Stacking Different Exposures in SIRIL

[Somerled7]

I've been taking a look at SIRIL for stacking and initial processing, but run into a problem of stacking images with different exposure times. In DSS there are different tabs to group Light files along with their corresponding Dark Files, but I don't see anything similar in SIRIL. Is it a case of throwing everything in and the program sorts it out, or is it necessary to stack each set of images separately then combine the final stacked results? Can anyone advise?

[lock042]

This is because we never should try to stack different exposures in sametime... DSS is doing that, that's right. But for me this is a big mistake.

You need to stack consistent frames.

So, stack each exposures to produce different images. And then, merge the image withing GIMP. I guess you shot M42.

Edited March 6, 2021 by lock042

[The Lazy Astronomer]

The groups in DSS should really only be used if you shot over multiple nights and have different calibration frames for each night. You shouldn't be stacking subs of different exposure length. 

[ollypenrice]

I agree with the others. The need for different exposure times is grossly exaggerated and in over ten years of deep sky imaging, as a provider, I have used different exposure times on fewer than half a dozen images. The obvious one is M42. After that, well.... I really can't remember!

Olly

[lock042]

@Somerled7: https://siril.org/faq/#how-can-i-combine-different-exposures-on-the-same-object

[Somerled7]

Haven't been back to check replies because I've been busy elsewhere.  I ended up with different exposure length subs by accident rater than design. Looking for something to image under a bright moon (mainly for practice!) I opted for the Double Cluster in Perseus. As the moon was bright, I took shorter subs than I normally use to avoid over-exposing the sky. I had some older images with longer subs of the same subject, so was looking to see if I could combine them.  In the end, I stacked each set separately, then overlaid and combined in Photoshop - interesting to see the noise reducing as the two stacked images were combined.