Any idea why my DSS output is all jumbled?

[VigdisVZ]

Hey guys

Just came in after an awesome first imaging session with my 6". I managd to capture some good 20 sec subs of M31, but when I stack them in DSS the output ends up like the attatched pics. The only difference is the the star-threshhold, that I tried altering, but nothing results in a clear image. THe subs look really good, so I have no idea why the program does this. Any help would greatly appreciated as I've been tearing my hair out the last hour.

[allcart]

very bizarre. Are all your subs the same orientation.? Can you post just one sub.

[VigdisVZ]

Here are a few of the subs in JPG, I'm stacking the .NEF raw Nikon frames.

It seems to read the raw fine, as the images are sharp and clear, but something happens during alignment...

Could it be that the micro vibrations from the shutter distorts the star shapes enough so it cant find its way?

Going to have a go with JPG's just to see if the .NEF is screwing with me...

Reporting back soon...

[allcart]

Also, check your alignment choice in the stacking parameters tab.

[Helen]

I'd say try changing the threshold to produce more stars for stacking and see what happens, it looks there is an alignment problem (whether that is the only problem remains to be tested).

Helen

[allcart]

I don't see anything wrong with those. Check all your stacking parameters after you have registered them. Make sure you have not selected 'don't align' by mistake.

[VigdisVZ]

I have tried atlest 4 different thresholds. Will try the alignment choice when the JPG frames finish cooking.

[allcart]

Good point Helen.

How many stars are you detecting in DSS.

[allcart]

You only need to register one frame to get access to the stacking Parameters menus.

[VigdisVZ]

I'm poking around inside the parameters menu now. Also not sure how many stars i should detect, I can get from 800+ to just a handful.

[VigdisVZ]

Ok one "out of memory" and one program crash later I have a non jumbled image.. now to bring out the details in it Thanks for the support all!

[Helen]

Result!

Helen

[allcart]

Don't forget to show us. For a 20sec sub they looked pretty good.

[VigdisVZ]

Thanks for cheering me on. Color balance is way off, but its a good result for the evening. Will revisit asap.

[dph1nm]

Also not sure how many stars i should detect, I can get from 800+ to just a handful.

You need at least 8 for DSS to work at all - but more than 20-30 is overkill in my opinion. DSS only fits linear shifts or rotation, it does not rescale, shear etc, so there is no point in having a lot of stars.

NigelM

[allcart]

Ok Carl, so its not perfect, but what a great first dso. well done.

[VigdisVZ]

Thank you for the encouragement. I revisited the image today, very happy with the result after having so little data to begin with.