First stack of M42 subs

[Gina]

I've just stacked 20 of 25 light subs of M42 in DSS. 2s exposures at ISO 1600. But a gert big black hole has appeared in the middle of it Anyone any idea what's gone wrong here?

[eddy]

Looks like something has been over saturated to me, look at the stars, they are the same, having black rings, i find this happens to me when i have the "light" end of the histogram sliders too high, try bringing it down a bit in DSS

[Anweniel]

Did you process at all or is this just bare stack?

[Gina]

Looks like something has been over saturated to me, look at the stars, they are the same, having black rings, i find this happens to me when i have the "light" end of the histogram sliders too high, try bringing it down a bit in DSS

Thank you You're right - went back to DSS and altered the sliders and put it right

Here's the result stretched, cropped and scaled in GIMP for posting here.

[Slim]

That's a cracker Gina. You must be really pleased with it.

[Cozzy]

Nice that Gina, some nice detail in there, I like the dark dust. :.)

[eddy]

Well done Gina Great job, hope you dont mind i patched out the 2 noise signalsn that were present there

[Chris]

Thats a great first M42 Gina:)

[RobH]

Cracking!!

You must be rather happy with that

Rob

[Gina]

Thank you all very much Yes, I am quite pleased with it I have to say Thanks for you repair work, Eddy - much better

[Frogpills]

Fantastic image. You've got some lovely colour and detail in there. Well done!

[Gina]

Thank you

[Anweniel]

Great shot Gina, with the dynamic range of this object you can probably add a lot to it with further data, certainly I think you could get away with dropping the ISO still further and eliminate a bit more noise.

That said the dark nebulous regions have come out prettty well so god going

[Hawklord]

Nice shot Gina and well framed.

[phodso]

Lovely shot Gina, keep going.

[terrym2002uk]

Gina,

Nice image.

What stacking parameters did you use. On the output options you can tick a box to output a txt and html config file for the stack so you know what you stacked it with.

Try using AHD debayer, and median sigma clipping and hot/cold pixel clean up. May get rid of those trailing hot pixels. They seems to snake about as I guess you were dithering your exposures which is a good thing.

[Gina]

Gina,

Nice image.

Thank you

What stacking parameters did you use. On the output options you can tick a box to output a txt and html config file for the stack so you know what you stacked it with.

Ah thank you - I'll look at that. I'm on a very steep learning curve

Try using AHD debayer, and median sigma clipping and hot/cold pixel clean up.

I'll look into that.

May get rid of those trailing hot pixels. They seems to snake about as I guess you were dithering your exposures which is a good thing.

What happened with those trails of hot pixels I'm not sure. I think that's before I set up guiding. Quite a mystery.

[terrym2002uk]

Thank you

Ah thank you - I'll look at that. I'm on a very steep learning curve

I'll look into that.

What happened with those trails of hot pixels I'm not sure. I think that's before I set up guiding. Quite a mystery.

If that's before you set up guiding, then its likely just drift due to being slightly off polar alignment. and that make's it an even better attempt in my book - a great unguided image

[Gina]

If that's before you set up guiding, then its likely just drift due to being slightly off polar alignment. and that make's it an even better attempt in my book - a great unguided image

Thank you I shall be doing a drift alignment next time we get clear enough skies.

I thought it was clear last night and spent several hours capturing subs - both M42 and M51, but I failed to notice some thin high cloud which only showed up after hours of processing in DSS. Here's M42 with 100 lights and 15 darks of which DSS chose 80 lights for stacking. After fiddling with the sliders in DSS I further adjusted the curves in GIMP. I think this could have been a good result had it not been for a stripy background from the cloud obscuring the fainter detail. I also did another 100 lights at lower exposure to get the stars in the centre part - I haven't processed these yet.

[Spikey]

Gina, that might not be enough darks and might have added quite a bit of noise. What does it look like stacked without darks?

[Gina]

Gina, that might not be enough darks and might have added quite a bit of noise. What does it look like stacked without darks?

I might give that a try though I don't think darks would make much difference with the short exposures used here.

[ncjunk]

Lovely image! Nice to see it all coming together :thumbup:

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[Gina]

Lovely image! Nice to see it all coming together :thumbup:

Thank you

Forgot to give the subs details - these were 100 subs of 10s at ISO 1600 plus 15 darks. I have another set of 100 subs of 5s at ISO 800 designed to bring out the light part which gets overexposed on longer exposures.

[Gina]

Ran DSS overnight on M42 on 199 light subs in two groups one 10s at ISO 1600 and the other 5s at ISO 800. No darks used. All 199 subs used in one go. DSS chose 159 to stack. After stacking I adjusted the sliders to give what seemed the best result to me. I then cropped in GIMP and uploaded to Photobucket. Here's the result - an improvement on previous stacks Some black level clipping has occurred somewhere - I might see if I can find where and put it right. These are still suffering from thin high level cloud. And the dreaded wiggly bits are back. Wonder if it tiny bits of fibre.

[Gina]

Adjusted sliders in DSS, fiddled with the curves in GIMP cropped and scaled. I don't think there's much more I can do with that data due to the cloud.