M16 -- first try at a NarrowBand image

[BABOafrica]

I have some ZWO 7nm NB filters. I am using them for the first time with my QHY163m -- also still quite new to me.

I have only rough ideas about how to do this -- just enough to know I needed to get flats for each filter and that kind of stuff.

I used DSS, StarNet & StarTools v1.4 to process it.

It was supposed to SHO. So I loaded the S2 file at red, O3 as blue and Ha as green and then repeated Ha as the Lum.

I used StarNet to get rid of the stars after an initial stretch in StarTools and used StarTools to process the starless image. Then added the stars afterwards.

Processing was problematic mainly because the colors were nothing close to what I was expecting. The S2 signal does not seem to have made any difference. I played around with masks and colors for quite a long time. I had little idea of how to get better color.

Anyway, here it is:

M16 -- WO66 with 0.63 FR / AVX / QHY163m (SharpCap) / Guiding with Orion SSAG & PHD2

Ha -- 36 x 120s light frames
O3 -- 11 x 300s light frames
S2 -- 15 x 300s light frames

BABO

PS I am also working with a handicap of using a 0.63 focal reducer that was designed for a C8 SCT. Not the best combination. But it's the only way I can bring the WO66 to focus with the QHY163m. I eventually have to get some extension tubes. Maybe by Christmas...

[carastro]

Hi Babo, yes doing NB for the first time is a bit different to RGB.

Sounds like you did everything right though.

I don't use star tools, but I guess the principal would still be the same. I've attached a video I did of processing the Hubble palette in photoshop, there might be some info that would help.



Carole

[KathyNS]

A very respectable first effort, Babo!

Part of the challenge of narrowband is balancing the different bands. I haven't tried with Sii yet: my images are just Ha and Oiii. The levels are wildly different, so one band tends to dominate over the other(s). I found that Oiii tends to be much fainter than Ha, so I was taking 15-minute subs in Oiii, compared to 10-minute subs in Ha, and still I had to do some extreme stretching. Now, I have started binning the Oiii, so it comes out much better balanced. I have no idea where Sii would fit in terms of levels, but it is likely pretty dim.

Because of the challenge of balancing the bands, I get each band looking good on its own as a monochrome image before attempting to combine them. This means combining them after stretching.

[messier 111]

nice work, thx .

[starfield]

You're going to love narrowband. For processing and mapping colors, the StarTools Compose module is super helpful. I'm not sure if it's available in V1.4 but is definitely worth the upgrade. With Compose you load each channel separately and then work thru your set using your standard Startools workflow. Difference happens in the color module. There, you select SHO as palette type. Then, you'll see a control labeled "Identity". This lets you play with a different color mapping and blends. There's quite a range of maps and blends to choose from. Like @KathyNS metioned, your HA signal is usually much stronger than OIII and SII. I find that SII is often the weakest but that depends on the target. Also, you'll find that OIII is pretty sensitive to moonlight so I try to grab OIII on the darkest nights I can get (lately getting any clear night has been a challenge).

Have fun. --Steve

[Gordon]

Congratulations BABO on having your image selected as todays TSS APOD!

app.php/article/7-30-2021-tss-astrophot ... of-the-day

[helicon]

Excellent image BABO. Thanks for sharing it and congrats on winning the APOD for today.

[Mac]

You're off to a great start BABO. Congrats on the APOD!

[Graeme1858]

Nice go at some narrowband Babo.

Congratulations on the APOD.

Regards

Graeme

[AstroBee]

Congrats Babo on the TSS APOD!

[Makuser]

Hello Babo. A superb M16 (Eagle Nebula) image in NB from you. And very nice nebulosity details in your capture. Now that you have splashed your toes into the water, jump in and keep up the great work. Thanks for sharing your work with us Babo, and congratulations on winning the TSS APOD Award today.

[carastro]

have no idea where Sii would fit in terms of levels, but it is likely pretty dim.

Depends on the target Kathy. Some targets have pretty equal Oiii and sii, others have more Sii than Oiii, and there are some (such as California nebula) where there is no oiii at all but bags of Sii.

Yes Ha does tend to be the dominant NB filter, and I also process the NB filters separately before combining.

Carole

[yobbo89]

congrats on the apod,some good detail in the outer regions, it needs some work but you took the leap and have the basic principles downpat ,enjoye the narrowband path : )

[umasscrew39]

Excellent, Babo!! I almost do NB exclusively these days due to LP in my area. You will enjoy it as it actually more flexibility then broadband imaging and allows more artistic freedom :-).

[Lowjiber]

Nice work Babo. Congratulations on the APOD.

Clear Skies