StarTools

Hello team,

Have seen multiple posts on similar topic but still unsure how to properly do this so hoping to get guidance.

Working on the Western Veil, captured 9hrs with L-Extreme and 2hrs with L-Pro; get nice result creating L-Extreme bi-color HOO / H(H+O)O using Compose module but now want to add RGB from L-Pro to improve star colors, with a "Documentary" result.

Is the following flow correct? I am using v1.8.518beta GPU

- Create L-Extreme stack in DSS

- Create separate L-Pro stack using L-Extreme stack as reference file but un-checked

In Compose module:

- Load L-Extreme stack in Luminance File slot; do I set exposure (9hrs) or leave to Not Set?

- Load L-Pro stack in each R G B File slots; do I set each RGB exposure (2hrs) or leave to Not Set?

- When creating my HOO Bi-Color, under Luminance, Color options, I normally select "L + Synthetic L From R(2xG)B, R(GB)(GB) (Bi-Color from OSC/DSLR)"; what do I select for this rendition?

Anything else I need to do or just click "Linear" and process as usual?

As a side note, does the new NBAccent module change things here with a different approach or the above is the way to go in this instance?

Thanks for the help!

Nick

Hi Nick,

my understanding is that using your suggested workflow you will get an LRGB image with the luminance coming from l-extreme and color coming from your L-Pro data. Do I understand correctly that you want an HOO or H(HO)O nebula with RGB stars? So you will probably be disappointed by the LRGB result since you can't do false colored images in an LRGB workflow. You won't get that Hubble palette style like in an H(HO)O rendition.

If you want to get your RGB stars into your HOO image you will have to process your L-Pro stack separately (with the exact same binning and cropping as for the l-extreme image so they are aligned perfectly). You can then load the l-extreme and the L-pro image into the Layer module with l-extreme as background. Create a good star mask on the l-extreme image and chose "color of fg" in the Blend parameter. Thus themasked l-extreme stars will get the L-Pro color.

The NBaccent module will give you lots of flexibility but it works differently. In Compose load L-Pro in Red, Green and Blue and the l-extreme stack in the NBaccent slot. You can then proceed as usual until after SuperStructure you get to the NBaccent module. Then you can try different settings and have a look what appears pleasing to you. There are lots of different possibilities.

Regards
Stefan

Hi Stefan,

Appreciate the quick response and you are indeed correct; I just tried the workflow I outlined and got a pretty "whacky" color scheme when jumping into the Color module; not at all what I intended.

I will try your suggestion next, processing each stack with same bin/crop and then combining in the Layer module; that was what I originally assumed I had to do but wondered if Compose offered another easier one-stop process flow; guess not in this case.

Its my first attempt trying to combine narrow-band with RGB so lots to learn. Let me see how it goes and will reach out with any issues.

In this case now, for the DSS staking, do I just create separate narrowband and RGB stack files without using a reference file from the other or still have to do that?

Cheers,
Nick

Hi Nick,

firebrand18 wrote: ↑Tue Oct 19, 2021 8:23 pm In this case now, for the DSS staking, do I just create separate narrowband and RGB stack files without using a reference file from the other or still have to do that?

You still have to do that so that the stacks are aligned and you have to bin/crop in the exactly same way for both images in order to keep the images aligned so you can layer them afterwards without offset.

Regards
Stefan

Ok, thanks. I will try it out and see how it goes.

Stefan, worked better than I expected! Did a quick default work flow on both stacks (same Bin/Crop) and got a Bi-Color HOO with really nice RGB stars! Completely changes the look of the narrow-band image (I traded in the L-Enhance for the L-Extreme filter a few months ago and love it).

Now to really work on processing both the Western and Eastern Veils in HOO-RGB stars blend; very exciting direction; more work of course!

Appreciate the guidance!

Hi Nick,

glad to hear it worked out for you! And yes, RGB stars give NB images a totally different appearance. I'm a huge fan of this workflow, too. It also doesn't cost much time. One or two hours with short exposures is enough for the RGB stars. You don't have to spend a whole night on it.

