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Old 29-06-2011, 12:49 PM
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Stacking many subs of different sub times

Hi,
My question is with regard to my ongoing Rho project.

I have around 80 subs of varying exposure times to align+combine.
50x5mins, 40x 7.5mins and 10x10mins.

What is the best way to do this...

1. align/combine all subs together into 1 mixed up stack?

or...

2. align/combine groups of equal times then combine those 3 stacks into 1 file?

Cheers

Doug
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  #2  
Old 29-06-2011, 03:55 PM
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I'd throw them all into DSS and see what comes out.
I've done it before successfully.
Mind you though, the last time I tried it with Rho Ophu, for some reason it didn't work, and I was left with a real "what tha" image. LOL I'll post it up later if I can find it.
Be interested to hear others opinions on the topic.
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Old 29-06-2011, 04:15 PM
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renormalised (Carl)
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#2 is your best bet, Doug. At least you'll be getting some consistency in the stacks of subs and you won't have to mess about with weird combos of darks, flats etc, to get everything looking alright. That will also help your final image turn out good as well.

You could just throw everything into the pot and see what comes out. You never know, you might end up with a great piccie. Then again, you could end up with a dog's breakfast
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Old 29-06-2011, 04:23 PM
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Quote:
Originally Posted by renormalised View Post

You could just throw everything into the pot and see what comes out. You never know, you might end up with a great piccie. Then again, you could end up with a dog's breakfast
You never know if you don't give it a go. If it doesn't turn out, you can post it to show us what not to do. LOL
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Old 29-06-2011, 04:30 PM
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I am at this stage now, I recently tried a #1 dogs breakfast and it seemed to work.

The #2 option requires more processing combining skill which I sadly lack at this stage still haven't worked out layer masking only layer combining.
Tried to combine a DSS 30 second stack and DSS 1 minutes stack of exposures of Carina and came up with a dogs breakfast
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Old 29-06-2011, 04:30 PM
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I would do number 2 to as well Doug, at least it has some order to it, however I would also do the first mix, and then compare, if no difference you are wiser for next time.

Leon
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Old 29-06-2011, 05:15 PM
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Quote:
Originally Posted by jjjnettie View Post
I'd throw them all into DSS and see what comes out.
I've done it before successfully.
Mind you though, the last time I tried it with Rho Ophu, for some reason it didn't work, and I was left with a real "what tha" image. LOL I'll post it up later if I can find it.
Be interested to hear others opinions on the topic.
What do you do about darks of different exposure times to match your lights? Only time I tried that, DSS smacked me across the knuckles.
Peter
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Old 29-06-2011, 05:25 PM
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DSS sorted them out for me, and the time I didn't add the correct flats, it told me it couldn't use them.
The Dumbbell and The Helix were two objects I spent a month collecting data on. A half hour here, a half hour there.
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Old 29-06-2011, 05:28 PM
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Bottom line is it depends on your software and the settings you use. If you've got subs of differing lengths then you need master darks and master bias frames so the program (if it can) can calculate a "virtual master dark" for each exposure length.

The other problem is the longer subs will generally show lots more detail, so for faint fuzzies you're have to decide if there'll be any dilution in signal by including the shorter subs just to try and reduce noise. I'd suggest it will depend a lot on objects, variation in times, light pollution among other things.

(was that wishy washy enough!?...)
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Old 29-06-2011, 05:30 PM
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Just do it Doug, you know you want to......show us how it's done.
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Old 29-06-2011, 07:13 PM
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Let's just say for argument's sake that I'm not going to use darks or flats!!

LOL - thanks for the input all and the PM Rally.
I'm going to go for box No.2 and see how that pans out.
Cheers all
Doug

Last edited by dugnsuz; 29-06-2011 at 07:25 PM.
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Old 29-06-2011, 08:15 PM
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Quote:
Originally Posted by pmrid View Post
What do you do about darks of different exposure times to match your lights? Only time I tried that, DSS smacked me across the knuckles.
Peter
Peter: Maxim will match and scale your darks (you need bias frames as well) to the exposure times for the light frames. Dunno about other software, but I expect you can do this in some other packages as well.

Wrt to the original question, I have started to play around with HDR in PixInsight using option #2 and so far my experiences have been positive.

Cheers,
Rick.
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Old 01-07-2011, 11:17 PM
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Results...
Stacked 'like' subs then combined the resulting stacks into one.
Struggled with light pollution too - prompted me to purchase a new light pollution filter!

High Res...
http://s327.photobucket.com/albums/k...urrent=21c.jpg

Cheers
Doug
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Old 02-07-2011, 12:44 AM
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OH wow Doug, that's just gorgeous!!!!
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Old 02-07-2011, 07:32 AM
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Can't you take a hint, LOL, do it "Netties Way" or else, LOL
Looks good like you got though Doug.
Gary
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Old 02-07-2011, 07:48 AM
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Got to be pretty happy with that Doug, I like it.

Leon
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Old 04-07-2011, 10:52 AM
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Nice
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Old 04-07-2011, 12:17 PM
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I would do the reductions on all subs and then throw the lot in....scaling isn't always perfect but nothing ever is anyway i guess.

Very rich in color Doug....nice! looks to me like you could be more aggressive with your stretching IF you wanted too.
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Old 05-07-2011, 09:32 AM
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Quote:
Originally Posted by atalas View Post
I would do the reductions on all subs and then throw the lot in....scaling isn't always perfect but nothing ever is anyway i guess.

Very rich in color Doug....nice! looks to me like you could be more aggressive with your stretching IF you wanted too.
Thanks for the advice Louie.
Stretched more aggressively...
http://s327.photobucket.com/albums/k...urrent=21d.jpg
Doug
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Old 05-07-2011, 06:01 PM
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Now that Repro is looking really marvelous!!

Well done. I am struggling with mine at the moment as when I stretch, it's starting to wash out down near the bottom as the field approaches the denser area of the Milky Way. But I;m using my 50mm at the moment.

This has been a very interesting thread!!

Darrin...
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