I usually use a tripod now so that's cool so I should do that. Someone else recommended the similar thing actually (but to change layer style instead) but I completely forgot to try that. I tend to use on 2sec timer and most shots with tripod locked so doesn't shake or move (as experimenting taking stacked image for hdr) and subject often nothing moving that fast (well for a few min to make a difference). I guess the result isn't as good as single long exposure but will be better than it is. Thanks.