DeepSkyStacker - What is up with my stack?

[carastro]

This is the stack with just dark frames (no bias and no flats):

So it appears the problem is with the Flats and Bias.  So the next thing is to ask Chris how he does his flats and bias, what he saves them as and what settings he uses.  

Carole 

 

 

[carastro]

Now that's strange Adam that it all came out OK in APP, so maybe it is something weird going on with DSS.  Maybe time to ask the author of DSS what he thinks, or use a different stacking programme Chris.  

Carole 

[almcl]

I have had something similar happen a few times with the later version of DSS (I used 4.24 Beta 4 here) and it seems to be down to star selection.  I notice depsite raising the star threshold to 80% that DSS reports it is using over 4000 stars when doing the final 'align channels' so perhaps it is aligning on noise perhaps introduced by the bias or flat frames?

I wonder if @perdrix has an insight into this?

[RayD]

I'm loving this. It's like watching a murder mystery unfold 😀

Well done for your investigatory work @carastro and @tooth_dr, this is SGL at its very best 👍

[carastro]

Need a guru to work out what us actually going on though. 
 

carole

[Guest]

My apologies, I have been in back to back meetings all day - various iterations of Teams, Skype, Zoom and WebEx!

Humbled by all the help from everybody and wow how the drama is unfolding!

So lets cover the calibration frames. The frames are master TIFs instead of CR2 as they were once added as individuals but on prior stacks the masters were created by DSS. I have used all these masters before apart from flats which were taken after imaging last night - using my usual t-shirt, light source and the camera's Av mode. I have definitely used those dark and bias masters before a number of times though without issue.

I did uninstall DSS and delete settings and reinstall and rerun with different results - not correct results - just another type of wrong! Cannot even get the lights to stack now. The plot thickens.....

 

 

Edited July 17, 2020 by Guest

[Guest]

.... I do like silver linings and have to say after seeing your successful stacks, I am more than happy with my framing as this was the first time I did full framing using APT Plate solving and CdC  

[Guest]

I have uploaded the individual CR2 calibration frames that make up the calibration masters for those who are interested.

I did try stacking in ImagesPlus, the only other application I have used to stack deep sky up till now and that complained about different resolutions - all of the images are the same resolution!...

I have downloaded a trial version of APP which I will give a try. Any others highly recommended whilst I am looking at alternative options?

[Seelive]

So here's my stack of your lights + calibration frames (no processing, the TIF straight out of DSS).

This is with the stacking method set to Auto, quite an abstract work of art!:

And this is with the stacking set to Bilinear, still not good enough but a lot better.

As previously pointed out by carastro, the lights stack perfectly without the calibration files, but I've not have the chance to try each possible combination.  That's something I've also seen in the past but never got to the bottom of it - I'll leave that to you!

 

[carastro]

I would suggest a conversation with the author of DSS in the first instance.

This is the DSS Support Group and pretty sure the Author goes on there, if not there seem to be loads of people who can help. 

https://groups.io/g/DeepSkyStacker

Carole 

Edited July 17, 2020 by carastro

[geordie85]

I believe there is a problem with light leakage in your calibration frames, namely your flats.

Here is your master flat stretched

[Guest]

Thanks all for all the help and advice, it really is appreciated. The flats that night were rushed and I would be the first to admit that I probably did not use enough layers of t-shirt and a more dispersed light source.

Given APP managed the stack without issue I have switched. There appears to be a lot more options and it does appear to be able to deal with multiple mono filtered stacks a lot easier rather than doing them individually but with the same reference frame in DSS. I am not adverse to paying for software as well - DSS is a great starter considering it is free but I think APP is worth the investment.

[tooth_dr]

34 minutes ago, Chris Wright said:

Thanks all for all the help and advice, it really is appreciated. The flats that night were rushed and I would be the first to admit that I probably did not use enough layers of t-shirt and a more dispersed light source.

Given APP managed the stack without issue I have switched. There appears to be a lot more options and it does appear to be able to deal with multiple mono filtered stacks a lot easier rather than doing them individually but with the same reference frame in DSS. I am not adverse to paying for software as well - DSS is a great starter considering it is free but I think APP is worth the investment.

I agree, I was happy to pay for it as it really does a good job at stacking as well as making mosaics, and light pollution removal/gradient removal, and colour calibration.  I use it to combine data from two telescope/camera combinations.  I used DSS for a long time until it came unstuck for combining data at different sizes, then I switched to APP.  It can be hard to get onto it but worth the perservence.

[Guest]

39 minutes ago, tooth_dr said:

I agree, I was happy to pay for it as it really does a good job at stacking as well as making mosaics, and light pollution removal/gradient removal, and colour calibration.  I use it to combine data from two telescope/camera combinations.  I used DSS for a long time until it came unstuck for combining data at different sizes, then I switched to APP.  It can be hard to get onto it but worth the perservence.

Now there is another good reason! As well as my modded Canon 600D I also have an Altair Astro 183M pro with RGB+Ha+OIII filters and have data across both camera options for a few targets. I can start combining that data! Thank you very much for the heads-up!

[geordie85]

5 hours ago, Chris Wright said:

Now there is another good reason! As well as my modded Canon 600D I also have an Altair Astro 183M pro with RGB+Ha+OIII filters and have data across both camera options for a few targets. I can start combining that data! Thank you very much for the heads-up!

Yes it is very good at combining data. 

This is a mix from an atik 383L on a william optics star 71 (very widefield) and my qhy183m and William optics flt 98 (not very widefield).

App done this with minimal effort.