#1  
Old 28-07-2020, 04:49 PM
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Biggest stack in DSS

I am stacking near 1000 subs in Deep Sky Stacked.. 30 to 60 seconds..maybe some two minutes in there or 90 seconds I can't be bothered doing a tally or inspecting each sub for quality as one really should do... At first it said 15 hours but it did the Stack in four but now says 6 hours for Computing final image.
What I am doing is using data gathered earlier this year (Eagle Nebula) with what I gathered last year..I have no idea how long total exposure is in this current stack is but maybe between 10 and 15 hours for HA... probably 5 hours for each other channel ..I plan putting the green with O-11 and that sort of thing so maybe I will get near 30 hours .. fortunately I am using my desktop which although probably running it all night with the genny leaves the lap top free cause the sky seems as if it will be clear...no I wont be getting more Eagle data ..in fact I cant think what to image as I had not planned on anything tonight...So what is the biggest stack you have put thru?
Alex
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Old 28-07-2020, 05:10 PM
Startrek (Martin)
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Alex
1000 subs must be a world record !!
I captured M8 Lagoon from Sydney in June and stacked 240 x 90sec subs which from memory is the most I’ve ever stacked in DSS
At my weekender ( dark skies ) I’m pushing 3 to 5 minute subs so I’m only usually stacking 25 to 60 subs max
First time I’ve heard stacking could take longer than post processing !!
Martin
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  #3  
Old 28-07-2020, 08:07 PM
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I am only 3 hours away.
It will be interesting to see how it turns out.
I am out there playing with the guiding but gone back to unguided to get something..it was going ok but still needs more..it's not bad but I had to come in and warm up so I turned off PHD and just am letting it run unguided ..Will warm up and play with it some more...it's saw tooth and I would like better before I use it...funny during tests it worked great and I have no idea why it plays up when I want to use it..lots of fun in any event..better sort it up if I move up to 3000 mm FL...back to 16 inch today...
Alex
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Old 28-07-2020, 11:21 PM
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Unbelievable..30 minutes off completion and while powering down the gear inadvertently switched off the inverter running the desk top, ...so filled the genny and starting again.
Did a ten minute test with PHD and went well signs of periodic error but really very good.
Two big days ahead and looks like it will be clear so sleep on Friday.
Alex
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Old 29-07-2020, 12:24 AM
raymo
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There was a guy on IIS about 8 or so years ago who produced terrific images
with his DSLR doing huge stacks of 30sec subs. His norm was 3 or 4 hundred,
but I suspect he did a lot more sometimes. If by chance he sees this maybe he can tell us. Anyway, I'm sure someone has tried more than 1000.
raymo
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Old 29-07-2020, 07:58 AM
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I didn't notice but my saved file list only had 700 and that finished this morning...too it to Startools and when I wiped it got only a black screen..so went with no wipe..lots of noise probably from some test shots U forgot to remove at 600 GA n..but the final prior to noise removal had hundreds of hot pixels and really over the top noise..Startools did a great job but it's back to the drawing board...
Alex
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Old 29-07-2020, 08:53 AM
JA
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Hi Alex,

Nowhere near the 1000 exposures you're going for, but I have done a couple of 100 plus runs in Sequator to get a feel for the improvements possible with reduced noise/colour mottle with increased number of subexposures. Definetly worthwhile.

Best
JA
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Old 29-07-2020, 10:13 AM
jahnpahwa (JP)
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I've done a few "many hundred" stacks, but probably not over 500 or 600, I reckon. These are very short subs on a static mount with my daughter. The file sizes should be similar, though.

I was going to ask/check that you register and stack separately? This breaks up the process, and once registered, that work is done and locked in, so if the stack fails then you're not back at square one.

I'm doing this on mains power, and I take my hat off to you and your set up there off grid!

JP
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Old 30-07-2020, 06:05 PM
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Quote:
Originally Posted by jahnpahwa View Post
I've done a few "many hundred" stacks, but probably not over 500 or 600, I reckon. These are very short subs on a static mount with my daughter. The file sizes should be similar, though.

I was going to ask/check that you register and stack separately? This breaks up the process, and once registered, that work is done and locked in, so if the stack fails then you're not back at square one.

I'm doing this on mains power, and I take my hat off to you and your set up there off grid!

JP
First I have given up on my big stack..it seems I was trying to stack data from the 80mm and the 115 mm...I could have sworn it was all 80mm but no..given the saying that you learn by your mistakes the day must come where I will by somewhat expert.

There is a better way ...but I do a stack of my first set of data and select a reference frame ..always the one at the top..and save that group as a "file list". Before I load the next data group I remove all but the reference frame then add the new data..if things crash I have the file list to grab the reference frame.

Also in StarTools I load, crop and save so I start with everything cropped cause if you crash you lose your crop reference..learnt that the hard way..last image of seven groups, crash, start again.

