Higher gain is not a problem since you are stacking lots of frames and thus increasing your signal to noise ratio.
Try your gain around the 40-50% region when imaging at 1/25th sec exposure and 10fps.
That's just a rough guide. Just watch your K3 meter and adjust the gain to get your meter in that 200+ zone.
Leave the brightness in the middle and everything else at default, and use about 15-20% gamma. Only introduce gamma after you've got your focus right.
Hope this helps
