SPCC with OSC and Filter

Stacey Baczkowski

When setting up equipment in the SPCC process, it is pretty clear what to do when using a OSC camera.  However, what do you select for filters when using a OSC with a filter (e.g., Opting L-Pro or IDAS NBZex?  Do you select a filter that has similar wavelength to the L-pro or IDAs or do you leave the default filters for a Sony sensor?

BlockHead

If it were me, I would find the transmission profiles for the light pollution filters and multiply them by the Sony filter. Then I would save this as the new filter profiles you should use. You would need to create a Red filter, Green Filter and Blue filter version of this custom thing. I suspect some one has already done this?

(The profile is here: https://www.optolong.com/cms/document/detail/id/13.html)

-the Blockhead

Jesus Bilbao

Would you please expand on this. 

I just got an Antlia Triband filter which I intend to use with my OSC, ZWOSI183MC Pro,, however I don't quite understand what options to use in creating the filter for this during SPCC.

Do I use the Narrowband filter option to input the bandpass information or can I create a filter for R,G &B similar to what I did for my Optolong L-Pro?. If so, do I use the Antlia V Pro Series options (only Antlia available) for each color together with the Sony Color filter ?.

Thanks in advance

BlockHead

Before we go down that road... 

Can you say why you want to use SPCC for this narrowband data in the first place?

Is there something about SPCC and narrowband processing you think is mandatory or desirable?

-the Blockhead

Jesus Bilbao

I was under the impression that SPCC was to be used on all data to obtain the correct colors. Being adjusted by the selected filters used. Wrong?.

BTW. I did now find the Antlia Triband option, poor searching on my part.

BlockHead

Yeah, I think there is something fundamental here that is not well understood.

When you use SPCC you can color calibrate your narrowband data and find the true line strengths. But then what? All nebulae are brighter in Ha compared to SII... And OIII can be weaker or brighter depending on the object. So does anyone abide by the calibrated line strengths? Not at all. The first thing people do is to boost the weaker signal and make a color image. So why do SPCC in the first place. What does it get you? If you wanted "correct" colors in terms of emission line strength... the Rosette Nebula is RED..really! It is red in broadband imagery...and taking narrowband data doesn't change that. It is red..the Ha dominates. 

So I claim you are not interested in obtaining "correct colors" at all.

Using SPCC isn't wrong...but I am saying it isn't aligned with your intended goals? Please let me know if I am way off base here.

-the Blockhead

Jesus Bilbao

I am too much of a beginner at this hobby to say one way or another whether you are or not. 

But since we are into the subject of colors. I guess one would start by asking, "what is the true color?". 

Then, why try to obtain anything other than the "true color". Why even attempt to use a Hubble Palette?.

And back to SPCC, what does it really accomplish?. 

The filters should allow the camera to receive the perdominant wavelengths outside of the light pollution, yes, no?. Once that is done, the question remains, "what else have you eliminated by doing so?".

Now, its probably me, due to my still ignorance in the hobby that might be off base !!. 

Your input and time is greatly appreciated. 

BlockHead

I would recommend watching my instructional videos on SPCC.

There is a distinction between color calibration (something you can do for both broadband and narrowband) and a white reference color balance (which is only broadband). 

So SPCC is removing any instrumental bias/issues of your system. You do not want you data to be whatever color just because of the instrument. This is particularly important for broadband images because the ratio of brightnesses in each color determine signal strengths which then can be transformed to a white balance based for a chosen reference.

This second part is not necessary for NB. There is no "white balance." The Hubble Palette is an arbitrary choice of color mapping..and again I repeat... ZERO PEOPLE USE TRUE SIGNAL STRENGTH in their NB images. So for NB... we are not using the second part.... and no one is caring about the first part. This is really all about  NB and how the information is rendered.

-the Blockhead

Mark Mayer

This was a very helpful thread to follow.

I was under the impression that for a three channel (e.g SHO) narrow band filter data set, that I would get more accurate star colors  if I used the Narrow Band Filters mode, and checked Optimize for stars, processing a master extracted using SXT.

I'm not sure if this is true, but my results speak for themselves. After running SPCC in narrow band / stare mode I usually have to run SCNR and sometimes even the Correct Magenta Stars script, or in bad cases even manual color balance manipulations to get 'normal' looking stars. 

I think what I learned is that you cannot get accurate star colors for narrow band data using SPCC - which begs the question why are the Narrow Band Filters mode, Optimize for stars, options in SPCC to start with?

BlockHead

The only purpose for NB mode in SPCC is for the calibration of your data for purposes of astrophysical signal strengths in each filter. There are some people that want this capability for various reasons. But it is not the reason that the vast majority of people are interested in. Most people think this is doing something to help them create a better NB image where the images are adjusted (with respect to the nebulae). But this is false... it isn't doing what I think people think it is.

-the Blockhead