Help on LRGB+Ha image

[N_DD]

Hi,

I acquired a set of LRGB and Ha on NGC 6888 (Cocoon nebula). The total exposure is around 2 h for Ha and L, and 20 to 30 minutes for R, G, and B. Everything is calibrated with flats, darks and bias (I have acquired the data over two nights, and unfortunately I have rotated the camera in between...).
I tried to first process Ha separately, then LRGB and finally using the Layer module I added the processed Ha to the LRGB, but I am not sure if that is the best one could do... specifically, I have the feeling I cannot pull out the fainter regions of the nebula.

Can someone give it a try on my data? Here is the link

https://drive.google.com/drive/folders/ ... sp=sharing

More details:
L, Ha: 30 x 240 s (gain 150, T= 0 C)
R, G, B: 15 x 120 s (gain 150, T = 0 C)
QHY163M on C8 + FR (f=13000 mm) riding on an NEQ6, ZWO H-alpha filter (7 nm), ZWO LRGB filters, 30 flats for each filter, 30 darks for each exposure, 60 bias, stacked in DSS (median combining), processed with StarTools alpha 1.7

Thanks a lot!!!

Nico

[admin]

For incorporating HA, L and RGB into one composite to process, it typically doesn't take too much sense shooting deep Ha and L vs shallower RGB.
That's because blending Ha and L doesn't make a whole lot of sense for the purpose of synthetic luminance.You would either use Ha in your red channel, or use Ha by itself as luminance (e.g. not mixed with L).

Indeed you can also process Ha by itself and then add it to your red channel.

Easiest is to make a new red channel by blending Ha and R and import that as part of an LRGB composite (no further synthetic luminance generated).

Then process as usual;


--- Auto Develop
To see what we got.
--- Bin
Parameter [Scale] set to [scale 35.38% / +3.00 bits / +1.73x SNR improvement]
Image size is 1647 x 1246
--- Crop
Parameter [X1] set to [163 pixels]
Parameter [Y1] set to [172 pixels]
Parameter [X2] set to [1575 pixels (-72)]
Parameter [Y2] set to [1060 pixels (-186)]
Image size is 1412 x 888
--- Wipe
Vignetting preset.
Parameter [Dark Anomaly Filter] set to [5 pixels]
--- Auto Develop
Defaults.
--- Deconvolution
Parameter [Primary Radius] set to [1.9 pixels]
Parameter [Iterations] set to [33]
Parameter [Error Diffusion] set to [27 %]
--- Color
NOTE: Had to set LRGB Method Emulation to RGB Ratio, CIELab Luminance Retention due to the red channel being "weird/off" compared to the green and blue channels due to the new R channel we made.
Parameter [Style] set to [Artistic, Not Detail Aware]
Parameter [LRGB Method Emulation] set to [RGB Ratio, CIELab Luminance Retention]
Parameter [Dark Saturation] set to [3.0]
Parameter [Bright Saturation] set to [3.0]
Parameter [Saturation Amount] set to [146 %]
Parameter [Blue Bias Reduce] set to [1.46]
Parameter [Green Bias Reduce] set to [1.69]
Parameter [Cap Green] set to [100 %]
--- Shrink
(new 1.7 version)
Made a star mask that excludes the red channel during generation; this makes sure the mostly red nebulosity is not selected.
Parameter [Mode] set to [Tighten]
Parameter [Halo Extend] set to [1 pixels]
Parameter [Iterations] set to [10]
Parameter [Regularization] set to [0.85]
Parameter [De-ringing] set to [5 pixels]
Parameter [UNKNOWN] set to [1.5 pixels]
--- Life module
Isolate preset with 50% strength
--- Denoise 2 (swithced Tracking off)

Crescent.jpg (378.78 KiB) Viewed 2529 times

Many ways to do this, but no method will utilize the signal fully for the purpose of detail.

[N_DD]

...is THAT coming from my data?!?!


Thanks a lot!!! Actually I acquired luminance on the second night by mistake... made a note to myself to double-check the filter settings before shooting a sequence...

I am now trying to at least reproduce your great results. Did you use the layer module to blend Ha and R?

Thanks again,

Nico

[admin]

Good to know Nico.

You can indeed use the Layer module to blend Ha and R. Or you can use the Compose module ("Luminance, Color" set to "L + Synthetic Luminance, Mono" and then load the two channels in R, or G, or B which will effectively make a mono blend of whichever channels you import) and keep that result then save it.