I have wanted to have an efficient way to do long exposure via multiple stacked short exposures, so it is great to hear that Siril does this!
I have a question about this technique. Instead of taking a long - say 10 minute exposure, I could take N pictures of M seconds each.
Do you have any rule of thumb on how many photos it takes to achieve a smooth long exposure look? Also, does it matter if the individual shots are also long-ish to get blur?
Here is an example. Instead of the hypothetical 10 min exposure, I could take 600 shots each at 1 sec each. That would exactly equal the singe 10 min exposure, so this ought to work.
Except for the fact that you must process all of the images there are several convenience aspects of doing the multiple shots. You don’t need a super dark 10 stop ND filter, or an intervalometer. You can use the outlier rejection algorithm in Siril to throw away true anomalies.
But I wonder whether you can get by with fewer shots? Or shorter exposures? Or both?
600 shots at 1/100 sec each would only be 6 seconds of total exposure, but if they were taken over 10 minutes they might average to something that is visually similar. Even if each shot is sharp, having 600 of them ought to average out to being smooth for most subjects.
An average of 600 images which ought to make differences between individual shots hard to detect.
What about 100 shots, each at 1 sec exposure, but taken over a period of 10 min?
Obviously it is not possible to answer this in a very detailed way for all subjects. Static items (rocks, buildings etc) should be the same in all approaches Very fast moving things (cars on freeway, fast moving water, flying birds) would presumably be quite different than slow moving things (slow water current, tide coming in).
But I am still curious as to what you have found.