Regards
Stefan

Nick, by the way: Do you see halos around stars with the l-extreme? I read that people having used the l-enhance were not very happy with the new l-extreme because of this issue... Are you using a refractor or a reflector?

Agree, 1-2hrs in RGB is sufficient; I used L-Pro but may start using UV/IR filter instead to get more accurate color.

I was well aware of the halos with the L-Extreme before making the switch but with my quality optics on William Optics GT81 APO refractor with 0.8X flattener/reducer, pretty much the same halo effect on both filters and not really an issue for me. Obviously huge stars like Gamma Cygni become beach balls in processing but to be expected.

On another note, curious if you have tried buying an SII filter to use along with the L-Enhance/L-Extreme to create SHO composites with OSC (I have QHY 168C). Obviously not the same as a mono camera/filters but have seen varying commentary on CN and other sites that do this with good results.

Also, have you tried Siril for stacking? I am a DSS user from the beginning (with ST recommended settings) until two weeks ago got into comparing the two and find Siril is MUCH better with final image quality. With exact ST workflow on DSS and Siril stacks, produced less noise, sharper detail, better color and tighter stars in both narrowband and broadband targets; really impressed and will do more tests.

I ask as wondering how you would do the same process in Siril as in DSS in where you have to use a reference frame from the L-Extreme to stack the L-Pro data so everything is aligned later in ST to do the HOO/RGB blend we discussed.

Cheers.
Nick

firebrand18 wrote: ↑Wed Oct 20, 2021 1:29 pm I was well aware of the halos with the L-Extreme before making the switch but with my quality optics on William Optics GT81 APO refractor with 0.8X flattener/reducer, pretty much the same halo effect on both filters and not really an issue for me. Obviously huge stars like Gamma Cygni become beach balls in processing but to be expected.

Understood. I have a 150/750 newton. A quick search on Astrobin revealed that the 150/750 + l-extreme combo doesn't have huge halos. The l-extreme appears pretty attractive. Upgrading from l-enhance would have the advantage of getting rid of this pesky H-beta...

firebrand18 wrote: ↑Wed Oct 20, 2021 1:29 pm On another note, curious if you have tried buying an SII filter to use along with the L-Enhance/L-Extreme to create SHO composites with OSC (I have QHY 168C). Obviously not the same as a mono camera/filters but have seen varying commentary on CN and other sites that do this with good results.

I considered this but probably I won't make the step before I purchased a dedicated astronomy camera. At the moment I'm stuck with an old DSLR. It gives results which I am happy with but it has a bad QE (below 30%?). Going narrowband with a duo NB filter on a DSLR is fine for me since you collect photons on all channels, but with SII I would waste so much light due to low QE and single band pass. On top, SII is often the least intense source of photons. With a higher QE it would be a different matter...

firebrand18 wrote: ↑Wed Oct 20, 2021 1:29 pm Also, have you tried Siril for stacking? I am a DSS user from the beginning (with ST recommended settings) until two weeks ago got into comparing the two and find Siril is MUCH better with final image quality. With exact ST workflow on DSS and Siril stacks, produced less noise, sharper detail, better color and tighter stars in both narrowband and broadband targets; really impressed and will do more tests.

Have never used Siril but I made the same observation by switching from DSS to ASTAP. I'd add that by using DSS one looses faint details. I noticed especially with an image of the Pleiades. This was the disappointing DSS result: And this was ASTAP:
For sure processing wasn't 100% identical but you get the idea...

firebrand18 wrote: ↑Wed Oct 20, 2021 1:29 pm I ask as wondering how you would do the same process in Siril as in DSS in where you have to use a reference frame from the L-Extreme to stack the L-Pro data so everything is aligned later in ST to do the HOO/RGB blend we discussed.

I can't tell for Siril. In ASTAP you generate seperate stacks without referencing each other. But afterwards you align them using a dedicated part of the software giving you two new images which have added "aligned" to the respective file names. I know that @Carles uses Siril, maybe he can tell.

Regards
Stefan