Newbie: stack together images with different lens aperture?

[gerlos]

Hello everyone!
I'm quite new with PixInsight, so be patient if my question seems stupid...

Last summer I took ~20 light frames with my canon 550D and an old nikon lens. First night I did the mistake of leaving the lens full open at f/1.8, and got really a lot of signal, but very distorted stars and low contrast. During the second night, I closed it down to f/5.6, and got a lot sharper images (look at attached image).
I've got a full set of bias, dark and flat frames from both nights.

My question: can I combine these two sets of light frames? In theory, is it something that should be avoided, or is it ok to do?

More precisely: can I preprocess them together in the BatchPreProcessing script?
Will PixInsight use the right flats for each set, or I need to calibrate frames individually, and them stack together in a second step?

Many thanks in advance,
gerlos

[gerlos]

Did my experiment, stuffing in BachPreProcess script all my 39 light frames (total: 4.5hours), taken with different aperture (f/1.8 and f/5.6) and exposure times (300s and 600s), together with all my flat, dark and bias frames.

Looking at the (almost) unprocessed results (attached), I'm surprised and really happy. Really, didn't expect such good result, comparing it with this previous result: http://www.astrobin.com/55802/

It seems to me that PixInsight stacking and rejection algorithms corrected almost every optical defect from my original frames, great!

I guess this is because every set was slightly displaced relative to the other, and some of them were even inverted, since they were taken on the opposite side of the meridian, so it results somehow in an unintentional "dithering". What do you think?

An higher res version, with more details is here: http://www.astrobin.com/58291/

Now I'm looking at some tutorials to learn how to post process this image. Any suggestion is welcome.

regards
gerlos

[pfile]

looks pretty good, the background just needs neutralization; slight green cast. maybe a bit of star reduction to reveal the nebulae a bit more.

rob