Last night I was in a orange bortle class area,which is where I live,trying my Russian 20x60 binoculars but tonight,on a brief break,in the dark blue bortle class area.what a difference! The orange has a naked eye limiting magnitude of 4.5 the dark blue 5.75.I'm only equiped with my little Opticron 8x25 monocular but things like m36,37,38 just jump out in the blue area. in the orange you have to try and see them,m38 being the most difficult. I'm pretty sure I got m1 and m82 too?m31 and m44 easy naked eye objects in the blue area.yet sadly the dark blue, and black areas,are shrinking across our planet.