Compose and narrowband processing

[RICH-DSO]

I have made great progress with StarTools and processing narrowband data. Here is a few examples
https://www.astrobin.com/i35245/?nc=user

https://www.astrobin.com/pint8r/C/?nc=user

https://www.astrobin.com/y9md1g/B/?nc=user

When using Compose, if you are using H,S and O data into
The red, green and blue channels,

Question
1-should one turn- off the color interpolation button?
2- should the luminance,color option be rgb,rgb ? If no luminance is used?


Thank you for the answer.

[admin]

I have made great progress with StarTools and processing narrowband data. Here is a few examples
https://www.astrobin.com/i35245/?nc=user

https://www.astrobin.com/pint8r/C/?nc=user

https://www.astrobin.com/y9md1g/B/?nc=user

When using Compose, if you are using H,S and O data into
The red, green and blue channels,

Question
1-should one turn- off the color interpolation button?
2- should the luminance,color option be rgb,rgb ? If no luminance is used?


Thank you for the answer.

Apologies - I missed this one.
I think I already answered this via email, but I will answer here as well;

Answer to 1;
The interpolation is only performed if a channel is missing and it is needed for coloring. If all 3 color channels are populated, interpolation is not used.

Answer to 2;

If you are processing an SHO dataset, then load SHO as RGB (e.g. SII as red, Ha as green and O-III as blue). Set the 'Luminance, Color' parameter to 'L + Synthetic L from RGB, RGB'.
From here StarTools will process luminance (detail) and color separately, yet simultaneously. You will mostly work on the luminance (which is mono) until you hit the Color module.
As of 1.6 beta (highly recommended), you can select from a great number of popular color channel blend and channel remappings for your coloring by using the Matrix parameter (this assumes an initial SHO mapping).

So, all the above means that you

1. no longer need to process luminance and color separately and later combine the two

2. do not need to restart your processing if you want to remap your colors.

and

3. can still virtually use the same workflow for these complex composites as if they were simple DSLR datasets. There is very little difference.

In the tutorials section on the website, you can find two YouTube videos that use the Compose module.

[RICH-DSO]

Thank you Ivo for the information.

The Compose module works very well for narrow band imaging, saving me time. I find the processing to be more effective (less gradient and noise) than with osc images.
In DSS, I create my SII, H-a and OIII files, Open StarTools, click Compose and load the channels SII in Red, H-a in Green and OIII in the blue channel.
I crop the borders slightly for artifacts, and process as normal. I was not sure what the On/Off button was for, If all the channels are used, I now turn it off.

Got it.

Clear skies

[admin]

Thank you Ivo for the information.

The Compose module works very well for narrow band imaging, saving me time. I find the processing to be more effective (less gradient and noise) than with osc images.
In DSS, I create my SII, H-a and OIII files, Open StarTools, click Compose and load the channels SII in Red, H-a in Green and OIII in the blue channel.
I crop the borders slightly for artifacts, and process as normal. I was not sure what the On/Off button was for, If all the channels are used, I now turn it off.

Got it.

Clear skies

Narrowband imaging is great if you're imaging from light polluted skies. No light pollution domes (and associated gradients) and no light pollution noise component. It's looking more and more that this will be the future for many AP'ers, as LP creeps ever further outward from urban centers...

[happy-kat]

Acceptance of LP is not an option as it is also effecting insect populations (which we depend on) let alone our own health and that of other species.

[admin]

Acceptance of LP is not an option as it is also effecting insect populations (which we depend on) let alone our own health and that of other species.

Well said!

[happy-kat]

I am considering a tri band filter, though unless I dig out the barn door I am limited to 30 second images which may not be enough for such a filter.

[admin]

I am considering a tri band filter, though unless I dig out the barn door I am limited to 30 second images which may not be enough for such a filter.

Honestly, I've been rather impressed with the datasets I have seen so far. It doens't appear much ('important') signal is lost for objects that predominantly emit in the bands (e.g. HII areas) that the filter lets through any way. Of course, if you're going for wideband objects such as galaxies, you will start losing out on signal.
I'd definitely be interested in the results at 30s (but that's easy to say, as it's not my money )

[Lawrence]

I am considering a tri band filter, though unless I dig out the barn door I am limited to 30 second images which may not be enough for such a filter.

Honestly, I've been rather impressed with the datasets I have seen so far. It doens't appear much ('important') signal is lost for objects that predominantly emit in the bands (e.g. HII areas) that the filter lets through any way. Of course, if you're going for wideband objects such as galaxies, you will start losing out on signal.
I'd definitely be interested in the results at 30s (but that's easy to say, as it's not my money )

I don't know where your 30 sec time limit comes from but I am imaging at 5-min subs without problems. The guider is in front of the filter and therefore unaffected. My problem - see the query - is the colour result is all wrong and I cannot see how to fix it.

Lawrence Harris

[Lawrence]

Just to close my previous comment: as mentioned in an adjacent thread, My imaging for the time being - just to see how they all compare - is that I am using a quad-band filter in front of my M25C (rggb) Bayer colour matrix camera and guiding normally for 5-min subs. I could do 10-min subs but the probability of interference from planes-satellites etc increases so I limit them to 5-mins. The guide camera is in front of the filter with the AO system. I am also trying using a mounted guide-scope-camera but this has limits within the width of the dome shutters so AO use is much better. The filter was expensive (£170) but should enable me to image during high levels of moonlight. First tests have been very encouraging.

One query though: during early processing - wipe - there is a narrow-band option. Clicking help reminds us about wipe; there is no explanation of the significance of selecting narrow-band here. Should I be selecting NB here (because I am using a MB filter)? In addition, these options seem to be exclusive, not additive. Is that correct? One could have amp glow as well as make other selections.

Lawrence Harris