I have bought a "new" FM2(N i think) and I'm wondering if there is any way to tell which focusing screen is in this camera? I want to determine what I have got, and whether or not there is a different screen to that is better to make manual focusing easier. I have never had a camera with interchangeable screens before so you can safely assume that I know nothing about this.

I want the best screen because I have a 50mm f/1.2 AIS lens and I want to be able to shoot it wide open as accurately as possible.