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What am I doing wrong in DSS?


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Hi

A couple of nights ago I took 25 x 45" light frames of the Andromeda galaxy along with a couple of darks (my laptop battery, which runs my long exposure capture software, ran out!), 20 bias frames and 13 flats. By now my camera battery was also getting low so I cut down on the number of bias and flat frames.

I then processed the RAW files in DSS and got a third of a frame as a result - a quick look on SGL and I found out that for my camera - Canon 1100D - I needed to download the latest beta version of DSS.

This I have duly done and now I am getting this:

post-21511-0-90245700-1378409931_thumb.j

There is virtually no RGB information and no matter how much I stretch the image in photoshop I can't get any sort of result. If I stack the JPG files then I can get a reasonable image. Even though DSS isn't designed to stack JPG files!

Any help would be gratefully appreciated.

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Tried little stretches, but all I got was a few more stars appearing. I got absolutely nothing of the galaxy appearing, not even its bright centre. So I have given up trying to get anything and have resolved to get some more subs with a lot longer exposure times.

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Thanks for the suggestions and offer to have a tinker with my files, If I have still got the tiff file I will post it. I think I deleted all the files however to free up disk space. I will have a look the next chance I get.

James: equipment was a Canon 1100D with a Centon 500mm mirror lens. I think it is f8 - at work right now so can't check. This was mounted straight onto my CG-5 GT to keep the weight to a minimum. It did mean however that I had no way of doing a star alignment so that is why I kept the subs as short as I did.

I'm intending on using my Canon EF 70-210mm f4 zoom next time, set at around the 200mm mark and increasing the exposure to at least 2 mins. I have managed to set up a side-by-side system with my Travelscope 70 as a guide scope (using PHD), so hopefully I can now do star alignments and then attempt to do a drift alignment before I start imaging (never done one before - except on Peter Kennetts simulator programme on his Classic Astrophotography website). I am hoping to get the subs up to 5 mins if I can. Not sure what the light pollution is going to do with subs that long though!

Nigel: everything about this looked weird to me! :grin:

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  • 1 month later...

When you save your image after DSS has stacked the subs, you have to make sure you tick the box that says " embed but to not apply" if to apply the changes you will have lost a load of data and then get nothing from the image.

This is a common mistake made by people that are new to DSS.

Hope that helps

MM

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  • 2 weeks later...

Just curious, you say you took 25 x 45" and stacked, but DSS in your screenshot only said 1x 18 min exposure? Usually it sais total time, and number of frames. So seems like something have gone wrong somewhere. How many stars are detected whenb registering? you're posetive you selected light, dark, flat and bias properly (as in not mixing them up by misstake)?

Normally i'd say data is hidden in that peek, but i've very rarly seen dss give a stacked raw result like this. what stacking method/settings did you use btw?

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Can I join in here regarding DSS? Using the equipment in my signature, I cannot get more than a strip showing after I have stacked the frames.  I read another thread and downloaded the Beta file, again no joy. The star count is showing 0 for M42. I used 20x30" subs, tried using 4 darks. no flats or bias. I even tried a different computer as I thought maybe I don't have enough processing power - nothing different.

I have watched tutorials and checked everything out, but still no luck.  This is the first attempt at imaging so it's baby steps, but any help would be appreciated.

:smiley:

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Just curious, you say you took 25 x 45" and stacked, but DSS in your screenshot only said 1x 18 min exposure? Usually it sais total time, and number of frames. So seems like something have gone wrong somewhere. How many stars are detected whenb registering? you're posetive you selected light, dark, flat and bias properly (as in not mixing them up by misstake)?

Normally i'd say data is hidden in that peek, but i've very rarly seen dss give a stacked raw result like this. what stacking method/settings did you use btw?

I hadn't noticed that Jannis! That does look really weird? I normally adjust the star count so it is around 100 stars. I'm pretty sure that I selected the lights, darks, flats and bias frames correctly as I put them in different folders beforehand. The settings were the default ones - still learning so I don't like to change things that I am not sure about!

have u tried stacking just the light frames to see wot u get? maybe the darks,bias n flats r messing it up?

im not an expert just throwing stuff out there

I don't think I did try just the lights. It was so long ago now I can't remember. Mind you remembering what day of the week it is can be hard sometimes! :icon_scratch::grin:

I have just checked and I have deleted all my RAW files so it makes it all rather academic now! Thanks to everyone for their help and suggestions though. If I ever get outside and manage to get some imaging done, I will no doubt require your assistance again with the processing! :wink:

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As for stacking methods. I usually use these:

Average, if i have few subs.

kappa sigma-clipping (or median kappa sigma-clipping) when i have a high number of subs.

Using these 3 stacking methods, i've yet to have any serious issues with the stacked picture. With the other settings, i've had all sorts of odd issues, lilke no data at all, all black, all white, heavily clipped picture, and so on.

I'm not a pro in DSS, and it's still tons of settings i have no idea how to use properly - but for me at least, those 3 methods simply just "works", every time.

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