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widefield dss stacking issues


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wondering if someone could give me some help on stacking in DSS for widefield shots. I'm really at my wits end and havent ever had this problem before.

I took 50 x 30sec subs of andromeda last night and they look fairly good.

chucked them all in to DSS and they all scored very evenly and had all the right info registered and went ahead and stacked used DSSs recommended parameters.

final image? WHITE.

opened it in gimp and played with the sliders and there is absolutely nothing there.

tried restacking in DSS with different settings - kappa sigma, average, media etc etc etc - remove hot / cold pixels on and off - all the time just getting a white output and nothing is in there when adjusted with gimp.

here is an example of one of the subs (jpegd and resized for uploading) - can anyone suggest what i'm doing wrong or what DSS settings i should use, as I;ve never had this problem before with my other widefields - even when they come out orange from light pollution, i can still usually get something worthwhile out of them with levels and curves.

post-26554-0-38862100-1411819470_thumb.j

thanks for any help

Nick

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Is there some setting in DSS that's stretching the final image to white ? have you measured the pixels, are they all maxed out ?

Dave

measured the pixels?

no idea what that is i'm afriad - but i'm using my normal widefield setup - 50mm pentax SMC lens at F2.8, same as my other stuff which has given me stacked images like the one below - so completely confused.

is there any stretching button i dont know about that i may have accidentally clicked?

post-26554-0-09587400-1411833468_thumb.j

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Can you post a "white" one ?

Dave

suitably resized and Jpegd for posting on here.....

even removed automatical hot pixel detection etc nd just had it do a completely manual automatic stack and still getting the same issues

any help would be awesome.

post-26554-0-61195400-1411990832_thumb.j

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Hi

What camera and what version of dss are you using? Do you see an image in the dss output screen after stacking? What do you get if you stack just one image? Have you configured/changed where dss stores the output file?

Louise

its a samsung nx100 - which DSS 3.3.2 doesnt like the raw files for - so i convert them to TIF in samsung studio and then load in to DSS.

all exactly the same as Ive done for half a dozen other widefield sessions without issue. Individually the images are all fine when you click on them in dss, but once stacked its all white.

RGB/K levels

what freaks me out is the black line is perfectly straight from bottom left to top right... so it doesnt matter if you move the levels down - it just goes from white to grey to dark grey to black - nothing showing.

as a test I just restacked some older data from kielder in summer and it all worked fine.

arrrrrrrr

might have just realised what it might be. I got a 2" baader neodymium filter for my dob the other day and noticed it fit over the end of my 50mm prime and took these subs with that on it - reduced the horrid orange on all the subs beautifully - as you can see from the example sub i posted... But would that have screwed something that would prevent DSS stacking them?

think i might uninstall and reinstall and see what happens,

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Had a quick scan over your white image and all pixels are nearly maxed out, there appears to be a small amount of detail going from bottom right to top left, nothing usable though.

Haven't used DSS for a while so not familiar with it.

Can you post a few original subs on Dropbox or somewhere ? and I'll stack them in another program.

Dave 

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its a samsung nx100 - which DSS 3.3.2 doesnt like the raw files for - so i convert them to TIF in samsung studio and then load in to DSS.

all exactly the same as Ive done for half a dozen other widefield sessions without issue. Individually the images are all fine when you click on them in dss, but once stacked its all white.

RGB/K levels

what freaks me out is the black line is perfectly straight from bottom left to top right... so it doesnt matter if you move the levels down - it just goes from white to grey to dark grey to black - nothing showing.

as a test I just restacked some older data from kielder in summer and it all worked fine.

arrrrrrrr

might have just realised what it might be. I got a 2" baader neodymium filter for my dob the other day and noticed it fit over the end of my 50mm prime and took these subs with that on it - reduced the horrid orange on all the subs beautifully - as you can see from the example sub i posted... But would that have screwed something that would prevent DSS stacking them?

think i might uninstall and reinstall and see what happens,

Hi

No the lp filter wouldn't have that effect. It's probably something fundamental and obvious... As I say, try 'stacking' a single sub and see what happens.

Not sure whether this might help:http://www.iceinspace.com.au/forum/archive/index.php/t-109543.html

Also, you might as well download the latest version of dss - v3.3.4: http://deepskystacker.free.fr/english/download.htm

Also, can you make adjustments to the image in the output window?

Louise

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Had a quick scan over your white image and all pixels are nearly maxed out, there appears to be a small amount of detail going from bottom right to top left, nothing usable though.

Haven't used DSS for a while so not familiar with it.

Can you post a few original subs on Dropbox or somewhere ? and I'll stack them in another program.

Dave 

thanks Davey-t!!!

i've uploaded 10 of them to our google drive - https://drive.google.com/folderview?id=0B6SpNS9lQrmOQUgwdE9EWFZYZXM&usp=sharing&tid=0B6SpNS9lQrmOUy1OdUZ3cUFXd0k

if you could have a go and see what comes out I would appreciate it.

Nick

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Hi

I downloaded a couple of the tiffs too. DSS was able to stack only one of the two. That usually indicates a problem with the subs. It's probably because of the star trails... I had to increase the threshold to about 15% and use the median filter option. It did indeed output on the dss screen as nearly white but was able to adjust. As mentioned above, they are also very noisy and there is a gradient - maybe a streetlamp or other local light source. It maybe the reason for the noise unless you used a very high iso? I did a quick noise reduction.

Anyway, fwiw, here's the single 'stacked' sub as jpeg with a few quick adjustments:

post-33532-0-16928200-1412115653_thumb.j

Louise

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Many thanks guys,

I can only presume the light from my next door neighbour has leached in and ruined them, even with the baader neo filter in place. Was just quite hopeful as you can see a definite smudge where Andromeda is on each sub. Must also explain the noise as it's only shot at iso800.

On a good point, new version of DSS recognises Samsung SRAW files now, so don't have to convert them to tif files first anymore.

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  • 3 weeks later...

had another go at this whilst sat on a very long and boring voice conference and decided to do something different.

Looking at the histogram, it was was too high, possibly 2/3rd the way up. So i opened the subs in samsungRAW and moved the histogram down to 1/3rd by sliding the EV value down to -1.50

batch processed them all and chucked it in DSS and out popped an image!

quickly made one adjustment in levels in GIMP, slid the left slider up to the base of the histogram and moved the middle one down to 1.20 (saw that on some youtube vid somewhere) AND OUT POPPED A GALAXY!!!!!!!!!!

done nothing else to this image, havent added the darks or bias yet or done any proper adjustments in gimp with layers... but that will have to wait as I have proper work to do now.

post-26554-0-70545200-1413801411_thumb.j

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