Few days ago I've spent a night on the summit of mount Rocciamelone (3,538 m - 11,608 ft), so I could manage some night shots :-)
Conditions were almost ideal, Moonrise was scheduled for 2:57 am, and, after sunset, the starry sky remained dark for a long time.
There is always light pollution coming from the valley, which is more than three thousand meters below, but honestly I think it has not affected the view of the cosmos (photographically speaking, of course, with naked eye you can barely see these night lights).

Here you can see the massive body of the Milky Way "crashing" on the Cottian Alps (it's easy to distinguish the famous pyramidal shilouette of Monte Viso).

EDIT

I am answering here, in the caption, to your kind questions :-)

Technical data are important, but it is as well basilar to find a place where the sky is truly pitch black.
Our cameras are capable of capturing light pollution of cities many many miles away... light that our eyes can not perceive...
In fact, it's well known that through long exposures at high ISO, cameras can see things far beyond the human eye, and that's really what interested me most. I was eager to capture the cosmic clouds surrounding the Milky Way, clouds that are not visible to the naked eye with the same intensity and clarity that instead a good electronic instrumentation can offer.
This also explains why many night shots are "very clear", although I always try to overcome this aspect, because I like to keep intact the magical and silent essence of the night.
Night is the realm of mystery.
And we, photographers, must be very careful to honor this mystic aspect.

I must point out too, that finding the right spot requires a very long search! Many attempts, many failures, long walks, hiking, climbing, you need to love adventure...
I am constantly searching for best locations on the darkness of the mountains... however, please, consider that also a proper amount of light pollution can lead to very artistic results! but, it is certain, the Milky Way will be less present in the sky!
So, everything depends on the final result that we want to achieve :-)

So, here we are, I've used my Canon 5D Mark II with the 17-40 F/4 L lens.
Light and form are the essence of photography, therefore, considering that night photography means to work in very critical low light conditions (so critical that often I have to focus manually on the brightest star, because it is the only true source of light still present around me), it's very important to use bright lenses.
So, for instance, the Canon 16-35 F/2.8 L (or something equivalent from other manufacturers) would have been even better, but unfortunately I can't afford it right now.

As usual in night/astro photographic technique, this photo is obtained by combining two exposures: a very long one at low ISO for the landscape, in order to preserve details and best high definition print quality, plus a second one around thirty seconds at high ISO for the cosmos. Why? Because Earth is moving, stars are moving, fater than we can imagine, and any longer exposure would have resulted in beginning star trails.
You can still get tracks even at shorter times, it's all depending on the focal length of your lens. As wider as you go, as longer you can expose.
Basically, with my 17mm, on full frame, I've experienced that I can expose a few seconds over half a minute without getting obvious signs of stars movement, which is fine! :-)


Data of this photo are:

f/4 26s ISO 6400 @17mm full frame (for the night sky, which is in this case the 80% of the image)
f/4 65s ISO 1600 @17mm full frame (for the Alps, 20% of the image)

(Obviously it's all manual focusing, tripod, mirror lock up, remote shutter release).

You might still be wondering "ok, with the sky we have to be fast because everything is moving, rotating, etc... but why do not use even lower ISO for the foreground?"
Well, the aswer is simple: wind !!! :-) yes, at high altitudes, as in this case (3,538 m - 11,608 ft), it's almost always very windy, in waves (in the most fortunate of cases), so you have to be still pretty fast in exposing!
A long exposure can be spoiled with great ease by strong gusts of wind, no matter which tripod we are using :-)

Have I clearly answered to you questions? I hope so, also I hope to have been useful in some way :-)
all the best to you all
Roberto