Deep Sky Stacker and post stack processing

[sbj]

Evening all,

Have attached my third attempt at AP.  Orion Nebula, just 6 exposures stacked with DSS with bias frames, darks and flats should as per DSS instructions.

The final output image has a lot ( to me) of detail but appears very light.  Is this simply a result of how bright it was last night?

When I output the image to PS Elements 10, the image becomes a little darker in the transition between the programmes.

When I adjust the lighting in elements, I then seem to lose a little of the overall detail.

Any input and advice appreciated.

DSS output

image when "transferred"

[Astrosurf]

That's a good start. Looks like you got good focus. The Moon washes out the sky to the point you can lose detail in deep sky imaging. I tried out the Bubble Neb with a bright moon last Thursday and it had less detail with 20-odd stacked subs than it did with the 2 subs I managed to get a few days before when it was dark! And the exposures were shorter too in those.

DSS output is always dark. I use Levels to start stretching the image in small iterations. Then I use Curves to increase contrast. Then I alternate, sort of. Do this very carefully. I also do other things to stop stars and other bright areas getting blown out (particularly as the Orion Neb has a high dynamic range) but that's a bit complicated to put here! Just have a go at Levels and Curves first. There are lots of tutorials on the Web.

Alexxx

[frugal]

DSS is probably doing a stretch on the data when it shows it to you. If you look at the area below the image, to the left of the RGB sliders you will see the stretch it has performed. My copy of DSS defaults to "log (sqrt)". If yo7 change that to Linear you will see the data as it is actually stored, which should be really dark.

I had not realised until watching some of Harry's PixInsight tutorials that the human eye has a non-linear response curve. So when the human eye looks at the stars our eyes are more sensitive to the dark stuff. The camera records the data linearly, so when it is shown in Lightroom, or even Canon DPP, the software has already done a stretch on the data before showing it to you.

Part of processing the dark file from dSS is to do the exact stretch that you want for the data rather than having Lightroom make the assumptions for you.

Sent from my GT-N7000 using Tapatalk

[PorkyB]

I did a quick and nasty process of your pic with GIMP and got this...

... a bit over-stretched maybe, but still a very nice pic I think.  Nice detail in the heart of the nebula.

Did you make any adjustments in DSS? I find it better to save from DSS without altering anything, and then just do levels and curves in GIMP.

[sbj]

Had a little play with levels etc and got to this: