Choosing the Correct PSF Algo for weighting

[BlueRidgeDSIA]

I think you are missing the point of HDRComposition and you are using it in the worst way possible here

When you said:


What do you mean? If you mean that you use the process HDRcomposition with the 300s, 600s and 900s stacks then it does not make sense in my opinion and you are indeed loosing data.

The aim of HDR is to improve your dynamic range, and for your M42 target the aim is to reveal the core of the nebula. To do that you need to compose stacks with a meaningful difference of exposure time. Typically a very short exposure time to deal with the core with a much longer exposure time to deal with the rest of the image. Your 300s, 600s and 900s will not change anything regarding M42's core and, when you combined them through HDRcomposition you are probably mostly keeping the information from the 900s stack and loosing everything else. Just look at the composition mask.


Then when you said :


What do you mean? Did you use HDRcomposition to combine the 2 stacks or something else?
If you use HDRcomposition you are saving the dynamic range but you are loosing data and if you are using another mean (Pixelmath or ImageIntegration) then you are loosing dynamic range.
This 2-step approach cannot be good

With your data here is what I would try:
Integrate all your exposure of 30s and more into one stack
Integrate your 115X10s files into another stack
Use HDRComposition to compose these 2 stacks.

With this approach I believe you'll have the best possible SNR for you image and you'll have information in the nebula's core

And for the next target I would try to avoid taking so many different exposure times and use maybe 2 or 3 different exposure times maximum for hight dynamic targets.

300s stacks repair clipping generated by 600s which then repairs clipping generated by 900s.
The value in the longer exposures was in exposing the faint background around orion at 342mm on my ASI2600mc under bortle 5 skies

10s-120s repaired Orions core.

Dynamic range was preserved in a somewhat holistic attempt, in the end I used HDR combination on the 2 masters to see if the noise levels improved, and they did slightly, but no where near as clean as the image that integrated every sub into 1 single image.

Ultimately the goal here was experimentation. I have imaged for over 10 years and am well aware of how to image and what exposures I should use. I am intentionally breaking "traditional" capture procedure. I really want to reduce the amount of data I need to stack in the future so I will continue shooting either 600 or 900s longer subs and spend at least 1/3 of the integration shooting shorter subs.

I want my 20hr plus projects to stop gobbling up 1tb and + of HD space and I want to avoid waiting 9 hours for data to integrate on a 16core processor.
I want a nice clean background and I want to preserve my star color.

 

[fredvanner]

Really the basic idea with HDRComposition is to take as many exposures as you want at the maximum exposure you intend to use, and then take as many exposures as required at the longest possible exposure that does not result in any saturated pixels. Any exposure times between these two will usually be redundant (that is, they will simply be discarded).

 

[pfile]

few objects are so bright that they really warrant lots of exposure lengths. M42, yeah. core of M31, maybe. a total solar eclipse, yeah. but beyond that, on most other targets, all you're doing with the shorter exposures is recovering the saturated star cores. and there's no real need to do so many shorter exposure lengths to capture that.