Workflow problem

I recently tried the manual pre-processing as described here:

But as i normally work with shorter exposures i have a problem with the background extraction during this process. When i have images of fainter objects i cannot really see the nebulosity in a single image to set the control points for the background extraction.

Does anyone have a suggestion about this problem? Can i do stacking with some of the images without background extraction and use the result for defining the anchor points for background extraction for the “original” sequence with all images?

And a question: If i use dithering the images are of course shifted. That means that samples i set near an object maybe land directly on an object in a dithered image. Maybe it would be better to first register the images before doing background extraction?

  1. Convert
  2. Preprocessing
  3. Register
  4. Background extraction
  5. Stacking

This would ensure that the samples for background extraction are on the same spots in every exposure.

Ciao, Udo

For short exposure I would suggest to not remove background. You will have too much noise so this is not ideal situation.

About the workflow, I recommend to not do it after Registration because you will have black borders.
The best is to do it before. About the position of samples? You don’t care especially with first order.

Black borders can be avoided by just cropping the sequence after registration.

Noise is maybe a problem with shorter exposures and background extraction. Too bad that i have very varying gradients during the night and because of bortle 5/6 i have no benefit of longer exposures. For me some first tests have worked quite well using the described workflow with my 30s exposures (200PDS f/5, IMX533C sensor, HCG Gain 177, Offset 100).

BTW: Wouldn’t it be a nice feature to build in a checkbox for “autocrop” during registration to automatically remove the borders?

And another point: It looks like most of the website, documentation and tutorials only is available in EN and FR. No German - althought Siril has german translations. Maybe i can help and translate at least some of the tutorials and/or the website?

Ciao, Udo

No because frames wouldn’t have the same size.

Handling several translation for website and tutorial would be too difficult.
However we work on a new documentation. This one will have many translation you could help.

OK. No PNs here in the forum? You can contact me on if i can help with the translations.

Ciao, Udo