Two colour variations of NGC6888

[admin]

If they claim they are visual spectrum images, without any Ha accenting, then yes, those would be inaccurate color/emission representations.

EDIT: I should however mention that some regions are very dusty as well, and tend to filter out blue light. A good example is the horse head nebula region, which appears quite a bit redder.

[Mike in Rancho]

Ok Ivo, thanks for your explanation.

However this means then that actually most pictures we see of the eg Heart nebulae on the internet are just inacurate. Many of them are just red not pink.

I imagine it depends on the acquisition and composition. Many Heart and/or Soul don't even include RGB, unless maybe for stars. And for false color narrowband, you could make the Ha green and it would still be perfectly accurate.

As for being pink, I suppose it depends what you mean. If Ha is used as luminance, red colors can be warped into pink. Extremely common with old school HaRGB. That's a known disconnect between L and Color and I believe discussed by Ivo in many threads. But I think the NBA module in ST lets us remedy that somewhat?

Inclusion of the other Balmer lines, which would be variable if even there (dependent on temperature I think?), if anything would take the red in a purple direction rather than pink.

EDIT: Oops, didn't see this went to a second page and Ivo answered already.
Though I still thought Balmer went more to purple than pink...

[fmeireso]

Hmmm, all this made me tinkering. Maybe i could be better off taking color with my L-enhance filter on , like i did a couple of times....Since the L-enhance afaik lets through OIII, cyan blue and Ha 656 Nm red i could have perhaps nicer red/blue coloring. Off course bye bye star color then..... or i take a third session , plain OSC just for star color and somehow blend it via the layer module. Trouble is then i need allready 3 sessions /object.

[Mike in Rancho]

Hmmm, all this made me tinkering. Maybe i could be better off taking color with my L-enhance filter on , like i did a couple of times....Since the L-enhance afaik lets through OIII, cyan blue and Ha 656 Nm red i could have perhaps nicer red/blue coloring. Off course bye bye star color then..... or i take a third session , plain OSC just for star color and somehow blend it via the layer module. Trouble is then i need allready 3 sessions /object.

Well plenty of ways to combine things I suppose. Separate RGB stars is a common late modification if the base image is otherwise narrowband.

What exactly is the goal you are after? Close to "accurate" as to human eye perception? As to luminance? Color? Both? Plenty of caveats involved with all that.

Is this for the Heart data in your separate thread? Maybe in there you could link the stacks (though you said maybe a calibration error in PI?) and we could try some combinations to see if they end up more towards your plan.

[fmeireso]

No Mike, for the Heart nebulae i am pretty satified with the outcome. The ideal is ,for future objects, to get a red Ha emission nebuale, not a pinkish one, and to get as much nebulosity as possible, well without overstretching it either off course.
I have yet to determine what would be the best way to pursuit this.

I will add my links to the stacks in my Heart red or pink thread if you want to have a got at it.

[fmeireso]

Is this for the Heart data in your separate thread? Maybe in there you could link the stacks (though you said maybe a calibration error in PI?) and we could try some combinations to see if they end up more towards your plan.

Done