Deep Sky Stacker only wants to stack 1 frame

[RobertB]

I'm having real problems with DSS.

I'm trying to stack some images taken with a Canon DSLR but no matter what I do it tells me only one frame will be stacked and I should check/change star detection treshold and find a transformation between the reference frame and others.

I have adjusted the star detection treshold so it finds approx 20 stars - I have no idea how to find a transformation between the frames though!

I have this problem no matter what the image is of, how many frames I'm stacking or what format the frames are in. Whether I'm stacking some frames of an open cluster taken through the scope or just a couple of shots of Orion, it only wants to let me stack one frame.

Oh, and even if I do let it "stack" one frame the result is terrible!

I have gone through the DSS user manual, as well as searched for online guides and tutorials and followed them to the letter, but nothing sees to work!!!

Help!!!

[jgs001]

Hmm.. do you have an example of one of the images you're trying to stack ? Also, what level do you have the star detection threshold on ?

[Mark-mck]

hi Robert.

i have this problem from time to time and its always down to focus, so i always take a few subs and check in dss to see if i've focused properly before i take a load of subs, and yes i have taken about 200 subs all out of focus before now lol.

hope that helps,

Mark

[martin_h]

Try the threshold on its lowest setting - 2% ?

If it wont stack them then it must be dodgy subs- focus, trailing?

[RobertB]

Hi All,

Thanks for the replies. I have tried it with the threshold being set to just 2 or 3% and although it found hundreds (actually thousands on 2%) of stars it still would not stack.

Must admit the focus/trailing is likely to be the culprit by the seem of things. The stars looked ok at a casual glance (and seemed fine on the DSLR screen - it wasn't contected to my laptop when I took the shots) but looking closer they aren't perfectly round but definately trailed.

I'll try again next time it's clear (not holding my breath on that one!) and spend some more time getting the focus tighter and perhaps try shorter exposures to limit trailing too. Once I then at least get it stacking I can start pushing the boundaries back then!

If it doesn't work then, then I guess I should focus on planetary imaging - at least me and Registax get on well!

[Black Knight]

I used to get this problem. It generally is down to focus/trailing.

For trailing, you need to ensure you have the best polar alignment you can get and make sure your sub length isn't too long. In the end, I could only manage 60 second subs even after drift aligning. More routinely I could get 30 second subs reasonably successfully.

For focusing, I slew the mount to a bright star (at the moment something like Rigel, Aldebaran, Capella etc) and use the zoom function in the cameras Live View to try and get the tightest star I can. Once that is done I slew to my target, frame it up, and click away - so to speak. Things are a bit easier now I am experimenting with guiding.

Since you are using a Canon DSLR have you tried Ivo's APT to manage the exposures (http://www.ideiki.com/astro/)? With APT you can preview each image after it has taken and you can see if the star field moves or rotates slightly after each image. If so, try tghtening up your polar alignment, perhaps using drift alignment as well. I don;t have an illuminated reticule eyepiece so I use WCS to help with drift alignment. It's not without its faults, but it will work with a webcam if you have one. You can get WCS here: Polar Alignment - WCS - Fast and accurate polaralignment for astronomical mounts, using a CCD / webcam and drift alignment. There is an evaluation period of around 30 days before you have to register for this program.

Hope this helps,

[dph1nm]

Thanks for the replies. I have tried it with the threshold being set to just 2 or 3% and although it found hundreds (actually thousands on 2%) of stars it still would not stack.

These aren't stars - they will be noise, and will certainly prevent DSS from finding alignment.

You need to make sure the stars it has found at more sensible setting are real (you said it found ~20 I think - BTW, you need at least 8 for stacking to work). Use the star editor in DSS for this. This will show you which objects it thinks are stars - check that those 20 really are! If not, you can edit them out by clicking with the mouse.

NigelM

[RobertB]

Thanks for the further advice - I've decided to put this on hold until I can get some better quality images when the clouds next part. Won't try to go for anything amazing, just some short subs with no trailing and good focus, just to get things going.

Thanks for pointing out the minimum, and also about the Star Editor. That's a feature that I noticed but didn't know what it was for or how it worked.

Also thanks for the links!

Fingers crossed for some clear skies over the weekend.

[Jannis]

upload a sample pic, and we'll have a look. in many cases you can fool DSS to accept it by simply making the pic a tiny bit smaller.

[RobertB]

Just to let everyone know I have managed to get DSS to work.

Over the weekend I managed to take some widefield shots of Orion and Hyades using a tri-pod mounted DSLR. I kept the exposures short and had quite a high ISO setting. Having a full moon glaring away didn't help matter too much!

I spent some extra time on the focus and set the camera to take 5 consecutive shots (then fiddled with focus and settings and tried again, to cover various options).

I have managed get plenty of alignment stars with a reletively high threshold and it stacked fine. The image I immediately saw looked dissappointing but I opened the TIFF in Photoshop and tweaked the levels with a ham-fisted approach and suddenly the detail jumped out.

The images aren't anything amazing (and as I said, the full moon didn't help) but at least I have learnt something I didn't know previously and at least know I can get the software to work!

[RobertB]

Oh, and forgot to say in the last post; thank you to everyone who helped.

[frewi808]

This is my picture and deep sky stacker can't find any stars !?!?!? I adjusted the threshold a few times but no result !

[Carina Lass]

Comet lovejoy eh?

I guess its overwhelmed the analyser.

the stars and lovejoy move at different rates.

Very difficult in dss Try registax

[happy-kat]

Did you use the feature that you use to mark the centre of the comet on each light in dss?

[happylimpet]

I'd stack that in AutoStakkert! It worked for me before with a bright comet.

If not, threshold down to 2% and tick median filter (or you detect lots of hot/warm pixels).

[frewi808]

Thanks that really helped a lot !!!

[MarkWW]

I've used DSS once, successfully. Now the second time I try, it won't recognise stars.  The first file DSC01434 is the first of 37 images taken with a Sony RX100 M3 - 2 minute exposures at ISO400 F-2.8.  No problems with focus or trailing as far as I can see. The word document is a screen shot of what DSS is trying to process. As you can see DSS isn't uploading the image correctly hence the inability to process. Any suggestions on how to overcome this issue would be much appreciated.

DSC01434.ARW

DSS Image Problem.docx

[happy-kat]

Make sure using DSS 3.3.4. 

[PeterCPC]

or 3.3.6

Peter

[MarkWW]

3.3.4 Did the job. Thanks