Back to forums

How to stack images with very few stars?

Luc Coiffier DeepSkyStacker (DSS) Processing Stacking Deep Sky Planetary Nebula
9 replies•627 views
Abhijit Juvekar avatar
Abhijit Juvekar avatar
Hi,

I use DSS for stacking.
Sometimes while using short exposures, particularly for imaging Planetary nebulae I find the DSS don't register more than 2 stars and hence don't stack more than 1 frame despite having the lowest star detection 2% setting.

In such case end up with only single frame stack which is pointless.

What other program is there to stack images with very few stars in it?

Thanks!
dkamen avatar
dkamen avatar
Hi,

I guess you can try treating them as planetary imaging. Siril has an algorithm for that. PlanetarySystemStacker and every other planetary stacking software also, but you might have to convert your images to SER video.

Alternatively you can do manual registration on PixInsight (or play with the automatic registration settings to find something that works, generally speaking this is quite likely).

Cheers,

Dimitris
Helpful
kuechlew avatar
kuechlew avatar
I gave up on DSS a while ago when it had occasional trouble stacking my field-rotated images with AZ GTI in Alt/AZ mode and switched to PixInsight. Admittedly when it works it's one of the fastest stacking programs out there.

You may try to play around with the star detection threshold in DSS:
DeepSkyStacker for Astrophotography | Beginner-Friendly Tutorial (astrobackyard.com)
That detection threshold seems too high: Astrophotography Talk Forum Forum: Digital Photography Review (dpreview.com)

Clear skies
Wolfgang
Helpful
Robert Winslow avatar
Robert Winslow avatar
Siril, can stack and you can tell it to do one star or 3 star registration.  It works well for that, no you do not need to covert to SER for Siril to work, it will take your FITS files, you simply still run it past the convert stage so it can add it to the SEQ file it creates.  You can also debay at that time. or at pre processing.
Rick Veregin avatar
Rick Veregin avatar
If there are good stars there--not large out of focus or oval stars that won't register-- your stars may be too faint to register in DSS with short exposures, so there are a couple of things you can try.

Go to Register > Advanced and make sure 2% is selected. If the image is not too noisy you can uncheck the box Reduce noise with median filter.

Finally you can go to Options > Settings > Raw/FITS DDP settings . Choose the RAW or FITS tab, depending on which you are using, and increase Brightness from the default of 1, you could increase brightness to 2 or 3 to brighten dim stars. Note, only do this for the register step. Once all your stars are registered, switch it back to 1, and then stack, so your stacked image doesn't have the brightness stretch in it.

Rick
Helpful
Arnie avatar
Arnie avatar
If all fails and you you are using Windows, there is an older program that allows one to manually pick stars for registration. I've never had AIP4Win fail to register images for me.

Arnie
Jeffbax Velocicaptor avatar
Jeffbax Velocicaptor avatar
Hi, Siril is the must for this. You Can select 3 stars for registration. Very efficient.

And this software has many more avantages…

JF
Aaron Sprague avatar
Aaron Sprague avatar
i personally use "super pixel mode" in the register settings and it fixed my issue. Siril is also great for stacking once you learn to use it
Philippe Barraud avatar
Philippe Barraud avatar
I have good results with ASI Deepstack. Very accurate and simple to use. You can add your calibration frames, of course.
MaximDL does a good job too.
Tony Gondola avatar
Tony Gondola avatar
Using Siril, you can specify how many and which stars to use for registration. even down to just one. That will work if you don't have any rotation. Not sure that many folks are still using DSS. Siril is free and much more capable, certainly worth learning and unlike PixInsight, it's free!
Concise