate the image into stars and nebulosity. You can then process the stars and the nebulosity (which is the important thing!) completely separately, getting the colour balance right in the nebulosity, applying sharpening and then reassembling (just adding the two together again).

Much quicker and easier (but not our favourite approach): I'd suggest that you either scrap the SII, or perhaps map it to its natural red if you don't want to throw it out, and you'll have a nice almost-natural-colour narrowband image.

Very best,Mike
Reply With Quote
Old 30-08-2020, 09:09 AM
Cosmic's Avatar
Cosmic (Daniel)
Registered User

Cosmic is offline
Join Date: Oct 2010
Location: Darwin NT
Posts: 334
Nice work Franco, big fan of the outer nebulosity captured.
Reply With Quote
Old 30-08-2020, 05:26 PM
FrancoRodriguez (Franco)

FrancoRodriguez is offline
Join Date: Mar 2019
Location: Ramsay, SE QLD
Posts: 66
I really appreciate the feedback. HSO is very new to me (I've usually just enhanced OSC images with narrowband data). It's a lot harder than I had imagined. I think I understand what you mean regarding Ha as luminance. Would one way around the problem be to make two images, One with Ha lum layer and the other without, and get those two separate images, make them layers themselves and use one of the purely additive blending modes? I'm not happy with the lack of detail in the inner portion of the image. I lost a lot of the subtle oxygen radial streaming data. It's all pretty new to me. can I show you the original mono images?
Reply With Quote
Old 30-08-2020, 05:33 PM
FrancoRodriguez (Franco)

FrancoRodriguez is offline
Join Date: Mar 2019
Location: Ramsay, SE QLD
Posts: 66
Here they are. I put them through masked stretch and linear fit. How would you recommend I improve the streaky oxygen (Bok globule?) data? I had to compress the hell out of the files to 1mb otherwise it wouldn't let me upload them
Attached Thumbnails
Click for full-size image (ha.jpg)
224.7 KB47 views
Click for full-size image (o3.jpg)
244.6 KB35 views
Click for full-size image (s2.jpg)
257.3 KB31 views
Reply With Quote
Old 02-09-2020, 06:11 PM
codemonkey's Avatar
codemonkey (Lee)
Lee "Wormsy" Borsboom

codemonkey is offline
Join Date: Jul 2013
Location: Kilcoy, QLD
Posts: 2,049
Nice work Franco, you brought out a lot of very faint detail there!
Reply With Quote
Old 02-09-2020, 08:06 PM
Registered User

topheart is offline
Join Date: Nov 2005
Location: Cairns
Posts: 1,061
Very nice!
Wonderful faint stuff there!

Reply With Quote
Old 07-09-2020, 09:29 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
Join Date: Aug 2015
Location: Sydney
Posts: 1,507
There's a lot of getting detail coming through. Well done!
Reply With Quote


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT +10. The time is now 03:04 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Limpet Controller
NexDome Observatories
Astronomy and Electronics Centre