Thank you Kevin and Rex.
Cris, yes the background is a bit light. I did so because the galaxy is very very faint. Better background needs more signal from galaxy. To bring up the galaxy I needed to lose the quality of background and with the noise.
Normally I use subs of 4 minutes because of light pollution. But with this galaxy I needed work with 5 minutes subs. Total time of 80 minutes, perhaps it needs twice more time.