With good dark skies, what should I be able to find?

[Manok101]

I've got an Orion xt4.5 dob, and was wondering what the faintest objects I should be able to see? (I haven't had a chance to take it out to a dark place yet).

[acey]

It gains about 6 magnitudes over what you see with the naked eye, so if you can see stars down to mag 4 with unaided eye then you'll see stars down to 10 with the scope; if you're at a dark site (mag 6 naked eye) you'll see stars down to mag 12 with the scope. Easily enough for all the major planets and also some minor ones (though not Pluto).

Judging visibility of deep-sky objects is harder because the key thing there is surface brightness rather than magnitude. But at a site that's dark enough for the Milky Way to be visible you should be able to see all the Messiers and a lot of NGCs.