What I need to do is tell DSS to use less stars..at the moment I am registering a batch that has it counting up to 50,000 which makes it slow as.

And I give it a separate external drive so I don't get told not enough space.

It can be fun stacking during the night and wake up and notice the batteries need a charge ...so I go out fill the genny and start it up so the inverter won't protest and shut down.
Alex
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Old 30-07-2020, 06:38 PM
raymo
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Alex, if you remove the last three zeros you have a good number of stars.
raymo
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Old 30-07-2020, 07:08 PM
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How do I do that Raymo? There is something in there about star count I think and setting it lower but I just can't remember..it's ticking away at the moment so I can't look.
Alex
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Old 30-07-2020, 07:55 PM
Startrek (Martin)
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Alex
If your interested reading it , here’s my DSS stacking procedure ( including Star detection threshold) to produce your linear stacked fits file ready for loading into Startools

Deep Sky Stacker basic procedures

Open Deep Sky Stacker

All tasks and settings are on the LHS column

“Open pictures files” and load your Raw (Cr) files or Fits files
Open “dark files” and load your darks
Open “flat files” and load your flats
Open “offset/bias files” and load them

Press Check all ( all files will be ticked or checked in the file list at the bottom ready for registering

Press “Register checked pictures”

Register Settings box opens up
“Actions tab”
Tick box - already registered picture
Tick box - Automatic detection of hot pixels
Tick box - Stack after registering
Select the best 90% to 95% pictures and then “untuck this box” so you can check your Stacking Settings later ( I prefer to check later )
“Advanced tab”- star detection threshold try 10% at first but try other settings like 30% or 50% as there may not be enough stars for DSS to align
I recommend between 120 to 250 stars , so increase or decrease the star detection threshold to achieve enough stars

Recommended Settings button
DSS give you the recommended setting highlighted in green based on the number and type of files to stack
Stacking Parameters button
Intermediate files
Only check FITS files box and Use all available processors box
Leave other check boxes clear or unchecked
Press OK then DSS will start registering files

After files are registered press “Stack checked pictures”
Stacking Steps box appears
Recommended Settings button
DSS gives you the recommended setting for stacking highlighted in green ( you can change them if you want to )
Stacking Parameters
Result tab - check Standard mode
Light tab - check Kappa Sigma clipping
Alignment tab - check Automatic
Intermediate Files tab - check FITS files
Cosmetic tab - don’t do anything
Output tab - check Create Output file, check Append a number to avoid file overwrite, check Create Output file in the folder of the reference frame
Check Use available processors
Press OK
Now Press OK in Stacking Steps
DSS will now stack files based on selected settings

After stacking, DSS will create an output image ready to save
“Important” - do not use DSS RGB level adjustments , leave stacked image as it is

After stacking, in “Processing section” click “Save picture to file” option
Save as window appears , select where you want it saved in your computer and file name etc
Save as type will be FITS image ( 32bit integer )
Under “Compression” below leave as none
Under “Options” below , bullet check - do not apply adjustments to the saved image

Click save and stacked file should be saved to your file location ready for Startools or other processing software

Cheers
Martin
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Old 30-07-2020, 08:03 PM
raymo
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Hi Alex, Obviously the more stars you include, the slower the operation will be, so after ticking half a dozen frames, go into'Register Settings' and select
advanced tab at the top of the little window. You will see a slider. If for example it is set at 95%, and you need to reduce the number of stars, just slide it to the left down to say 75% and press the 'Compute number of detected stars' tab below the slider, and you will be shortly shown the number
of stars detected. About 50 is usually pretty good, so if the computed number
is still too high, just move the slider further left and compute again; repeat
the process until you're happy with the number.
Tick all your frames and register them. When all are registered, they will each have a score. Your good frames will all have similar scores, but some will have significantly lower scores.[ say 25% lower]. Go through the whole stack and untick the frames with poor scores, so they don't reduce the quality of your final image. And of course look out for meteors and satellites. Hope this helps.
raymo
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Old 31-07-2020, 03:32 AM
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Thank you Martin I am getting a collection of your most useful notes.Thank you Raymo I will give it a go when I get back.
Alex
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Old 07-08-2020, 04:18 PM
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A less ambitious stack this time for a new Fighting Dragon stack. The last was not big cause I was doing 3x drizzle and greatly limited how I did things from a numbers point of view..so luminance registration before applying Raymos advice said 4hours plus after after using Raymos guidelines it registered in about 10 minutes..I went outside and it was over before I got back so I am guessing but much better than four hours at most 15 minutes ..Anyways there are 312 (60 second subs) stacking now for L with about an hour to go with maybe another 300 subs for the rest..so 600minutes approx f I had my calculator I could tell you how many hours but it must be close to ten hours ..just L S H O
..just playing with the LRGB in StarTools...been raining all day.
Alex
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